<?xml version="1.0" encoding="UTF-8"?>

<!--XBRL Document Created with the Workiva Platform-->
<!--Copyright 2026 Workiva-->
<!--r:01a01567-f9b0-7912-91a1-e71c50b1f080,g:c84951dc-aaa3-441a-b809-abf656910511-->
<link:linkbase xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd">
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/all" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member"/>
  <link:roleRef roleURI="http://www.wdc.com/role/CONDENSEDCONSOLIDATEDSTATEMENTSOFCONVERTIBLEPREFERREDSTOCKANDSHAREHOLDERSEQUITY" xlink:type="simple" xlink:href="wdc-20261002.xsd#CONDENSEDCONSOLIDATEDSTATEMENTSOFCONVERTIBLEPREFERREDSTOCKANDSHAREHOLDERSEQUITY"/>
  <link:definitionLink xlink:role="http://www.wdc.com/role/CONDENSEDCONSOLIDATEDSTATEMENTSOFCONVERTIBLEPREFERREDSTOCKANDSHAREHOLDERSEQUITY" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_01a01567-fb88-7212-b262-71d9aa5ac419" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_01a01567-fb88-7851-9d35-63fd0a328bea" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_01a01567-fb88-7212-b262-71d9aa5ac419" xlink:to="loc_us-gaap_StatementTable_01a01567-fb88-7851-9d35-63fd0a328bea" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_01a01567-fb88-79b0-83f8-4a64eacb1471" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_01a01567-fb88-7851-9d35-63fd0a328bea" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_01a01567-fb88-79b0-83f8-4a64eacb1471" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_01a01567-fb88-79b0-83f8-4a64eacb1471_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_01a01567-fb88-79b0-83f8-4a64eacb1471" xlink:to="loc_us-gaap_EquityComponentDomain_01a01567-fb88-79b0-83f8-4a64eacb1471_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_01a01567-fb88-7b48-910a-01bad23ccb03" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_01a01567-fb88-79b0-83f8-4a64eacb1471" xlink:to="loc_us-gaap_EquityComponentDomain_01a01567-fb88-7b48-910a-01bad23ccb03" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_01a01567-fb88-7b98-b655-317aa49b876b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_01a01567-fb88-7b48-910a-01bad23ccb03" xlink:to="loc_us-gaap_CommonStockMember_01a01567-fb88-7b98-b655-317aa49b876b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockCommonMember_01a01567-fb88-703b-bf88-23b905653d73" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TreasuryStockCommonMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_01a01567-fb88-7b48-910a-01bad23ccb03" xlink:to="loc_us-gaap_TreasuryStockCommonMember_01a01567-fb88-703b-bf88-23b905653d73" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapitalMember_01a01567-fb88-7b39-b0e5-5c7aafec8e70" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AdditionalPaidInCapitalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_01a01567-fb88-7b48-910a-01bad23ccb03" xlink:to="loc_us-gaap_AdditionalPaidInCapitalMember_01a01567-fb88-7b39-b0e5-5c7aafec8e70" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_01a01567-fb88-7fe3-990f-1dfc246e0681" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_01a01567-fb88-7b48-910a-01bad23ccb03" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_01a01567-fb88-7fe3-990f-1dfc246e0681" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsMember_01a01567-fb88-7c65-8f50-db6c5274f405" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RetainedEarningsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_01a01567-fb88-7b48-910a-01bad23ccb03" xlink:to="loc_us-gaap_RetainedEarningsMember_01a01567-fb88-7c65-8f50-db6c5274f405" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInTemporaryEquityRollForward_01a01567-fb88-7e4e-a6ec-310e34f77647" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncreaseDecreaseInTemporaryEquityRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_01a01567-fb88-7212-b262-71d9aa5ac419" xlink:to="loc_us-gaap_IncreaseDecreaseInTemporaryEquityRollForward_01a01567-fb88-7e4e-a6ec-310e34f77647" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TemporaryEquitySharesOutstanding_01a01567-fb88-7551-bd7b-bdb07337d6b5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TemporaryEquitySharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInTemporaryEquityRollForward_01a01567-fb88-7e4e-a6ec-310e34f77647" xlink:to="loc_us-gaap_TemporaryEquitySharesOutstanding_01a01567-fb88-7551-bd7b-bdb07337d6b5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TemporaryEquityCarryingAmountIncludingPortionAttributableToNoncontrollingInterests_01a01567-fb88-78ff-bc5c-0eb242f16aeb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TemporaryEquityCarryingAmountIncludingPortionAttributableToNoncontrollingInterests"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInTemporaryEquityRollForward_01a01567-fb88-7e4e-a6ec-310e34f77647" xlink:to="loc_us-gaap_TemporaryEquityCarryingAmountIncludingPortionAttributableToNoncontrollingInterests_01a01567-fb88-78ff-bc5c-0eb242f16aeb" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TemporaryEquitySharesOutstanding_01a01567-fb88-7202-a9cd-eff503e3b987" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TemporaryEquitySharesOutstanding"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TemporaryEquityCarryingAmountIncludingPortionAttributableToNoncontrollingInterests_01a01567-fb88-75a2-b9d1-4925253abc5f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TemporaryEquityCarryingAmountIncludingPortionAttributableToNoncontrollingInterests"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_01a01567-fb88-7a64-b4eb-c97013c14e01" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncreaseDecreaseInStockholdersEquityRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_01a01567-fb88-7212-b262-71d9aa5ac419" xlink:to="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_01a01567-fb88-7a64-b4eb-c97013c14e01" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesIssued_01a01567-fb88-766a-827f-c605e060f422" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockSharesIssued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_01a01567-fb88-7a64-b4eb-c97013c14e01" xlink:to="loc_us-gaap_CommonStockSharesIssued_01a01567-fb88-766a-827f-c605e060f422" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_01a01567-fb88-778d-91de-f0be64c971ca" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockholdersEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_01a01567-fb88-7a64-b4eb-c97013c14e01" xlink:to="loc_us-gaap_StockholdersEquity_01a01567-fb88-778d-91de-f0be64c971ca" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockCommonShares_01a01567-fb88-7be2-9ab7-d0e10bbbf4ab" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TreasuryStockCommonShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_01a01567-fb88-7a64-b4eb-c97013c14e01" xlink:to="loc_us-gaap_TreasuryStockCommonShares_01a01567-fb88-7be2-9ab7-d0e10bbbf4ab" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_01a01567-fb88-7218-b36b-d39f6b52ab8a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_01a01567-fb88-7a64-b4eb-c97013c14e01" xlink:to="loc_us-gaap_NetIncomeLoss_01a01567-fb88-7218-b36b-d39f6b52ab8a" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans_01a0a87f-7534-7bd3-8331-cf23e1c1b644" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_01a01567-fb88-7a64-b4eb-c97013c14e01" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans_01a0a87f-7534-7bd3-8331-cf23e1c1b644" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardNetOfForfeitures_01a01567-fc28-76f0-ae79-5e41c9c86955" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardNetOfForfeitures"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_01a01567-fb88-7a64-b4eb-c97013c14e01" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardNetOfForfeitures_01a01567-fc28-76f0-ae79-5e41c9c86955" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_01a01567-fc28-7d50-8198-b76d5066a59c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_01a01567-fb88-7a64-b4eb-c97013c14e01" xlink:to="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_01a01567-fc28-7d50-8198-b76d5066a59c" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchasedDuringPeriodShares_01a0a881-bbb2-7d23-a250-1ea3008cab05" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockRepurchasedDuringPeriodShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_01a01567-fb88-7a64-b4eb-c97013c14e01" xlink:to="loc_us-gaap_StockRepurchasedDuringPeriodShares_01a0a881-bbb2-7d23-a250-1ea3008cab05" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchasedDuringPeriodValue_01a01567-fc28-7144-b6c1-4dfa3d7cec65" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockRepurchasedDuringPeriodValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_01a01567-fb88-7a64-b4eb-c97013c14e01" xlink:to="loc_us-gaap_StockRepurchasedDuringPeriodValue_01a01567-fc28-7144-b6c1-4dfa3d7cec65" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_StockIssuedDuringPeriodSharesConvertibleNotesTransactions_01a12dcf-655b-77c7-b31d-7a9fb5e456cf" xlink:href="wdc-20261002.xsd#wdc_StockIssuedDuringPeriodSharesConvertibleNotesTransactions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_01a01567-fb88-7a64-b4eb-c97013c14e01" xlink:to="loc_wdc_StockIssuedDuringPeriodSharesConvertibleNotesTransactions_01a12dcf-655b-77c7-b31d-7a9fb5e456cf" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_StockIssuedDuringPeriodValueConvertibleNotesTransaction_01a12dd0-592e-7ec6-8ca3-6f3635cd01cc" xlink:href="wdc-20261002.xsd#wdc_StockIssuedDuringPeriodValueConvertibleNotesTransaction"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_01a01567-fb88-7a64-b4eb-c97013c14e01" xlink:to="loc_wdc_StockIssuedDuringPeriodValueConvertibleNotesTransaction_01a12dd0-592e-7ec6-8ca3-6f3635cd01cc" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendsPreferredStockCash_01a01567-fc28-7193-b0e4-d36e3f4de3db" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DividendsPreferredStockCash"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_01a01567-fb88-7a64-b4eb-c97013c14e01" xlink:to="loc_us-gaap_DividendsPreferredStockCash_01a01567-fc28-7193-b0e4-d36e3f4de3db" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendsCommonStock_01a01567-fc28-7062-8750-18f235e5ca1b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DividendsCommonStock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_01a01567-fb88-7a64-b4eb-c97013c14e01" xlink:to="loc_us-gaap_DividendsCommonStock_01a01567-fc28-7062-8750-18f235e5ca1b" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax_01a12dd1-7c79-7419-9f6b-58638ef8e02c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_01a01567-fb88-7a64-b4eb-c97013c14e01" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax_01a12dd1-7c79-7419-9f6b-58638ef8e02c" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAfterTax_01a01567-fc28-7d87-b040-db0b394ba1aa" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAfterTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_01a01567-fb88-7a64-b4eb-c97013c14e01" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAfterTax_01a01567-fc28-7d87-b040-db0b394ba1aa" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_AdjustmentsToAdditionalPaidInCapital_01a12dd2-6991-7f5e-8f85-fbe8fe8b04d7" xlink:href="wdc-20261002.xsd#wdc_AdjustmentsToAdditionalPaidInCapital"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_01a01567-fb88-7a64-b4eb-c97013c14e01" xlink:to="loc_wdc_AdjustmentsToAdditionalPaidInCapital_01a12dd2-6991-7f5e-8f85-fbe8fe8b04d7" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesIssued_01a01567-fc28-7b13-851f-e5028834d96a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockSharesIssued"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_01a01567-fc28-7518-9423-49a02f07f6ed" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockholdersEquity"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockCommonShares_01a01567-fc28-7eab-b13b-943b29b8e7f9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TreasuryStockCommonShares"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.wdc.com/role/DisaggregatedRevenueGeographicInformationConcentrationsofRiskandSegmentReportingScheduleofDisaggregationofRevenueDetails" xlink:type="simple" xlink:href="wdc-20261002.xsd#DisaggregatedRevenueGeographicInformationConcentrationsofRiskandSegmentReportingScheduleofDisaggregationofRevenueDetails"/>
  <link:definitionLink xlink:role="http://www.wdc.com/role/DisaggregatedRevenueGeographicInformationConcentrationsofRiskandSegmentReportingScheduleofDisaggregationofRevenueDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueLineItems_01a01567-fc29-7f79-b507-ae8c68d61743" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DisaggregationOfRevenueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueTable_01a01567-fc29-79de-aa41-550b4ee361a8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DisaggregationOfRevenueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_01a01567-fc29-7f79-b507-ae8c68d61743" xlink:to="loc_us-gaap_DisaggregationOfRevenueTable_01a01567-fc29-79de-aa41-550b4ee361a8" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_01a01567-fc29-7757-a904-1ab1ab0bac3b" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_01a01567-fc29-79de-aa41-550b4ee361a8" xlink:to="loc_srt_ProductOrServiceAxis_01a01567-fc29-7757-a904-1ab1ab0bac3b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_01a01567-fc29-7757-a904-1ab1ab0bac3b_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_01a01567-fc29-7757-a904-1ab1ab0bac3b" xlink:to="loc_srt_ProductsAndServicesDomain_01a01567-fc29-7757-a904-1ab1ab0bac3b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_01a01567-fc29-70b4-a08e-832a04bfd509" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_01a01567-fc29-7757-a904-1ab1ab0bac3b" xlink:to="loc_srt_ProductsAndServicesDomain_01a01567-fc29-70b4-a08e-832a04bfd509" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_CloudMember_01a01567-fc29-7dcd-b7b5-90d671eb5827" xlink:href="wdc-20261002.xsd#wdc_CloudMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_01a01567-fc29-70b4-a08e-832a04bfd509" xlink:to="loc_wdc_CloudMember_01a01567-fc29-7dcd-b7b5-90d671eb5827" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_ClientDevicesMember_01a01567-fc29-7186-8199-0ea356818a0f" xlink:href="wdc-20261002.xsd#wdc_ClientDevicesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_01a01567-fc29-70b4-a08e-832a04bfd509" xlink:to="loc_wdc_ClientDevicesMember_01a01567-fc29-7186-8199-0ea356818a0f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_ConsumerMember_01a01567-fc29-7510-8be1-deb2638efd2a" xlink:href="wdc-20261002.xsd#wdc_ConsumerMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_01a01567-fc29-70b4-a08e-832a04bfd509" xlink:to="loc_wdc_ConsumerMember_01a01567-fc29-7510-8be1-deb2638efd2a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementGeographicalAxis_01a01567-fc29-7b58-a6c8-3aaac2b3513c" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_StatementGeographicalAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_01a01567-fc29-79de-aa41-550b4ee361a8" xlink:to="loc_srt_StatementGeographicalAxis_01a01567-fc29-7b58-a6c8-3aaac2b3513c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_01a01567-fc29-7b58-a6c8-3aaac2b3513c_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementGeographicalAxis_01a01567-fc29-7b58-a6c8-3aaac2b3513c" xlink:to="loc_srt_SegmentGeographicalDomain_01a01567-fc29-7b58-a6c8-3aaac2b3513c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_01a01567-fc29-76fa-ac27-194660f057af" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementGeographicalAxis_01a01567-fc29-7b58-a6c8-3aaac2b3513c" xlink:to="loc_srt_SegmentGeographicalDomain_01a01567-fc29-76fa-ac27-194660f057af" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_AmericasMember_01a01567-fc29-7e38-bb7d-ba03ccb80abb" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_AmericasMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_01a01567-fc29-76fa-ac27-194660f057af" xlink:to="loc_srt_AmericasMember_01a01567-fc29-7e38-bb7d-ba03ccb80abb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_AsiaMember_01a01567-fc29-7ec2-b9d4-d931d7c5202b" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_AsiaMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_01a01567-fc29-76fa-ac27-194660f057af" xlink:to="loc_srt_AsiaMember_01a01567-fc29-7ec2-b9d4-d931d7c5202b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_EuropeMiddleEastAndAfricaMember_01a01567-fc29-7429-a77d-83429960f502" xlink:href="wdc-20261002.xsd#wdc_EuropeMiddleEastAndAfricaMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_01a01567-fc29-76fa-ac27-194660f057af" xlink:to="loc_wdc_EuropeMiddleEastAndAfricaMember_01a01567-fc29-7429-a77d-83429960f502" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_01a01567-fc29-7c13-bbcd-5516bfa41f72" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_01a01567-fc29-7f79-b507-ae8c68d61743" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_01a01567-fc29-7c13-bbcd-5516bfa41f72" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.wdc.com/role/DisaggregatedRevenueGeographicInformationConcentrationsofRiskandSegmentReportingAdditionalInformationDetails" xlink:type="simple" xlink:href="wdc-20261002.xsd#DisaggregatedRevenueGeographicInformationConcentrationsofRiskandSegmentReportingAdditionalInformationDetails"/>
  <link:definitionLink xlink:role="http://www.wdc.com/role/DisaggregatedRevenueGeographicInformationConcentrationsofRiskandSegmentReportingAdditionalInformationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskLineItems_01a01567-fc29-7f51-8ac0-0c1a626b3689" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTable_01a01567-fc29-721c-b43f-61db89597e9d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_01a01567-fc29-7f51-8ac0-0c1a626b3689" xlink:to="loc_us-gaap_ConcentrationRiskTable_01a01567-fc29-721c-b43f-61db89597e9d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_01a01567-fc29-7086-9da3-a57bca5824ba" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskByBenchmarkAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConcentrationRiskTable_01a01567-fc29-721c-b43f-61db89597e9d" xlink:to="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_01a01567-fc29-7086-9da3-a57bca5824ba" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_01a01567-fc29-7086-9da3-a57bca5824ba_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskBenchmarkDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_01a01567-fc29-7086-9da3-a57bca5824ba" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_01a01567-fc29-7086-9da3-a57bca5824ba_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_01a01567-fc29-74d3-9a84-7e62bc3abdae" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskBenchmarkDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_01a01567-fc29-7086-9da3-a57bca5824ba" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_01a01567-fc29-74d3-9a84-7e62bc3abdae" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerMember_01a01567-fc29-713e-9b8c-062cafcd3bd0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RevenueFromContractWithCustomerMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskBenchmarkDomain_01a01567-fc29-74d3-9a84-7e62bc3abdae" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerMember_01a01567-fc29-713e-9b8c-062cafcd3bd0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsReceivableMember_01a01567-fc29-7423-962c-81f0e234184b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccountsReceivableMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskBenchmarkDomain_01a01567-fc29-74d3-9a84-7e62bc3abdae" xlink:to="loc_us-gaap_AccountsReceivableMember_01a01567-fc29-7423-962c-81f0e234184b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskByTypeAxis_01a01567-fc29-7687-b700-021dfc495db8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConcentrationRiskTable_01a01567-fc29-721c-b43f-61db89597e9d" xlink:to="loc_us-gaap_ConcentrationRiskByTypeAxis_01a01567-fc29-7687-b700-021dfc495db8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_01a01567-fc29-7687-b700-021dfc495db8_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_01a01567-fc29-7687-b700-021dfc495db8" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_01a01567-fc29-7687-b700-021dfc495db8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_01a01567-fc29-7ef0-a3b6-afbc705018c2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_01a01567-fc29-7687-b700-021dfc495db8" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_01a01567-fc29-7ef0-a3b6-afbc705018c2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerConcentrationRiskMember_01a01567-fc29-7cab-83e6-a98b1bf113b6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CustomerConcentrationRiskMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskTypeDomain_01a01567-fc29-7ef0-a3b6-afbc705018c2" xlink:to="loc_us-gaap_CustomerConcentrationRiskMember_01a01567-fc29-7cab-83e6-a98b1bf113b6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MajorCustomersAxis_01a01567-fc29-7e3f-ab87-15b2e6513245" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MajorCustomersAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConcentrationRiskTable_01a01567-fc29-721c-b43f-61db89597e9d" xlink:to="loc_srt_MajorCustomersAxis_01a01567-fc29-7e3f-ab87-15b2e6513245" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_01a01567-fc29-7e3f-ab87-15b2e6513245_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_NameOfMajorCustomerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_MajorCustomersAxis_01a01567-fc29-7e3f-ab87-15b2e6513245" xlink:to="loc_srt_NameOfMajorCustomerDomain_01a01567-fc29-7e3f-ab87-15b2e6513245_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_01a01567-fc29-79c7-b34f-921b84a1f746" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_NameOfMajorCustomerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_MajorCustomersAxis_01a01567-fc29-7e3f-ab87-15b2e6513245" xlink:to="loc_srt_NameOfMajorCustomerDomain_01a01567-fc29-79c7-b34f-921b84a1f746" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_TopTenCustomersMember_01a01567-fc29-7cd9-8457-1aef2b595757" xlink:href="wdc-20261002.xsd#wdc_TopTenCustomersMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_01a01567-fc29-79c7-b34f-921b84a1f746" xlink:to="loc_wdc_TopTenCustomersMember_01a01567-fc29-7cd9-8457-1aef2b595757" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_CustomerOneMember_01a01567-fc29-7fb4-b5a5-5b3ac8335cdf" xlink:href="wdc-20261002.xsd#wdc_CustomerOneMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_01a01567-fc29-79c7-b34f-921b84a1f746" xlink:to="loc_wdc_CustomerOneMember_01a01567-fc29-7fb4-b5a5-5b3ac8335cdf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_CustomerTwoMember_01a01567-fc29-7198-b89d-ad562b8da5c3" xlink:href="wdc-20261002.xsd#wdc_CustomerTwoMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_01a01567-fc29-79c7-b34f-921b84a1f746" xlink:to="loc_wdc_CustomerTwoMember_01a01567-fc29-7198-b89d-ad562b8da5c3" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_CustomerThreeMember_01a01567-fc29-7a80-8c86-63f45713dcba" xlink:href="wdc-20261002.xsd#wdc_CustomerThreeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_01a01567-fc29-79c7-b34f-921b84a1f746" xlink:to="loc_wdc_CustomerThreeMember_01a01567-fc29-7a80-8c86-63f45713dcba" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_CustomerFourMember_01a142e5-a169-77d4-b38c-18ca679d80b5" xlink:href="wdc-20261002.xsd#wdc_CustomerFourMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_01a01567-fc29-79c7-b34f-921b84a1f746" xlink:to="loc_wdc_CustomerFourMember_01a142e5-a169-77d4-b38c-18ca679d80b5" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskPercentage1_01a01567-fc29-7947-a973-4c08c9ac9483" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskPercentage1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_01a01567-fc29-7f51-8ac0-0c1a626b3689" xlink:to="loc_us-gaap_ConcentrationRiskPercentage1_01a01567-fc29-7947-a973-4c08c9ac9483" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsReceivableNetCurrent_01a01567-fc29-74aa-a6d6-da4c4bd20fbe" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccountsReceivableNetCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_01a01567-fc29-7f51-8ac0-0c1a626b3689" xlink:to="loc_us-gaap_AccountsReceivableNetCurrent_01a01567-fc29-74aa-a6d6-da4c4bd20fbe" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NumberOfReportableSegments_01a01567-fc29-7d75-a329-0d0deaa22c12" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NumberOfReportableSegments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_01a01567-fc29-7f51-8ac0-0c1a626b3689" xlink:to="loc_us-gaap_NumberOfReportableSegments_01a01567-fc29-7d75-a329-0d0deaa22c12" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.wdc.com/role/DisaggregatedRevenueGeographicInformationConcentrationsofRiskandSegmentReportingScheduleofSegmentReportingDetails" xlink:type="simple" xlink:href="wdc-20261002.xsd#DisaggregatedRevenueGeographicInformationConcentrationsofRiskandSegmentReportingScheduleofSegmentReportingDetails"/>
  <link:definitionLink xlink:role="http://www.wdc.com/role/DisaggregatedRevenueGeographicInformationConcentrationsofRiskandSegmentReportingScheduleofSegmentReportingDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_01a01567-fc29-708b-89b5-cacb66f534be" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentReportingInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_01a01567-fc29-79a8-8b16-ca6f950a3980" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_01a01567-fc29-708b-89b5-cacb66f534be" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_01a01567-fc29-79a8-8b16-ca6f950a3980" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_01a01567-fc29-773d-be18-3b0091d5eeae" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_01a01567-fc29-79a8-8b16-ca6f950a3980" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_01a01567-fc29-773d-be18-3b0091d5eeae" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_01a01567-fc29-773d-be18-3b0091d5eeae_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_01a01567-fc29-773d-be18-3b0091d5eeae" xlink:to="loc_us-gaap_SegmentDomain_01a01567-fc29-773d-be18-3b0091d5eeae_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_01a01567-fc29-73e1-bb9f-15c68d657150" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_01a01567-fc29-773d-be18-3b0091d5eeae" xlink:to="loc_us-gaap_SegmentDomain_01a01567-fc29-73e1-bb9f-15c68d657150" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_HDDMember_01a01567-fc29-7bc4-9e48-d7b8c101fd6e" xlink:href="wdc-20261002.xsd#wdc_HDDMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_01a01567-fc29-73e1-bb9f-15c68d657150" xlink:to="loc_wdc_HDDMember_01a01567-fc29-7bc4-9e48-d7b8c101fd6e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_01a01567-fc29-75bc-8413-2cc7752aee6c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_01a01567-fc29-708b-89b5-cacb66f534be" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_01a01567-fc29-75bc-8413-2cc7752aee6c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_CostOfProductAndServiceSoldAdjusted_01a01567-fc29-7312-9e50-adc57c2d65ab" xlink:href="wdc-20261002.xsd#wdc_CostOfProductAndServiceSoldAdjusted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_01a01567-fc29-708b-89b5-cacb66f534be" xlink:to="loc_wdc_CostOfProductAndServiceSoldAdjusted_01a01567-fc29-7312-9e50-adc57c2d65ab" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_ResearchAndDevelopmentExpenseExcludingAcquiredInProcessCostAdjusted_01a01567-fc29-7c7d-965a-18f7253f6a27" xlink:href="wdc-20261002.xsd#wdc_ResearchAndDevelopmentExpenseExcludingAcquiredInProcessCostAdjusted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_01a01567-fc29-708b-89b5-cacb66f534be" xlink:to="loc_wdc_ResearchAndDevelopmentExpenseExcludingAcquiredInProcessCostAdjusted_01a01567-fc29-7c7d-965a-18f7253f6a27" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_SellingGeneralAndAdministrativeExpenseAdjusted_01a01567-fc29-7504-97c2-f593f317ef4b" xlink:href="wdc-20261002.xsd#wdc_SellingGeneralAndAdministrativeExpenseAdjusted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_01a01567-fc29-708b-89b5-cacb66f534be" xlink:to="loc_wdc_SellingGeneralAndAdministrativeExpenseAdjusted_01a01567-fc29-7504-97c2-f593f317ef4b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensation_01a01567-fc29-7fbc-b854-845ef3b975dd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_01a01567-fc29-708b-89b5-cacb66f534be" xlink:to="loc_us-gaap_ShareBasedCompensation_01a01567-fc29-7fbc-b854-845ef3b975dd" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_BusinessRealignmentCharges_01a01567-fc29-7d3e-8ef7-b1f15117098d" xlink:href="wdc-20261002.xsd#wdc_BusinessRealignmentCharges"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_01a01567-fc29-708b-89b5-cacb66f534be" xlink:to="loc_wdc_BusinessRealignmentCharges_01a01567-fc29-7d3e-8ef7-b1f15117098d" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestIncomeExpenseNonoperatingNet_01a01567-fc29-74ce-97e2-119555bee42c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestIncomeExpenseNonoperatingNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_01a01567-fc29-708b-89b5-cacb66f534be" xlink:to="loc_us-gaap_InterestIncomeExpenseNonoperatingNet_01a01567-fc29-74ce-97e2-119555bee42c" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquitySecuritiesFvNiUnrealizedGainLoss_01a01567-fc29-7c50-91b5-8b45c1149c6d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquitySecuritiesFvNiUnrealizedGainLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_01a01567-fc29-708b-89b5-cacb66f534be" xlink:to="loc_us-gaap_EquitySecuritiesFvNiUnrealizedGainLoss_01a01567-fc29-7c50-91b5-8b45c1149c6d" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherExpenses_01a01567-fc29-75b3-b5b2-56d41a00ec2d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherExpenses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_01a01567-fc29-708b-89b5-cacb66f534be" xlink:to="loc_us-gaap_OtherExpenses_01a01567-fc29-75b3-b5b2-56d41a00ec2d" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingOtherItemAmount_01a01567-fc29-79d8-8ea6-4fdda31b22d4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentReportingOtherItemAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_01a01567-fc29-708b-89b5-cacb66f534be" xlink:to="loc_us-gaap_SegmentReportingOtherItemAmount_01a01567-fc29-79d8-8ea6-4fdda31b22d4" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_01a01567-fc29-703e-8979-2534311a9a3f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeTaxExpenseBenefit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_01a01567-fc29-708b-89b5-cacb66f534be" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefit_01a01567-fc29-703e-8979-2534311a9a3f" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_01a0a894-1a49-78f8-9af9-2a6f73157b9f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_01a01567-fc29-708b-89b5-cacb66f534be" xlink:to="loc_us-gaap_NetIncomeLoss_01a0a894-1a49-78f8-9af9-2a6f73157b9f" xlink:type="arc" order="11"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.wdc.com/role/SupplementalFinancialStatementDataScheduleofPropertyPlantandEquipmentNetDetails" xlink:type="simple" xlink:href="wdc-20261002.xsd#SupplementalFinancialStatementDataScheduleofPropertyPlantandEquipmentNetDetails"/>
  <link:definitionLink xlink:role="http://www.wdc.com/role/SupplementalFinancialStatementDataScheduleofPropertyPlantandEquipmentNetDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems_01a01567-fc29-75aa-9714-482fb3e50b80" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_01a01567-fc29-728a-b638-b4ce679f21bd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_01a01567-fc29-75aa-9714-482fb3e50b80" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_01a01567-fc29-728a-b638-b4ce679f21bd" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_01a01567-fc29-73f4-9051-54052003fb35" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_01a01567-fc29-728a-b638-b4ce679f21bd" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_01a01567-fc29-73f4-9051-54052003fb35" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_01a01567-fc29-73f4-9051-54052003fb35_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_01a01567-fc29-73f4-9051-54052003fb35" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_01a01567-fc29-73f4-9051-54052003fb35_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_01a01567-fc29-7af3-991f-7880e5ce8739" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_01a01567-fc29-73f4-9051-54052003fb35" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_01a01567-fc29-7af3-991f-7880e5ce8739" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LandAndLandImprovementsMember_01a01567-fc29-795b-8c1e-00a4df5927b0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LandAndLandImprovementsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_01a01567-fc29-7af3-991f-7880e5ce8739" xlink:to="loc_us-gaap_LandAndLandImprovementsMember_01a01567-fc29-795b-8c1e-00a4df5927b0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BuildingAndBuildingImprovementsMember_01a01567-fc29-7b24-b18f-1652fd7fd438" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BuildingAndBuildingImprovementsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_01a01567-fc29-7af3-991f-7880e5ce8739" xlink:to="loc_us-gaap_BuildingAndBuildingImprovementsMember_01a01567-fc29-7b24-b18f-1652fd7fd438" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MachineryAndEquipmentMember_01a01567-fc29-7b64-ae72-e54c208133f5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MachineryAndEquipmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_01a01567-fc29-7af3-991f-7880e5ce8739" xlink:to="loc_us-gaap_MachineryAndEquipmentMember_01a01567-fc29-7b64-ae72-e54c208133f5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_ComputerEquipmentandSoftwareMember_01a01567-fc29-7f3d-ba66-a12ccda67319" xlink:href="wdc-20261002.xsd#wdc_ComputerEquipmentandSoftwareMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_01a01567-fc29-7af3-991f-7880e5ce8739" xlink:to="loc_wdc_ComputerEquipmentandSoftwareMember_01a01567-fc29-7f3d-ba66-a12ccda67319" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FurnitureAndFixturesMember_01a01567-fc29-716d-b3b2-5a911c6d33ff" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FurnitureAndFixturesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_01a01567-fc29-7af3-991f-7880e5ce8739" xlink:to="loc_us-gaap_FurnitureAndFixturesMember_01a01567-fc29-716d-b3b2-5a911c6d33ff" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConstructionInProgressMember_01a01567-fc29-7da1-9938-8e98ddba4168" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConstructionInProgressMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_01a01567-fc29-7af3-991f-7880e5ce8739" xlink:to="loc_us-gaap_ConstructionInProgressMember_01a01567-fc29-7da1-9938-8e98ddba4168" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNetAbstract_01a01567-fc29-7b31-b157-84d3e91b2a14" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentNetAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_01a01567-fc29-75aa-9714-482fb3e50b80" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentNetAbstract_01a01567-fc29-7b31-b157-84d3e91b2a14" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentGross_01a01567-fc29-776e-89fb-a37dc67a0ec9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentNetAbstract_01a01567-fc29-7b31-b157-84d3e91b2a14" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentGross_01a01567-fc29-776e-89fb-a37dc67a0ec9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_01a01567-fc29-7523-ada2-608c996a552a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentNetAbstract_01a01567-fc29-7b31-b157-84d3e91b2a14" xlink:to="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_01a01567-fc29-7523-ada2-608c996a552a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNet_01a01567-fc29-7a66-973f-94d082ae368a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentNetAbstract_01a01567-fc29-7b31-b157-84d3e91b2a14" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentNet_01a01567-fc29-7a66-973f-94d082ae368a" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.wdc.com/role/SupplementalFinancialStatementDataScheduleofAccumulatedOtherComprehensiveIncomeDetails" xlink:type="simple" xlink:href="wdc-20261002.xsd#SupplementalFinancialStatementDataScheduleofAccumulatedOtherComprehensiveIncomeDetails"/>
  <link:definitionLink xlink:role="http://www.wdc.com/role/SupplementalFinancialStatementDataScheduleofAccumulatedOtherComprehensiveIncomeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_01a01567-fc29-77b0-93a2-51f098fe4b55" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_01a01567-fc29-71fd-8946-80e60c5597ea" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_01a01567-fc29-77b0-93a2-51f098fe4b55" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_01a01567-fc29-71fd-8946-80e60c5597ea" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_01a01567-fc29-7676-b2c0-0aa05a275f0e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_01a01567-fc29-71fd-8946-80e60c5597ea" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_01a01567-fc29-7676-b2c0-0aa05a275f0e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_01a01567-fc29-7676-b2c0-0aa05a275f0e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_01a01567-fc29-7676-b2c0-0aa05a275f0e" xlink:to="loc_us-gaap_EquityComponentDomain_01a01567-fc29-7676-b2c0-0aa05a275f0e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_01a01567-fc29-7d8c-8475-cbed9a2b01bc" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_01a01567-fc29-7676-b2c0-0aa05a275f0e" xlink:to="loc_us-gaap_EquityComponentDomain_01a01567-fc29-7d8c-8475-cbed9a2b01bc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentNetUnamortizedGainLossMember_01a01567-fc29-7469-864c-1d4c866ea1f7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccumulatedDefinedBenefitPlansAdjustmentNetUnamortizedGainLossMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_01a01567-fc29-7d8c-8475-cbed9a2b01bc" xlink:to="loc_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentNetUnamortizedGainLossMember_01a01567-fc29-7469-864c-1d4c866ea1f7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedTranslationAdjustmentMember_01a01567-fc29-70d3-b23e-a4f0a743541d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccumulatedTranslationAdjustmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_01a01567-fc29-7d8c-8475-cbed9a2b01bc" xlink:to="loc_us-gaap_AccumulatedTranslationAdjustmentMember_01a01567-fc29-70d3-b23e-a4f0a743541d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedGainLossNetCashFlowHedgeParentMember_01a01567-fc29-707a-9b9d-248fe678471a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccumulatedGainLossNetCashFlowHedgeParentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_01a01567-fc29-7d8c-8475-cbed9a2b01bc" xlink:to="loc_us-gaap_AccumulatedGainLossNetCashFlowHedgeParentMember_01a01567-fc29-707a-9b9d-248fe678471a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_01a01567-fc29-74b1-b66c-a05e72c7bded" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_01a01567-fc29-7d8c-8475-cbed9a2b01bc" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_01a01567-fc29-74b1-b66c-a05e72c7bded" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AOCIAttributableToParentNetOfTaxRollForward_01a01567-fc29-7e4c-a373-7c60a7cdba51" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AOCIAttributableToParentNetOfTaxRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_01a01567-fc29-77b0-93a2-51f098fe4b55" xlink:to="loc_us-gaap_AOCIAttributableToParentNetOfTaxRollForward_01a01567-fc29-7e4c-a373-7c60a7cdba51" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_01a01567-fc29-70d7-86fe-77070423c44d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockholdersEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AOCIAttributableToParentNetOfTaxRollForward_01a01567-fc29-7e4c-a373-7c60a7cdba51" xlink:to="loc_us-gaap_StockholdersEquity_01a01567-fc29-70d7-86fe-77070423c44d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OciBeforeReclassificationsBeforeTaxAttributableToParent_01a01567-fc29-75b6-bac6-c0e51376a885" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OciBeforeReclassificationsBeforeTaxAttributableToParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AOCIAttributableToParentNetOfTaxRollForward_01a01567-fc29-7e4c-a373-7c60a7cdba51" xlink:to="loc_us-gaap_OciBeforeReclassificationsBeforeTaxAttributableToParent_01a01567-fc29-75b6-bac6-c0e51376a885" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReclassificationFromAociCurrentPeriodBeforeTaxAttributableToParent_01a01567-fc29-7ccf-8ae2-6817f0ff576e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ReclassificationFromAociCurrentPeriodBeforeTaxAttributableToParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AOCIAttributableToParentNetOfTaxRollForward_01a01567-fc29-7e4c-a373-7c60a7cdba51" xlink:to="loc_us-gaap_ReclassificationFromAociCurrentPeriodBeforeTaxAttributableToParent_01a01567-fc29-7ccf-8ae2-6817f0ff576e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossTaxPortionAttributableToParent1_01a01567-fc29-749a-bc99-8054f16cb54e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeLossTaxPortionAttributableToParent1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AOCIAttributableToParentNetOfTaxRollForward_01a01567-fc29-7e4c-a373-7c60a7cdba51" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossTaxPortionAttributableToParent1_01a01567-fc29-749a-bc99-8054f16cb54e" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_01a01567-fc29-7d48-accd-e57bc81d1006" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AOCIAttributableToParentNetOfTaxRollForward_01a01567-fc29-7e4c-a373-7c60a7cdba51" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_01a01567-fc29-7d48-accd-e57bc81d1006" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_01a01567-fc29-7499-aafb-3d973d1f49bf" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockholdersEquity"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.wdc.com/role/FairValueMeasurementsandInvestmentsScheduleofFinancialAssetsandLiabilitiesMeasuredatFairValueonRecurringBasisDetails" xlink:type="simple" xlink:href="wdc-20261002.xsd#FairValueMeasurementsandInvestmentsScheduleofFinancialAssetsandLiabilitiesMeasuredatFairValueonRecurringBasisDetails"/>
  <link:definitionLink xlink:role="http://www.wdc.com/role/FairValueMeasurementsandInvestmentsScheduleofFinancialAssetsandLiabilitiesMeasuredatFairValueonRecurringBasisDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_01a01567-fc29-73c7-819b-3417ba495616" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_01a01567-fc29-78bf-ae71-901aba496a97" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_01a01567-fc29-73c7-819b-3417ba495616" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_01a01567-fc29-78bf-ae71-901aba496a97" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_01a01567-fc29-7a95-bdf3-5450c53f79b6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_01a01567-fc29-78bf-ae71-901aba496a97" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_01a01567-fc29-7a95-bdf3-5450c53f79b6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_01a01567-fc29-7a95-bdf3-5450c53f79b6_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_01a01567-fc29-7a95-bdf3-5450c53f79b6" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_01a01567-fc29-7a95-bdf3-5450c53f79b6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_01a01567-fc29-7af4-a747-13dc78b9f78d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_01a01567-fc29-7a95-bdf3-5450c53f79b6" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_01a01567-fc29-7af4-a747-13dc78b9f78d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_01a01567-fc29-7cac-8237-2157cc3536a5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueInputsLevel1Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_01a01567-fc29-7af4-a747-13dc78b9f78d" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_01a01567-fc29-7cac-8237-2157cc3536a5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_01a01567-fc29-7725-adc4-fbedca93e90c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueInputsLevel2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_01a01567-fc29-7af4-a747-13dc78b9f78d" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_01a01567-fc29-7725-adc4-fbedca93e90c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_01a01567-fc29-7389-93de-36a24ddaeffd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueInputsLevel3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_01a01567-fc29-7af4-a747-13dc78b9f78d" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_01a01567-fc29-7389-93de-36a24ddaeffd" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsAbstract_01a01567-fc29-7ddf-b297-32d1e98569e7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_01a01567-fc29-73c7-819b-3417ba495616" xlink:to="loc_us-gaap_AssetsAbstract_01a01567-fc29-7ddf-b297-32d1e98569e7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsFairValueDisclosure_01a01567-fc29-7637-9f0b-ade1d22f7745" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CashAndCashEquivalentsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_01a01567-fc29-7ddf-b297-32d1e98569e7" xlink:to="loc_us-gaap_CashAndCashEquivalentsFairValueDisclosure_01a01567-fc29-7637-9f0b-ade1d22f7745" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssets_01a01567-fc29-7bce-b429-b16a927e7209" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_01a01567-fc29-7ddf-b297-32d1e98569e7" xlink:to="loc_us-gaap_DerivativeAssets_01a01567-fc29-7bce-b429-b16a927e7209" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsFairValueDisclosure_01a01567-fc29-79c8-ae2b-a473fad43011" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_01a01567-fc29-7ddf-b297-32d1e98569e7" xlink:to="loc_us-gaap_AssetsFairValueDisclosure_01a01567-fc29-79c8-ae2b-a473fad43011" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesAbstract_01a01567-fc29-78f8-849b-7529c4ffbcc2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LiabilitiesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_01a01567-fc29-73c7-819b-3417ba495616" xlink:to="loc_us-gaap_LiabilitiesAbstract_01a01567-fc29-78f8-849b-7529c4ffbcc2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilities_01a01567-fc29-7c20-9199-0115ac7f1626" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAbstract_01a01567-fc29-78f8-849b-7529c4ffbcc2" xlink:to="loc_us-gaap_DerivativeLiabilities_01a01567-fc29-7c20-9199-0115ac7f1626" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesFairValueDisclosure_01a01567-fc29-7f83-aeaa-21dcd7c692ee" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LiabilitiesFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAbstract_01a01567-fc29-78f8-849b-7529c4ffbcc2" xlink:to="loc_us-gaap_LiabilitiesFairValueDisclosure_01a01567-fc29-7f83-aeaa-21dcd7c692ee" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.wdc.com/role/FairValueMeasurementsandInvestmentsScheduleofRelatedCostsandFairValuesBasedonQuotedMarketPricesDetails" xlink:type="simple" xlink:href="wdc-20261002.xsd#FairValueMeasurementsandInvestmentsScheduleofRelatedCostsandFairValuesBasedonQuotedMarketPricesDetails"/>
  <link:definitionLink xlink:role="http://www.wdc.com/role/FairValueMeasurementsandInvestmentsScheduleofRelatedCostsandFairValuesBasedonQuotedMarketPricesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_01a01567-fc29-7099-9956-a1abfa6c4278" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_01a01567-fc29-7b04-840c-0c871adac74c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_01a01567-fc29-7099-9956-a1abfa6c4278" xlink:to="loc_us-gaap_DebtInstrumentTable_01a01567-fc29-7b04-840c-0c871adac74c" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_01a01567-fc29-7e0b-96b1-b1969b74cd76" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_01a01567-fc29-7b04-840c-0c871adac74c" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_01a01567-fc29-7e0b-96b1-b1969b74cd76" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_01a01567-fc29-7e0b-96b1-b1969b74cd76_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_01a01567-fc29-7e0b-96b1-b1969b74cd76" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_01a01567-fc29-7e0b-96b1-b1969b74cd76_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_01a01567-fc29-7519-a1b3-3bdd894e75a3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_01a01567-fc29-7e0b-96b1-b1969b74cd76" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_01a01567-fc29-7519-a1b3-3bdd894e75a3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_01a01567-fc29-7f53-aecb-5344c71b176b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueInputsLevel2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_01a01567-fc29-7519-a1b3-3bdd894e75a3" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_01a01567-fc29-7f53-aecb-5344c71b176b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementBasisAxis_01a01567-fc29-7619-8355-0fe10cdec8f2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueByMeasurementBasisAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_01a01567-fc29-7b04-840c-0c871adac74c" xlink:to="loc_us-gaap_FairValueByMeasurementBasisAxis_01a01567-fc29-7619-8355-0fe10cdec8f2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_01a01567-fc29-7619-8355-0fe10cdec8f2_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PortionAtFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementBasisAxis_01a01567-fc29-7619-8355-0fe10cdec8f2" xlink:to="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_01a01567-fc29-7619-8355-0fe10cdec8f2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueDisclosureItemAmountsDomain_01a01567-fc29-7861-a804-008bab8bea28" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueDisclosureItemAmountsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementBasisAxis_01a01567-fc29-7619-8355-0fe10cdec8f2" xlink:to="loc_us-gaap_FairValueDisclosureItemAmountsDomain_01a01567-fc29-7861-a804-008bab8bea28" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_01a01567-fc29-7d8e-8885-7e1af516011f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PortionAtFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueDisclosureItemAmountsDomain_01a01567-fc29-7861-a804-008bab8bea28" xlink:to="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_01a01567-fc29-7d8e-8885-7e1af516011f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CarryingReportedAmountFairValueDisclosureMember_01a01567-fc29-7f53-a73f-666dbb5430b8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CarryingReportedAmountFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_01a01567-fc29-7d8e-8885-7e1af516011f" xlink:to="loc_us-gaap_CarryingReportedAmountFairValueDisclosureMember_01a01567-fc29-7f53-a73f-666dbb5430b8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EstimateOfFairValueFairValueDisclosureMember_01a01567-fc29-777b-be82-ed988b5c9897" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EstimateOfFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_01a01567-fc29-7d8e-8885-7e1af516011f" xlink:to="loc_us-gaap_EstimateOfFairValueFairValueDisclosureMember_01a01567-fc29-777b-be82-ed988b5c9897" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_01a01567-fc29-7b21-9fa2-ae2fc977ba07" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_01a01567-fc29-7b04-840c-0c871adac74c" xlink:to="loc_us-gaap_DebtInstrumentAxis_01a01567-fc29-7b21-9fa2-ae2fc977ba07" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_01a01567-fc29-7b21-9fa2-ae2fc977ba07_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_01a01567-fc29-7b21-9fa2-ae2fc977ba07" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_01a01567-fc29-7b21-9fa2-ae2fc977ba07_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_01a01567-fc29-7708-8db0-63845324c5bc" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_01a01567-fc29-7b21-9fa2-ae2fc977ba07" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_01a01567-fc29-7708-8db0-63845324c5bc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_RevolvingCreditFacilityMaturingJanuary2027Member_01a03244-a8c1-7a28-b5cb-704c1c8e6ad6" xlink:href="wdc-20261002.xsd#wdc_RevolvingCreditFacilityMaturingJanuary2027Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_01a01567-fc29-7708-8db0-63845324c5bc" xlink:to="loc_wdc_RevolvingCreditFacilityMaturingJanuary2027Member_01a03244-a8c1-7a28-b5cb-704c1c8e6ad6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_ThreePointZeroZeroPercentConvertibleNotesMember_01a15741-9e53-7d05-b2d2-94a7a9d55f3e" xlink:href="wdc-20261002.xsd#wdc_ThreePointZeroZeroPercentConvertibleNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_01a01567-fc29-7708-8db0-63845324c5bc" xlink:to="loc_wdc_ThreePointZeroZeroPercentConvertibleNotesMember_01a15741-9e53-7d05-b2d2-94a7a9d55f3e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_01a01567-fc29-747b-a6c0-4e273f1bebea" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_01a01567-fc29-7b04-840c-0c871adac74c" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_01a01567-fc29-747b-a6c0-4e273f1bebea" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_01a01567-fc29-747b-a6c0-4e273f1bebea_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_01a01567-fc29-747b-a6c0-4e273f1bebea" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_01a01567-fc29-747b-a6c0-4e273f1bebea_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_01a01567-fc29-7265-a0ed-3a8898086115" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_01a01567-fc29-747b-a6c0-4e273f1bebea" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_01a01567-fc29-7265-a0ed-3a8898086115" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConvertibleDebtMember_01a01567-fc29-784e-a058-97de079882ff" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConvertibleDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_01a01567-fc29-7265-a0ed-3a8898086115" xlink:to="loc_us-gaap_ConvertibleDebtMember_01a01567-fc29-784e-a058-97de079882ff" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_01a01567-fc29-7ce2-a925-153df5b1105d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_01a01567-fc29-7099-9956-a1abfa6c4278" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_01a01567-fc29-7ce2-a925-153df5b1105d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtFairValue_01a01567-fc29-750e-b9dd-0665adf61c55" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongTermDebtFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_01a01567-fc29-7099-9956-a1abfa6c4278" xlink:to="loc_us-gaap_LongTermDebtFairValue_01a01567-fc29-750e-b9dd-0665adf61c55" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.wdc.com/role/DebtScheduleofDebtDetails" xlink:type="simple" xlink:href="wdc-20261002.xsd#DebtScheduleofDebtDetails"/>
  <link:definitionLink xlink:role="http://www.wdc.com/role/DebtScheduleofDebtDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_01a01567-fc29-73c5-a45e-fe03acbc88f3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_01a01567-fc29-7b68-be69-9f6cd563858b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_01a01567-fc29-73c5-a45e-fe03acbc88f3" xlink:to="loc_us-gaap_DebtInstrumentTable_01a01567-fc29-7b68-be69-9f6cd563858b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_01a01567-fc29-7148-ad17-c9c30272f904" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_01a01567-fc29-7b68-be69-9f6cd563858b" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_01a01567-fc29-7148-ad17-c9c30272f904" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_01a01567-fc29-7148-ad17-c9c30272f904_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_01a01567-fc29-7148-ad17-c9c30272f904" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_01a01567-fc29-7148-ad17-c9c30272f904_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_01a01567-fc29-712b-ae09-44478a37aa04" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_01a01567-fc29-7148-ad17-c9c30272f904" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_01a01567-fc29-712b-ae09-44478a37aa04" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConvertibleDebtMember_01a01567-fc29-74dd-b396-fe511df3c6db" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConvertibleDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_01a01567-fc29-712b-ae09-44478a37aa04" xlink:to="loc_us-gaap_ConvertibleDebtMember_01a01567-fc29-74dd-b396-fe511df3c6db" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_01a01567-fc29-7b8b-a8b4-5e746aa92d98" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_01a01567-fc29-7b68-be69-9f6cd563858b" xlink:to="loc_us-gaap_DebtInstrumentAxis_01a01567-fc29-7b8b-a8b4-5e746aa92d98" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_01a01567-fc29-7b8b-a8b4-5e746aa92d98_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_01a01567-fc29-7b8b-a8b4-5e746aa92d98" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_01a01567-fc29-7b8b-a8b4-5e746aa92d98_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_01a01567-fc29-7dd0-822a-d5141c367e0f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_01a01567-fc29-7b8b-a8b4-5e746aa92d98" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_01a01567-fc29-7dd0-822a-d5141c367e0f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_RevolvingCreditFacilityMaturingJanuary2027Member_01a0324d-8641-7c62-88d4-0e3d4ba55cb6" xlink:href="wdc-20261002.xsd#wdc_RevolvingCreditFacilityMaturingJanuary2027Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_01a01567-fc29-7dd0-822a-d5141c367e0f" xlink:to="loc_wdc_RevolvingCreditFacilityMaturingJanuary2027Member_01a0324d-8641-7c62-88d4-0e3d4ba55cb6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_ThreePointZeroZeroPercentConvertibleNotesMember_01a0b227-9a14-7d75-bd1f-6ff9391830bb" xlink:href="wdc-20261002.xsd#wdc_ThreePointZeroZeroPercentConvertibleNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_01a01567-fc29-7dd0-822a-d5141c367e0f" xlink:to="loc_wdc_ThreePointZeroZeroPercentConvertibleNotesMember_01a0b227-9a14-7d75-bd1f-6ff9391830bb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_01a01567-fc29-7fd1-bf99-dea2e21ab069" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_01a01567-fc29-73c5-a45e-fe03acbc88f3" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_01a01567-fc29-7fd1-bf99-dea2e21ab069" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentCarryingAmount_01a01567-fc29-7e37-942c-0feae9c58f21" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentCarryingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_01a01567-fc29-73c5-a45e-fe03acbc88f3" xlink:to="loc_us-gaap_DebtInstrumentCarryingAmount_01a01567-fc29-7e37-942c-0feae9c58f21" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet_01a01567-fc29-7bf1-97b8-0fb7fb7995d8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_01a01567-fc29-73c5-a45e-fe03acbc88f3" xlink:to="loc_us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet_01a01567-fc29-7bf1-97b8-0fb7fb7995d8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtCurrent_01a01567-fc29-7573-8f13-23253f6f8798" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongTermDebtCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_01a01567-fc29-73c5-a45e-fe03acbc88f3" xlink:to="loc_us-gaap_LongTermDebtCurrent_01a01567-fc29-7573-8f13-23253f6f8798" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.wdc.com/role/DebtAdditionalInformationDetails" xlink:type="simple" xlink:href="wdc-20261002.xsd#DebtAdditionalInformationDetails"/>
  <link:definitionLink xlink:role="http://www.wdc.com/role/DebtAdditionalInformationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_01a0b284-3be2-7713-9611-89d767af7651" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_01a01567-fc29-7094-8c53-e01c672b6c5c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_01a0b284-3be2-7713-9611-89d767af7651" xlink:to="loc_us-gaap_DebtInstrumentTable_01a01567-fc29-7094-8c53-e01c672b6c5c" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_01a0b284-3be2-7dc5-ac88-816b5c378c3f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_01a01567-fc29-7094-8c53-e01c672b6c5c" xlink:to="loc_us-gaap_CreditFacilityAxis_01a0b284-3be2-7dc5-ac88-816b5c378c3f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_01a0b284-3be2-7dc5-ac88-816b5c378c3f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_01a0b284-3be2-7dc5-ac88-816b5c378c3f" xlink:to="loc_us-gaap_CreditFacilityDomain_01a0b284-3be2-7dc5-ac88-816b5c378c3f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_01a0b284-3be2-7db4-a2aa-adc985582361" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_01a0b284-3be2-7dc5-ac88-816b5c378c3f" xlink:to="loc_us-gaap_CreditFacilityDomain_01a0b284-3be2-7db4-a2aa-adc985582361" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_01a0b284-3be2-7853-bad6-98a2b8848acf" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_01a0b284-3be2-7db4-a2aa-adc985582361" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_01a0b284-3be2-7853-bad6-98a2b8848acf" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StandbyLettersOfCreditMember_01a0b284-3be2-72bb-ac00-cbaf8203b230" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StandbyLettersOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_01a0b284-3be2-7db4-a2aa-adc985582361" xlink:to="loc_us-gaap_StandbyLettersOfCreditMember_01a0b284-3be2-72bb-ac00-cbaf8203b230" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_01a0b284-3be2-77de-9f6e-6f08732ad467" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_01a01567-fc29-7094-8c53-e01c672b6c5c" xlink:to="loc_us-gaap_DebtInstrumentAxis_01a0b284-3be2-77de-9f6e-6f08732ad467" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_01a0b284-3be2-77de-9f6e-6f08732ad467_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_01a0b284-3be2-77de-9f6e-6f08732ad467" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_01a0b284-3be2-77de-9f6e-6f08732ad467_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_01a0b284-3be2-723d-80d4-b5fba08c37ac" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_01a0b284-3be2-77de-9f6e-6f08732ad467" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_01a0b284-3be2-723d-80d4-b5fba08c37ac" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_RevolvingCreditFacilityMaturingJanuary2027Member_01a0b284-3be2-76d1-8f2a-e143507580d5" xlink:href="wdc-20261002.xsd#wdc_RevolvingCreditFacilityMaturingJanuary2027Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_01a0b284-3be2-723d-80d4-b5fba08c37ac" xlink:to="loc_wdc_RevolvingCreditFacilityMaturingJanuary2027Member_01a0b284-3be2-76d1-8f2a-e143507580d5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_TermLoanA3Member_01a0b284-3be2-7c4c-9d3b-7315d8d5774d" xlink:href="wdc-20261002.xsd#wdc_TermLoanA3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_01a0b284-3be2-723d-80d4-b5fba08c37ac" xlink:to="loc_wdc_TermLoanA3Member_01a0b284-3be2-7c4c-9d3b-7315d8d5774d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_ThreePointZeroZeroPercentConvertibleNotesMember_01a0b284-3be2-7b74-b889-ef90b26183b2" xlink:href="wdc-20261002.xsd#wdc_ThreePointZeroZeroPercentConvertibleNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_01a0b284-3be2-723d-80d4-b5fba08c37ac" xlink:to="loc_wdc_ThreePointZeroZeroPercentConvertibleNotesMember_01a0b284-3be2-7b74-b889-ef90b26183b2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_ThreePointZeroZeroPercentConvertibleNotesDueTwoThousandTwentyEightMember_01a0b289-571c-7452-aa94-5d36ff726d72" xlink:href="wdc-20261002.xsd#wdc_ThreePointZeroZeroPercentConvertibleNotesDueTwoThousandTwentyEightMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_01a0b284-3be2-723d-80d4-b5fba08c37ac" xlink:to="loc_wdc_ThreePointZeroZeroPercentConvertibleNotesDueTwoThousandTwentyEightMember_01a0b289-571c-7452-aa94-5d36ff726d72" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_01a0b284-3be2-7d50-80cb-4238acbe594b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_01a01567-fc29-7094-8c53-e01c672b6c5c" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_01a0b284-3be2-7d50-80cb-4238acbe594b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_01a0b284-3be2-7d50-80cb-4238acbe594b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_01a0b284-3be2-7d50-80cb-4238acbe594b" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_01a0b284-3be2-7d50-80cb-4238acbe594b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_01a0b284-3be2-7a45-971f-26ce0427fd97" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_01a0b284-3be2-7d50-80cb-4238acbe594b" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_01a0b284-3be2-7a45-971f-26ce0427fd97" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConvertibleDebtMember_01a0b284-3be2-7578-80dd-cba36abe0272" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConvertibleDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_01a0b284-3be2-7a45-971f-26ce0427fd97" xlink:to="loc_us-gaap_ConvertibleDebtMember_01a0b284-3be2-7578-80dd-cba36abe0272" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeniorNotesMember_01a0b284-3be2-7194-b02b-b4394a9be8bd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SeniorNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_01a0b284-3be2-7a45-971f-26ce0427fd97" xlink:to="loc_us-gaap_SeniorNotesMember_01a0b284-3be2-7194-b02b-b4394a9be8bd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_01a0b284-3be2-70eb-a439-6ad477ec3f0e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_01a01567-fc29-7094-8c53-e01c672b6c5c" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_01a0b284-3be2-70eb-a439-6ad477ec3f0e" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_01a0b284-3be2-70eb-a439-6ad477ec3f0e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_01a0b284-3be2-70eb-a439-6ad477ec3f0e" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_01a0b284-3be2-70eb-a439-6ad477ec3f0e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_01a0b284-3be2-75f4-bdf3-2c457a8934bc" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_01a0b284-3be2-70eb-a439-6ad477ec3f0e" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_01a0b284-3be2-75f4-bdf3-2c457a8934bc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_CappedCallsMember_01a0b284-3be2-75a6-a692-11a85f0fcee2" xlink:href="wdc-20261002.xsd#wdc_CappedCallsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_01a0b284-3be2-75f4-bdf3-2c457a8934bc" xlink:to="loc_wdc_CappedCallsMember_01a0b284-3be2-75a6-a692-11a85f0fcee2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentCarryingAmount_01a0b284-3be2-7c0e-8323-37a888efead5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentCarryingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_01a0b284-3be2-7713-9611-89d767af7651" xlink:to="loc_us-gaap_DebtInstrumentCarryingAmount_01a0b284-3be2-7c0e-8323-37a888efead5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromLinesOfCredit_01a0b284-3be2-7334-9adb-a7487ec7f1ae" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProceedsFromLinesOfCredit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_01a0b284-3be2-7713-9611-89d767af7651" xlink:to="loc_us-gaap_ProceedsFromLinesOfCredit_01a0b284-3be2-7334-9adb-a7487ec7f1ae" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RepaymentsOfLinesOfCredit_01a0b284-3be2-7bb8-a90f-71d1386c0991" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RepaymentsOfLinesOfCredit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_01a0b284-3be2-7713-9611-89d767af7651" xlink:to="loc_us-gaap_RepaymentsOfLinesOfCredit_01a0b284-3be2-7bb8-a90f-71d1386c0991" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermBorrowings_01a0b284-3be2-7a5d-ae81-9dd3c465f805" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShortTermBorrowings"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_01a0b284-3be2-7713-9611-89d767af7651" xlink:to="loc_us-gaap_ShortTermBorrowings_01a0b284-3be2-7a5d-ae81-9dd3c465f805" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount_01a0b284-3be2-78f3-b957-ef59015cab46" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentFaceAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_01a0b284-3be2-7713-9611-89d767af7651" xlink:to="loc_us-gaap_DebtInstrumentFaceAmount_01a0b284-3be2-78f3-b957-ef59015cab46" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity_01a1403e-97b6-7c4f-97a2-8ffac63edda4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_01a0b284-3be2-7713-9611-89d767af7651" xlink:to="loc_us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity_01a1403e-97b6-7c4f-97a2-8ffac63edda4" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RepaymentsOfLongTermDebt_01a0b284-3be2-7182-8f95-52964ccf6a12" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RepaymentsOfLongTermDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_01a0b284-3be2-7713-9611-89d767af7651" xlink:to="loc_us-gaap_RepaymentsOfLongTermDebt_01a0b284-3be2-7182-8f95-52964ccf6a12" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_01a0b284-3be2-7e1b-bc88-f28ff89847fe" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_01a0b284-3be2-7713-9611-89d767af7651" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_01a0b284-3be2-7e1b-bc88-f28ff89847fe" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ExtinguishmentOfDebtAmount_01a0b284-3be2-7872-a50c-5df454404efd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ExtinguishmentOfDebtAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_01a0b284-3be2-7713-9611-89d767af7651" xlink:to="loc_us-gaap_ExtinguishmentOfDebtAmount_01a0b284-3be2-7872-a50c-5df454404efd" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtConversionConvertedInstrumentSharesIssued1_01a0b284-3be2-718c-a80c-78cec50fcff7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtConversionConvertedInstrumentSharesIssued1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_01a0b284-3be2-7713-9611-89d767af7651" xlink:to="loc_us-gaap_DebtConversionConvertedInstrumentSharesIssued1_01a0b284-3be2-718c-a80c-78cec50fcff7" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtConversionConvertedInstrumentAmount1_01a0b284-3be2-7331-b541-2e3b5c9a0bbe" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtConversionConvertedInstrumentAmount1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_01a0b284-3be2-7713-9611-89d767af7651" xlink:to="loc_us-gaap_DebtConversionConvertedInstrumentAmount1_01a0b284-3be2-7331-b541-2e3b5c9a0bbe" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WriteOffOfDeferredDebtIssuanceCost_01a0b284-3be2-7cff-ad08-abe109ca18f1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_WriteOffOfDeferredDebtIssuanceCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_01a0b284-3be2-7713-9611-89d767af7651" xlink:to="loc_us-gaap_WriteOffOfDeferredDebtIssuanceCost_01a0b284-3be2-7cff-ad08-abe109ca18f1" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConvertibleDebt_01a14045-6273-75ec-b672-d4be4526e368" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConvertibleDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_01a0b284-3be2-7713-9611-89d767af7651" xlink:to="loc_us-gaap_ConvertibleDebt_01a14045-6273-75ec-b672-d4be4526e368" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentConvertibleConversionPrice1_01a1403c-1c5f-7145-95f1-90f9dbd06b11" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentConvertibleConversionPrice1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_01a0b284-3be2-7713-9611-89d767af7651" xlink:to="loc_us-gaap_DebtInstrumentConvertibleConversionPrice1_01a1403c-1c5f-7145-95f1-90f9dbd06b11" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeNotionalAmount_01a0b284-3be2-7168-89d1-e5ea5dddadf1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeNotionalAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_01a0b284-3be2-7713-9611-89d767af7651" xlink:to="loc_us-gaap_DerivativeNotionalAmount_01a0b284-3be2-7168-89d1-e5ea5dddadf1" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeCapPrice_01a0b284-3be2-714b-8c75-caefe114a20b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeCapPrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_01a0b284-3be2-7713-9611-89d767af7651" xlink:to="loc_us-gaap_DerivativeCapPrice_01a0b284-3be2-714b-8c75-caefe114a20b" xlink:type="arc" order="15"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.wdc.com/role/IncomeTaxesAdditionalInformationDetails" xlink:type="simple" xlink:href="wdc-20261002.xsd#IncomeTaxesAdditionalInformationDetails"/>
  <link:definitionLink xlink:role="http://www.wdc.com/role/IncomeTaxesAdditionalInformationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExaminationLineItems_01a0a8a7-6901-779d-89ef-292f5b74d78a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeTaxExaminationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExaminationTable_01a0a8a6-e9f5-79ad-9c71-1f573e4f265f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeTaxExaminationTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_IncomeTaxExaminationLineItems_01a0a8a7-6901-779d-89ef-292f5b74d78a" xlink:to="loc_us-gaap_IncomeTaxExaminationTable_01a0a8a6-e9f5-79ad-9c71-1f573e4f265f" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TaxPeriodAxis_01a0a8a7-def3-74bd-b0ae-faea0b8728cf" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TaxPeriodAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeTaxExaminationTable_01a0a8a6-e9f5-79ad-9c71-1f573e4f265f" xlink:to="loc_us-gaap_TaxPeriodAxis_01a0a8a7-def3-74bd-b0ae-faea0b8728cf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TaxPeriodDomain_01a0a8a7-def3-74bd-b0ae-faea0b8728cf_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TaxPeriodDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_TaxPeriodAxis_01a0a8a7-def3-74bd-b0ae-faea0b8728cf" xlink:to="loc_us-gaap_TaxPeriodDomain_01a0a8a7-def3-74bd-b0ae-faea0b8728cf_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TaxPeriodDomain_01a0a8a7-def3-7008-851a-b962702624af" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TaxPeriodDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_TaxPeriodAxis_01a0a8a7-def3-74bd-b0ae-faea0b8728cf" xlink:to="loc_us-gaap_TaxPeriodDomain_01a0a8a7-def3-7008-851a-b962702624af" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_TaxYears2008Through2015Member_01a0a8a8-297b-7af1-ba16-71891a3d8ecb" xlink:href="wdc-20261002.xsd#wdc_TaxYears2008Through2015Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TaxPeriodDomain_01a0a8a7-def3-7008-851a-b962702624af" xlink:to="loc_wdc_TaxYears2008Through2015Member_01a0a8a8-297b-7af1-ba16-71891a3d8ecb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued_01a01567-fc29-76b1-b4d9-59254523b4bf" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxExaminationLineItems_01a0a8a7-6901-779d-89ef-292f5b74d78a" xlink:to="loc_us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued_01a01567-fc29-76b1-b4d9-59254523b4bf" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_UnrecognizedTaxBenefitsPayable_01a01567-fc29-7f72-b7d0-55628543c09d" xlink:href="wdc-20261002.xsd#wdc_UnrecognizedTaxBenefitsPayable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxExaminationLineItems_01a0a8a7-6901-779d-89ef-292f5b74d78a" xlink:to="loc_wdc_UnrecognizedTaxBenefitsPayable_01a01567-fc29-7f72-b7d0-55628543c09d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_UnrecognizedTaxBenefitsMandatoryDeemedRepatriationLiability_01a0a8a6-4a3d-7e49-adc0-1a63f40a95e3" xlink:href="wdc-20261002.xsd#wdc_UnrecognizedTaxBenefitsMandatoryDeemedRepatriationLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxExaminationLineItems_01a0a8a7-6901-779d-89ef-292f5b74d78a" xlink:to="loc_wdc_UnrecognizedTaxBenefitsMandatoryDeemedRepatriationLiability_01a0a8a6-4a3d-7e49-adc0-1a63f40a95e3" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.wdc.com/role/BusinessRealignmentChargesExpenseRecognitionDetails" xlink:type="simple" xlink:href="wdc-20261002.xsd#BusinessRealignmentChargesExpenseRecognitionDetails"/>
  <link:definitionLink xlink:role="http://www.wdc.com/role/BusinessRealignmentChargesExpenseRecognitionDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCostAndReserveLineItems_01a01567-fc29-7633-baaa-b4ed4c31dded" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringCostAndReserveLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_01a01567-fc29-7580-9448-7c8ca3352d00" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfRestructuringAndRelatedCostsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_01a01567-fc29-7633-baaa-b4ed4c31dded" xlink:to="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_01a01567-fc29-7580-9448-7c8ca3352d00" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringPlanAxis_01a01567-fc29-7d91-a7e7-2f708a1ee434" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringPlanAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_01a01567-fc29-7580-9448-7c8ca3352d00" xlink:to="loc_us-gaap_RestructuringPlanAxis_01a01567-fc29-7d91-a7e7-2f708a1ee434" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringPlanDomain_01a01567-fc29-7d91-a7e7-2f708a1ee434_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringPlanDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RestructuringPlanAxis_01a01567-fc29-7d91-a7e7-2f708a1ee434" xlink:to="loc_us-gaap_RestructuringPlanDomain_01a01567-fc29-7d91-a7e7-2f708a1ee434_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringPlanDomain_01a01567-fc29-74ce-9214-716b64050d80" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringPlanDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RestructuringPlanAxis_01a01567-fc29-7d91-a7e7-2f708a1ee434" xlink:to="loc_us-gaap_RestructuringPlanDomain_01a01567-fc29-74ce-9214-716b64050d80" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_BusinessRealignmentActivitiesMember_01a01567-fc29-7bbf-9b03-2111d5c88ee9" xlink:href="wdc-20261002.xsd#wdc_BusinessRealignmentActivitiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringPlanDomain_01a01567-fc29-74ce-9214-716b64050d80" xlink:to="loc_wdc_BusinessRealignmentActivitiesMember_01a01567-fc29-7bbf-9b03-2111d5c88ee9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_CashBasedEmployeeTerminationBenefitsAndOtherContractTerminationCosts_01a01567-fc29-7cba-a884-b8ea7bb921cc" xlink:href="wdc-20261002.xsd#wdc_CashBasedEmployeeTerminationBenefitsAndOtherContractTerminationCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_01a01567-fc29-7633-baaa-b4ed4c31dded" xlink:to="loc_wdc_CashBasedEmployeeTerminationBenefitsAndOtherContractTerminationCosts_01a01567-fc29-7cba-a884-b8ea7bb921cc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAcceleratedCompensationCost_01a01567-fc29-7c0e-80ee-28b2fe2ed5cb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAcceleratedCompensationCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_01a01567-fc29-7633-baaa-b4ed4c31dded" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAcceleratedCompensationCost_01a01567-fc29-7c0e-80ee-28b2fe2ed5cb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_BusinessRealignmentCharges_01a01567-fc29-776d-92b1-2ed84f9793c6" xlink:href="wdc-20261002.xsd#wdc_BusinessRealignmentCharges"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_01a01567-fc29-7633-baaa-b4ed4c31dded" xlink:to="loc_wdc_BusinessRealignmentCharges_01a01567-fc29-776d-92b1-2ed84f9793c6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeveranceCosts1_01a01567-fc29-7b77-ab3e-beb49b6433d5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SeveranceCosts1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_01a01567-fc29-7633-baaa-b4ed4c31dded" xlink:to="loc_us-gaap_SeveranceCosts1_01a01567-fc29-7b77-ab3e-beb49b6433d5" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.wdc.com/role/BusinessRealignmentChargesBusinessRealignmentActivitiesDetails" xlink:type="simple" xlink:href="wdc-20261002.xsd#BusinessRealignmentChargesBusinessRealignmentActivitiesDetails"/>
  <link:definitionLink xlink:role="http://www.wdc.com/role/BusinessRealignmentChargesBusinessRealignmentActivitiesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCostAndReserveLineItems_01a01567-fc29-7331-bcf2-9d07fd3b8216" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringCostAndReserveLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_01a01567-fc29-7ff5-9b0d-819ea780eda7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfRestructuringAndRelatedCostsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_01a01567-fc29-7331-bcf2-9d07fd3b8216" xlink:to="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_01a01567-fc29-7ff5-9b0d-819ea780eda7" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCostAndReserveAxis_01a01567-fc29-76b8-97ae-b6b6f8237c39" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringCostAndReserveAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_01a01567-fc29-7ff5-9b0d-819ea780eda7" xlink:to="loc_us-gaap_RestructuringCostAndReserveAxis_01a01567-fc29-76b8-97ae-b6b6f8237c39" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfRestructuringDomain_01a01567-fc29-76b8-97ae-b6b6f8237c39_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TypeOfRestructuringDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RestructuringCostAndReserveAxis_01a01567-fc29-76b8-97ae-b6b6f8237c39" xlink:to="loc_us-gaap_TypeOfRestructuringDomain_01a01567-fc29-76b8-97ae-b6b6f8237c39_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfRestructuringDomain_01a01567-fc29-7c54-9232-94bd0f45770b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TypeOfRestructuringDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RestructuringCostAndReserveAxis_01a01567-fc29-76b8-97ae-b6b6f8237c39" xlink:to="loc_us-gaap_TypeOfRestructuringDomain_01a01567-fc29-7c54-9232-94bd0f45770b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OneTimeTerminationBenefitsMember_01a01567-fc29-7a73-a500-ae761976d101" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OneTimeTerminationBenefitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfRestructuringDomain_01a01567-fc29-7c54-9232-94bd0f45770b" xlink:to="loc_us-gaap_OneTimeTerminationBenefitsMember_01a01567-fc29-7a73-a500-ae761976d101" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractTerminationMember_01a01567-fc29-77de-9d00-a225ea94db3d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ContractTerminationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfRestructuringDomain_01a01567-fc29-7c54-9232-94bd0f45770b" xlink:to="loc_us-gaap_ContractTerminationMember_01a01567-fc29-77de-9d00-a225ea94db3d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringPlanAxis_01a01567-fc29-70d3-944a-542456b0062b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringPlanAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_01a01567-fc29-7ff5-9b0d-819ea780eda7" xlink:to="loc_us-gaap_RestructuringPlanAxis_01a01567-fc29-70d3-944a-542456b0062b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringPlanDomain_01a01567-fc29-70d3-944a-542456b0062b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringPlanDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RestructuringPlanAxis_01a01567-fc29-70d3-944a-542456b0062b" xlink:to="loc_us-gaap_RestructuringPlanDomain_01a01567-fc29-70d3-944a-542456b0062b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringPlanDomain_01a01567-fc29-7ec4-bb39-d8b94459e4c3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringPlanDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RestructuringPlanAxis_01a01567-fc29-70d3-944a-542456b0062b" xlink:to="loc_us-gaap_RestructuringPlanDomain_01a01567-fc29-7ec4-bb39-d8b94459e4c3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_BusinessRealignmentActivitiesMember_01a01567-fc29-7360-b9ef-48f3587a55e2" xlink:href="wdc-20261002.xsd#wdc_BusinessRealignmentActivitiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringPlanDomain_01a01567-fc29-7ec4-bb39-d8b94459e4c3" xlink:to="loc_wdc_BusinessRealignmentActivitiesMember_01a01567-fc29-7360-b9ef-48f3587a55e2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringReserveRollForward_01a01567-fc29-73f0-b6e8-f929d7cdea38" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringReserveRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_01a01567-fc29-7331-bcf2-9d07fd3b8216" xlink:to="loc_us-gaap_RestructuringReserveRollForward_01a01567-fc29-73f0-b6e8-f929d7cdea38" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringReserve_01a01567-fc29-791d-8095-982d45c8d099" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringReserve"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringReserveRollForward_01a01567-fc29-73f0-b6e8-f929d7cdea38" xlink:to="loc_us-gaap_RestructuringReserve_01a01567-fc29-791d-8095-982d45c8d099" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCharges_01a01567-fc29-77a7-be18-35b58c5f49c8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringCharges"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringReserveRollForward_01a01567-fc29-73f0-b6e8-f929d7cdea38" xlink:to="loc_us-gaap_RestructuringCharges_01a01567-fc29-77a7-be18-35b58c5f49c8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringReserve_01a01567-fc29-7e78-a521-d138149888cc" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringReserve"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.wdc.com/role/ShareholdersEquityandConvertiblePreferredStockScheduleofStockBasedCompensationExpenseDetails" xlink:type="simple" xlink:href="wdc-20261002.xsd#ShareholdersEquityandConvertiblePreferredStockScheduleofStockBasedCompensationExpenseDetails"/>
  <link:definitionLink xlink:role="http://www.wdc.com/role/ShareholdersEquityandConvertiblePreferredStockScheduleofStockBasedCompensationExpenseDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_01a01567-fccb-79ce-bc7e-f30059f907ac" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_01a01567-fccb-7499-bed8-f91e63e45c90" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_01a01567-fccb-79ce-bc7e-f30059f907ac" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_01a01567-fccb-7499-bed8-f91e63e45c90" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_01a01567-fccb-7eae-9b2d-c9722b5b0115" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_01a01567-fccb-7499-bed8-f91e63e45c90" xlink:to="loc_us-gaap_AwardTypeAxis_01a01567-fccb-7eae-9b2d-c9722b5b0115" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_01a01567-fccb-7eae-9b2d-c9722b5b0115_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_01a01567-fccb-7eae-9b2d-c9722b5b0115" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_01a01567-fccb-7eae-9b2d-c9722b5b0115_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_01a01567-fccb-7149-baba-5715bbd96c49" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_01a01567-fccb-7eae-9b2d-c9722b5b0115" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_01a01567-fccb-7149-baba-5715bbd96c49" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_RestrictedStockUnitsAndPerformanceStockUnitsMember_01a01567-fccb-7ef1-a6ab-d1d41c1202dd" xlink:href="wdc-20261002.xsd#wdc_RestrictedStockUnitsAndPerformanceStockUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_01a01567-fccb-7149-baba-5715bbd96c49" xlink:to="loc_wdc_RestrictedStockUnitsAndPerformanceStockUnitsMember_01a01567-fccb-7ef1-a6ab-d1d41c1202dd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_EmployeeStockPurchasePlanMember_01a01567-fccb-71c3-9161-49313a85c349" xlink:href="wdc-20261002.xsd#wdc_EmployeeStockPurchasePlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_01a01567-fccb-7149-baba-5715bbd96c49" xlink:to="loc_wdc_EmployeeStockPurchasePlanMember_01a01567-fccb-71c3-9161-49313a85c349" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementOfIncomeLocationBalanceAxis_01a01567-fccb-74cb-8028-ce3b69163a7b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementOfIncomeLocationBalanceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_01a01567-fccb-7499-bed8-f91e63e45c90" xlink:to="loc_us-gaap_StatementOfIncomeLocationBalanceAxis_01a01567-fccb-74cb-8028-ce3b69163a7b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense_01a01567-fccb-76c7-bbe6-287b37583455" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AllocatedShareBasedCompensationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_01a01567-fccb-79ce-bc7e-f30059f907ac" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpense_01a01567-fccb-76c7-bbe6-287b37583455" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense_01a01567-fccb-7db8-8877-f172e21cb010" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_01a01567-fccb-79ce-bc7e-f30059f907ac" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense_01a01567-fccb-7db8-8877-f172e21cb010" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpenseNetOfTax_01a01567-fccb-70cd-b7c9-e09f1a438619" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AllocatedShareBasedCompensationExpenseNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_01a01567-fccb-79ce-bc7e-f30059f907ac" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpenseNetOfTax_01a01567-fccb-70cd-b7c9-e09f1a438619" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.wdc.com/role/ShareholdersEquityandConvertiblePreferredStockScheduleofStockBasedCompensationExpenseDetails_1" xlink:type="simple" xlink:href="wdc-20261002.xsd#ShareholdersEquityandConvertiblePreferredStockScheduleofStockBasedCompensationExpenseDetails_1"/>
  <link:definitionLink xlink:role="http://www.wdc.com/role/ShareholdersEquityandConvertiblePreferredStockScheduleofStockBasedCompensationExpenseDetails_1" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_01a01567-fccb-79ce-bc7e-f30059f907ac" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_01a01567-fccb-7499-bed8-f91e63e45c90" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_01a01567-fccb-79ce-bc7e-f30059f907ac" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_01a01567-fccb-7499-bed8-f91e63e45c90" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_01a01567-fccb-7eae-9b2d-c9722b5b0115" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_01a01567-fccb-7499-bed8-f91e63e45c90" xlink:to="loc_us-gaap_AwardTypeAxis_01a01567-fccb-7eae-9b2d-c9722b5b0115" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_01a01567-fccb-7eae-9b2d-c9722b5b0115_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_01a01567-fccb-7eae-9b2d-c9722b5b0115" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_01a01567-fccb-7eae-9b2d-c9722b5b0115_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_01a01567-fccb-7149-baba-5715bbd96c49" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_01a01567-fccb-7eae-9b2d-c9722b5b0115" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_01a01567-fccb-7149-baba-5715bbd96c49" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_RestrictedStockUnitsAndPerformanceStockUnitsMember_01a01567-fccb-7ef1-a6ab-d1d41c1202dd" xlink:href="wdc-20261002.xsd#wdc_RestrictedStockUnitsAndPerformanceStockUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_01a01567-fccb-7149-baba-5715bbd96c49" xlink:to="loc_wdc_RestrictedStockUnitsAndPerformanceStockUnitsMember_01a01567-fccb-7ef1-a6ab-d1d41c1202dd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_EmployeeStockPurchasePlanMember_01a01567-fccb-71c3-9161-49313a85c349" xlink:href="wdc-20261002.xsd#wdc_EmployeeStockPurchasePlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_01a01567-fccb-7149-baba-5715bbd96c49" xlink:to="loc_wdc_EmployeeStockPurchasePlanMember_01a01567-fccb-71c3-9161-49313a85c349" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense_01a01567-fccb-76c7-bbe6-287b37583455" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AllocatedShareBasedCompensationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_01a01567-fccb-79ce-bc7e-f30059f907ac" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpense_01a01567-fccb-76c7-bbe6-287b37583455" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense_01a01567-fccb-7db8-8877-f172e21cb010" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_01a01567-fccb-79ce-bc7e-f30059f907ac" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense_01a01567-fccb-7db8-8877-f172e21cb010" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpenseNetOfTax_01a01567-fccb-70cd-b7c9-e09f1a438619" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AllocatedShareBasedCompensationExpenseNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_01a01567-fccb-79ce-bc7e-f30059f907ac" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpenseNetOfTax_01a01567-fccb-70cd-b7c9-e09f1a438619" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.wdc.com/role/ShareholdersEquityandConvertiblePreferredStockScheduleofEmployeeServiceSharebasedCompensationUnrecognizedCostsDetails" xlink:type="simple" xlink:href="wdc-20261002.xsd#ShareholdersEquityandConvertiblePreferredStockScheduleofEmployeeServiceSharebasedCompensationUnrecognizedCostsDetails"/>
  <link:definitionLink xlink:role="http://www.wdc.com/role/ShareholdersEquityandConvertiblePreferredStockScheduleofEmployeeServiceSharebasedCompensationUnrecognizedCostsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_01a01567-fccb-7983-b2c8-6f8f1f7286dd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_01a01567-fccb-7268-a7ac-040a3a9d5654" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_01a01567-fccb-7983-b2c8-6f8f1f7286dd" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_01a01567-fccb-7268-a7ac-040a3a9d5654" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_01a01567-fccb-793a-ba33-fc09eac157da" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_01a01567-fccb-7268-a7ac-040a3a9d5654" xlink:to="loc_us-gaap_AwardTypeAxis_01a01567-fccb-793a-ba33-fc09eac157da" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_01a01567-fccb-793a-ba33-fc09eac157da_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_01a01567-fccb-793a-ba33-fc09eac157da" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_01a01567-fccb-793a-ba33-fc09eac157da_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_01a01567-fccb-704e-a362-46a336f05e16" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_01a01567-fccb-793a-ba33-fc09eac157da" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_01a01567-fccb-704e-a362-46a336f05e16" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_RestrictedStockUnitsAndPerformanceStockUnitsMember_01a01567-fccb-70b8-8c83-396f43e4d23f" xlink:href="wdc-20261002.xsd#wdc_RestrictedStockUnitsAndPerformanceStockUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_01a01567-fccb-704e-a362-46a336f05e16" xlink:to="loc_wdc_RestrictedStockUnitsAndPerformanceStockUnitsMember_01a01567-fccb-70b8-8c83-396f43e4d23f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_EmployeeStockPurchasePlanMember_01a01567-fccb-714e-94f6-865df8df57e5" xlink:href="wdc-20261002.xsd#wdc_EmployeeStockPurchasePlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_01a01567-fccb-704e-a362-46a336f05e16" xlink:to="loc_wdc_EmployeeStockPurchasePlanMember_01a01567-fccb-714e-94f6-865df8df57e5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_01a01567-fccb-7412-befc-cee5e638076f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_01a01567-fccb-7983-b2c8-6f8f1f7286dd" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_01a01567-fccb-7412-befc-cee5e638076f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_01a01567-fccb-74ab-bb08-6f0fc5ee3860" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_01a01567-fccb-7983-b2c8-6f8f1f7286dd" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_01a01567-fccb-74ab-bb08-6f0fc5ee3860" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.wdc.com/role/ShareholdersEquityandConvertiblePreferredStockScheduleofRSUsandPSUsDetails" xlink:type="simple" xlink:href="wdc-20261002.xsd#ShareholdersEquityandConvertiblePreferredStockScheduleofRSUsandPSUsDetails"/>
  <link:definitionLink xlink:role="http://www.wdc.com/role/ShareholdersEquityandConvertiblePreferredStockScheduleofRSUsandPSUsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_01a01567-fccb-753c-ae60-51400a7ae35a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_01a01567-fccb-7294-903a-8424bf0cefc2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_01a01567-fccb-753c-ae60-51400a7ae35a" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_01a01567-fccb-7294-903a-8424bf0cefc2" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_01a01567-fccb-7771-9686-b3990b216dd1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_01a01567-fccb-7294-903a-8424bf0cefc2" xlink:to="loc_us-gaap_AwardTypeAxis_01a01567-fccb-7771-9686-b3990b216dd1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_01a01567-fccb-7771-9686-b3990b216dd1_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_01a01567-fccb-7771-9686-b3990b216dd1" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_01a01567-fccb-7771-9686-b3990b216dd1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_01a01567-fccb-7895-a2af-a2a1719fa3fc" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_01a01567-fccb-7771-9686-b3990b216dd1" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_01a01567-fccb-7895-a2af-a2a1719fa3fc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_RestrictedStockUnitsAndPerformanceShareUnitsMember_01a01567-fccb-7cd0-ba3e-b567b04b9580" xlink:href="wdc-20261002.xsd#wdc_RestrictedStockUnitsAndPerformanceShareUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_01a01567-fccb-7895-a2af-a2a1719fa3fc" xlink:to="loc_wdc_RestrictedStockUnitsAndPerformanceShareUnitsMember_01a01567-fccb-7cd0-ba3e-b567b04b9580" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_01a01567-fccb-7ad3-926e-1bcbefbed111" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_01a01567-fccb-753c-ae60-51400a7ae35a" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_01a01567-fccb-7ad3-926e-1bcbefbed111" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_01a01567-fccb-7f7a-83aa-a90e74a0af9e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_01a01567-fccb-7ad3-926e-1bcbefbed111" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_01a01567-fccb-7f7a-83aa-a90e74a0af9e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_01a01567-fccb-77ec-a3ed-2db15bb97f50" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_01a01567-fccb-7ad3-926e-1bcbefbed111" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_01a01567-fccb-77ec-a3ed-2db15bb97f50" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_01a01567-fccb-7525-9fbc-87fccf57bafe" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_01a01567-fccb-7ad3-926e-1bcbefbed111" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_01a01567-fccb-7525-9fbc-87fccf57bafe" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_01a01567-fccb-7219-b7a0-92f755c82092" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_01a01567-fccb-72da-95bc-f43c3d164e60" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_01a01567-fccb-753c-ae60-51400a7ae35a" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_01a01567-fccb-72da-95bc-f43c3d164e60" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_01a01567-fccb-78c1-81ef-42dfaf6cf508" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_01a01567-fccb-72da-95bc-f43c3d164e60" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_01a01567-fccb-78c1-81ef-42dfaf6cf508" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_01a01567-fccb-7795-9b8a-d4d31159cf2a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_01a01567-fccb-72da-95bc-f43c3d164e60" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_01a01567-fccb-7795-9b8a-d4d31159cf2a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_01a01567-fccb-7262-8e60-abd26373ab4c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_01a01567-fccb-72da-95bc-f43c3d164e60" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_01a01567-fccb-7262-8e60-abd26373ab4c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_01a01567-fccb-7cf4-8c88-5146d3025143" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_AggregateValueOfRestrictedStockAwardsVested_01a01567-fccb-727a-91b2-f60ab815e19b" xlink:href="wdc-20261002.xsd#wdc_AggregateValueOfRestrictedStockAwardsVested"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_01a01567-fccb-72da-95bc-f43c3d164e60" xlink:to="loc_wdc_AggregateValueOfRestrictedStockAwardsVested_01a01567-fccb-727a-91b2-f60ab815e19b" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.wdc.com/role/ShareholdersEquityandConvertiblePreferredStockReclassificationofNegativeAdditionalPaidinCapitalDetails" xlink:type="simple" xlink:href="wdc-20261002.xsd#ShareholdersEquityandConvertiblePreferredStockReclassificationofNegativeAdditionalPaidinCapitalDetails"/>
  <link:definitionLink xlink:role="http://www.wdc.com/role/ShareholdersEquityandConvertiblePreferredStockReclassificationofNegativeAdditionalPaidinCapitalDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_01a142b0-81f8-70cf-8843-990e7132dac1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_01a142b0-81f8-724b-8d02-6cb2db9ecdb1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_01a142b0-81f8-70cf-8843-990e7132dac1" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_01a142b0-81f8-724b-8d02-6cb2db9ecdb1" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReclassificationTypeAxis_01a14543-d623-7e74-9240-ccd40ff14d81" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ReclassificationTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_01a142b0-81f8-724b-8d02-6cb2db9ecdb1" xlink:to="loc_us-gaap_ReclassificationTypeAxis_01a14543-d623-7e74-9240-ccd40ff14d81" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReclassificationTypeDomain_01a14543-d623-7e74-9240-ccd40ff14d81_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ReclassificationTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ReclassificationTypeAxis_01a14543-d623-7e74-9240-ccd40ff14d81" xlink:to="loc_us-gaap_ReclassificationTypeDomain_01a14543-d623-7e74-9240-ccd40ff14d81_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReclassificationTypeDomain_01a14543-d623-7d89-9c4d-77805fa1776a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ReclassificationTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ReclassificationTypeAxis_01a14543-d623-7e74-9240-ccd40ff14d81" xlink:to="loc_us-gaap_ReclassificationTypeDomain_01a14543-d623-7d89-9c4d-77805fa1776a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReclassificationOtherMember_01a14544-6bc2-7659-a984-4ff2729c6636" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ReclassificationOtherMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationTypeDomain_01a14543-d623-7d89-9c4d-77805fa1776a" xlink:to="loc_us-gaap_ReclassificationOtherMember_01a14544-6bc2-7659-a984-4ff2729c6636" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapital_01a142b0-81f8-761d-ac91-d9f58063b123" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AdditionalPaidInCapital"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_01a142b0-81f8-70cf-8843-990e7132dac1" xlink:to="loc_us-gaap_AdditionalPaidInCapital_01a142b0-81f8-761d-ac91-d9f58063b123" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsAccumulatedDeficit_01a14544-e6c2-70a9-801f-0acc454139b1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RetainedEarningsAccumulatedDeficit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_01a142b0-81f8-70cf-8843-990e7132dac1" xlink:to="loc_us-gaap_RetainedEarningsAccumulatedDeficit_01a14544-e6c2-70a9-801f-0acc454139b1" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.wdc.com/role/ShareholdersEquityandConvertiblePreferredStockDividendstoCommonShareholdersDetails" xlink:type="simple" xlink:href="wdc-20261002.xsd#ShareholdersEquityandConvertiblePreferredStockDividendstoCommonShareholdersDetails"/>
  <link:definitionLink xlink:role="http://www.wdc.com/role/ShareholdersEquityandConvertiblePreferredStockDividendstoCommonShareholdersDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_01a01567-fccb-7c2f-9b50-14bdea17302b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_01a01567-fccb-7a05-9bf9-7caa59f6f823" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_01a01567-fccb-7c2f-9b50-14bdea17302b" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_01a01567-fccb-7a05-9bf9-7caa59f6f823" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_01a11178-2cd9-73b0-ae7e-dca1d3491602" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_01a01567-fccb-7a05-9bf9-7caa59f6f823" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_01a11178-2cd9-73b0-ae7e-dca1d3491602" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_01a11178-2cd9-73b0-ae7e-dca1d3491602_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_01a11178-2cd9-73b0-ae7e-dca1d3491602" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_01a11178-2cd9-73b0-ae7e-dca1d3491602_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_01a11178-2cd9-771e-b4ca-9240b1652923" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_01a11178-2cd9-73b0-ae7e-dca1d3491602" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_01a11178-2cd9-771e-b4ca-9240b1652923" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember_01a11178-79e5-7027-8cd8-00204aaeeb93" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_01a11178-2cd9-771e-b4ca-9240b1652923" xlink:to="loc_us-gaap_SubsequentEventMember_01a11178-79e5-7027-8cd8-00204aaeeb93" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockDividendsPerShareDeclared_01a01567-fccb-7bb9-9bba-68fc45989fa9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockDividendsPerShareDeclared"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_01a01567-fccb-7c2f-9b50-14bdea17302b" xlink:to="loc_us-gaap_CommonStockDividendsPerShareDeclared_01a01567-fccb-7bb9-9bba-68fc45989fa9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsOfOrdinaryDividends_01a01567-fccb-7305-bacd-097fa05c8712" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PaymentsOfOrdinaryDividends"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_01a01567-fccb-7c2f-9b50-14bdea17302b" xlink:to="loc_us-gaap_PaymentsOfOrdinaryDividends_01a01567-fccb-7305-bacd-097fa05c8712" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.wdc.com/role/ShareholdersEquityandConvertiblePreferredStockConvertiblePreferredStockDetails" xlink:type="simple" xlink:href="wdc-20261002.xsd#ShareholdersEquityandConvertiblePreferredStockConvertiblePreferredStockDetails"/>
  <link:definitionLink xlink:role="http://www.wdc.com/role/ShareholdersEquityandConvertiblePreferredStockConvertiblePreferredStockDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_01a01567-fccb-79a2-ab8f-27266343bc4f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_01a01567-fccb-71ac-ac70-0f01ec9d52b5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_01a01567-fccb-79a2-ab8f-27266343bc4f" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_01a01567-fccb-71ac-ac70-0f01ec9d52b5" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_01a01567-fccb-715c-9733-ac251d4b747a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_01a01567-fccb-71ac-ac70-0f01ec9d52b5" xlink:to="loc_us-gaap_StatementClassOfStockAxis_01a01567-fccb-715c-9733-ac251d4b747a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_01a01567-fccb-715c-9733-ac251d4b747a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_01a01567-fccb-715c-9733-ac251d4b747a" xlink:to="loc_us-gaap_ClassOfStockDomain_01a01567-fccb-715c-9733-ac251d4b747a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_01a01567-fccb-7403-856e-0cc55504e922" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_01a01567-fccb-715c-9733-ac251d4b747a" xlink:to="loc_us-gaap_ClassOfStockDomain_01a01567-fccb-7403-856e-0cc55504e922" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeriesAPreferredStockMember_01a01567-fccb-7510-a847-81e315e2e84e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SeriesAPreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_01a01567-fccb-7403-856e-0cc55504e922" xlink:to="loc_us-gaap_SeriesAPreferredStockMember_01a01567-fccb-7510-a847-81e315e2e84e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConvertiblePreferredStockMember_01a01567-fccb-7e17-82d6-431a467269b9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConvertiblePreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_01a01567-fccb-7403-856e-0cc55504e922" xlink:to="loc_us-gaap_ConvertiblePreferredStockMember_01a01567-fccb-7e17-82d6-431a467269b9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsidiarySaleOfStockAxis_01a01567-fccb-79eb-bfd9-4663f00d3fcf" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsidiarySaleOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_01a01567-fccb-71ac-ac70-0f01ec9d52b5" xlink:to="loc_us-gaap_SubsidiarySaleOfStockAxis_01a01567-fccb-79eb-bfd9-4663f00d3fcf" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SaleOfStockNameOfTransactionDomain_01a01567-fccb-79eb-bfd9-4663f00d3fcf_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SaleOfStockNameOfTransactionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsidiarySaleOfStockAxis_01a01567-fccb-79eb-bfd9-4663f00d3fcf" xlink:to="loc_us-gaap_SaleOfStockNameOfTransactionDomain_01a01567-fccb-79eb-bfd9-4663f00d3fcf_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SaleOfStockNameOfTransactionDomain_01a01567-fccb-773b-a883-85c104a4fa79" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SaleOfStockNameOfTransactionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsidiarySaleOfStockAxis_01a01567-fccb-79eb-bfd9-4663f00d3fcf" xlink:to="loc_us-gaap_SaleOfStockNameOfTransactionDomain_01a01567-fccb-773b-a883-85c104a4fa79" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PrivatePlacementMember_01a01567-fccb-7d6c-ab0e-4fc74b5f07d7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PrivatePlacementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SaleOfStockNameOfTransactionDomain_01a01567-fccb-773b-a883-85c104a4fa79" xlink:to="loc_us-gaap_PrivatePlacementMember_01a01567-fccb-7d6c-ab0e-4fc74b5f07d7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_01a14271-6a32-7559-af77-4f9bbb9ed80b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_01a01567-fccb-71ac-ac70-0f01ec9d52b5" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_01a14271-6a32-7559-af77-4f9bbb9ed80b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_01a14271-6a32-7559-af77-4f9bbb9ed80b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_01a14271-6a32-7559-af77-4f9bbb9ed80b" xlink:to="loc_us-gaap_EquityComponentDomain_01a14271-6a32-7559-af77-4f9bbb9ed80b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_01a14271-6a32-763b-b953-aae08d4adefc" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_01a14271-6a32-7559-af77-4f9bbb9ed80b" xlink:to="loc_us-gaap_EquityComponentDomain_01a14271-6a32-763b-b953-aae08d4adefc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_SeriesAConvertiblePreferredStockDueToParticipationRightsMember_01a14271-6a32-7cd8-87a9-e7ab866d36c7" xlink:href="wdc-20261002.xsd#wdc_SeriesAConvertiblePreferredStockDueToParticipationRightsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_01a14271-6a32-763b-b953-aae08d4adefc" xlink:to="loc_wdc_SeriesAConvertiblePreferredStockDueToParticipationRightsMember_01a14271-6a32-7cd8-87a9-e7ab866d36c7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TemporaryEquityParOrStatedValuePerShare_01a0adb5-cce7-7af8-84da-f6aadd56a05e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TemporaryEquityParOrStatedValuePerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_01a01567-fccb-79a2-ab8f-27266343bc4f" xlink:to="loc_us-gaap_TemporaryEquityParOrStatedValuePerShare_01a0adb5-cce7-7af8-84da-f6aadd56a05e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_TemporaryEquityPreferredStockDividendRatePercentage_01a01567-fccb-74c9-b162-98dd807c50d5" xlink:href="wdc-20261002.xsd#wdc_TemporaryEquityPreferredStockDividendRatePercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_01a01567-fccb-79a2-ab8f-27266343bc4f" xlink:to="loc_wdc_TemporaryEquityPreferredStockDividendRatePercentage_01a01567-fccb-74c9-b162-98dd807c50d5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendsPreferredStockCash_01a01567-fccb-7af1-9099-af3e0e964028" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DividendsPreferredStockCash"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_01a01567-fccb-79a2-ab8f-27266343bc4f" xlink:to="loc_us-gaap_DividendsPreferredStockCash_01a01567-fccb-7af1-9099-af3e0e964028" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsOfOrdinaryDividends_01a14271-6a32-7976-bf4b-f855f0c1890e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PaymentsOfOrdinaryDividends"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_01a01567-fccb-79a2-ab8f-27266343bc4f" xlink:to="loc_us-gaap_PaymentsOfOrdinaryDividends_01a14271-6a32-7976-bf4b-f855f0c1890e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockSharesOutstanding_01a01567-fccb-7676-80b1-f5e67dfd9d22" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PreferredStockSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_01a01567-fccb-79a2-ab8f-27266343bc4f" xlink:to="loc_us-gaap_PreferredStockSharesOutstanding_01a01567-fccb-7676-80b1-f5e67dfd9d22" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockLiquidationPreferenceValue_01a01567-fccb-7b23-a3b8-f08256b31e3d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PreferredStockLiquidationPreferenceValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_01a01567-fccb-79a2-ab8f-27266343bc4f" xlink:to="loc_us-gaap_PreferredStockLiquidationPreferenceValue_01a01567-fccb-7b23-a3b8-f08256b31e3d" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendsPreferredStockPaidinkind_01a01567-fccb-7f34-88eb-40fae9ec768e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DividendsPreferredStockPaidinkind"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_01a01567-fccb-79a2-ab8f-27266343bc4f" xlink:to="loc_us-gaap_DividendsPreferredStockPaidinkind_01a01567-fccb-7f34-88eb-40fae9ec768e" xlink:type="arc" order="6"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.wdc.com/role/LegalProceedingsDetails" xlink:type="simple" xlink:href="wdc-20261002.xsd#LegalProceedingsDetails"/>
  <link:definitionLink xlink:role="http://www.wdc.com/role/LegalProceedingsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesLineItems_01a01567-fccb-7bf3-b35b-732e2ff9ffd4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingenciesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesTable_01a01567-fccb-7e99-a9d0-7fe8ccf9c92a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingenciesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LossContingenciesLineItems_01a01567-fccb-7bf3-b35b-732e2ff9ffd4" xlink:to="loc_us-gaap_LossContingenciesTable_01a01567-fccb-7e99-a9d0-7fe8ccf9c92a" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseAxis_01a01567-fccb-7bea-8646-6ddb2cc35a9b" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_LitigationCaseAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_01a01567-fccb-7e99-a9d0-7fe8ccf9c92a" xlink:to="loc_srt_LitigationCaseAxis_01a01567-fccb-7bea-8646-6ddb2cc35a9b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseTypeDomain_01a01567-fccb-7bea-8646-6ddb2cc35a9b_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_LitigationCaseTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_LitigationCaseAxis_01a01567-fccb-7bea-8646-6ddb2cc35a9b" xlink:to="loc_srt_LitigationCaseTypeDomain_01a01567-fccb-7bea-8646-6ddb2cc35a9b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseTypeDomain_01a01567-fccb-70db-a2db-7909f52402fc" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_LitigationCaseTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_LitigationCaseAxis_01a01567-fccb-7bea-8646-6ddb2cc35a9b" xlink:to="loc_srt_LitigationCaseTypeDomain_01a01567-fccb-70db-a2db-7909f52402fc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_SPEXTechnologiesInc.LawsuitMember_01a01567-fccb-7a8a-b072-a7d3ae7e4e16" xlink:href="wdc-20261002.xsd#wdc_SPEXTechnologiesInc.LawsuitMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_LitigationCaseTypeDomain_01a01567-fccb-70db-a2db-7909f52402fc" xlink:to="loc_wdc_SPEXTechnologiesInc.LawsuitMember_01a01567-fccb-7a8a-b072-a7d3ae7e4e16" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationStatusAxis_01a01567-fccb-7fdc-8222-8f4832f5474f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LitigationStatusAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_01a01567-fccb-7e99-a9d0-7fe8ccf9c92a" xlink:to="loc_us-gaap_LitigationStatusAxis_01a01567-fccb-7fdc-8222-8f4832f5474f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationStatusDomain_01a01567-fccb-7fdc-8222-8f4832f5474f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LitigationStatusDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LitigationStatusAxis_01a01567-fccb-7fdc-8222-8f4832f5474f" xlink:to="loc_us-gaap_LitigationStatusDomain_01a01567-fccb-7fdc-8222-8f4832f5474f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationStatusDomain_01a01567-fccb-7afd-a1a0-8fe6ccf02e8a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LitigationStatusDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LitigationStatusAxis_01a01567-fccb-7fdc-8222-8f4832f5474f" xlink:to="loc_us-gaap_LitigationStatusDomain_01a01567-fccb-7afd-a1a0-8fe6ccf02e8a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SettledLitigationMember_01a01567-fccb-7f7a-b5ec-2736967ca724" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SettledLitigationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LitigationStatusDomain_01a01567-fccb-7afd-a1a0-8fe6ccf02e8a" xlink:to="loc_us-gaap_SettledLitigationMember_01a01567-fccb-7f7a-b5ec-2736967ca724" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyPendingClaimsNumber_01a01567-fccb-751a-b083-4f4a01cc6405" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingencyPendingClaimsNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_01a01567-fccb-7bf3-b35b-732e2ff9ffd4" xlink:to="loc_us-gaap_LossContingencyPendingClaimsNumber_01a01567-fccb-751a-b083-4f4a01cc6405" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyDamagesAwardedValue_01a01567-fccb-7a40-a39c-54b07f910148" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingencyDamagesAwardedValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_01a01567-fccb-7bf3-b35b-732e2ff9ffd4" xlink:to="loc_us-gaap_LossContingencyDamagesAwardedValue_01a01567-fccb-7a40-a39c-54b07f910148" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationSettlementInterest_01a01567-fccb-7b7f-8395-ae65574e0b0d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LitigationSettlementInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_01a01567-fccb-7bf3-b35b-732e2ff9ffd4" xlink:to="loc_us-gaap_LitigationSettlementInterest_01a01567-fccb-7b7f-8395-ae65574e0b0d" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://fasb.org/srt/role/srt-eedm/ExtensibleEnumerationLists" xlink:type="simple" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-roles-2026.xsd#eedm1"/>
  <link:definitionLink xlink:role="http://fasb.org/srt/role/srt-eedm/ExtensibleEnumerationLists" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetsAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherAssetsNoncurrent" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherAssetsNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract" xlink:to="loc_us-gaap_OtherAssetsNoncurrent" xlink:type="arc" order="101"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesCurrentAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LiabilitiesCurrentAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccruedLiabilitiesCurrent" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccruedLiabilitiesCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract" xlink:to="loc_us-gaap_AccruedLiabilitiesCurrent" xlink:type="arc" order="41"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://xbrl.sec.gov/ecd/role/IndividualsOnly" xlink:type="simple" xlink:href="https://xbrl.sec.gov/ecd/2026/ecd-2026.xsd#IndividualsOnly"/>
  <link:definitionLink xlink:role="http://xbrl.sec.gov/ecd/role/IndividualsOnly" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ecd_AllIndividualsMember" xlink:href="https://xbrl.sec.gov/ecd/2026/ecd-2026.xsd#ecd_AllIndividualsMember"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_BrianScottDavisMember_01a0b2fc-e516-7b00-9040-3c6e0cdb53fc" xlink:href="wdc-20261002.xsd#wdc_BrianScottDavisMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ecd_AllIndividualsMember" xlink:to="loc_wdc_BrianScottDavisMember_01a0b2fc-e516-7b00-9040-3c6e0cdb53fc" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_IrvingTanMember_01a01567-f9b1-712f-a518-62e34586a6e7" xlink:href="wdc-20261002.xsd#wdc_IrvingTanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ecd_AllIndividualsMember" xlink:to="loc_wdc_IrvingTanMember_01a01567-f9b1-712f-a518-62e34586a6e7" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_TuncDolucaMember_01a0b308-4a6d-7cfe-9899-97c6461566e2" xlink:href="wdc-20261002.xsd#wdc_TuncDolucaMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ecd_AllIndividualsMember" xlink:to="loc_wdc_TuncDolucaMember_01a0b308-4a6d-7cfe-9899-97c6461566e2" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://xbrl.sec.gov/ecd/role/TradingArrangementsOnly" xlink:type="simple" xlink:href="https://xbrl.sec.gov/ecd/2026/ecd-2026.xsd#TradingArrangmentsOnly"/>
  <link:definitionLink xlink:role="http://xbrl.sec.gov/ecd/role/TradingArrangementsOnly" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ecd_AllTradingArrangementsMember" xlink:href="https://xbrl.sec.gov/ecd/2026/ecd-2026.xsd#ecd_AllTradingArrangementsMember"/>
    <link:loc xlink:type="locator" xlink:label="loc_wdc_Mr.TansTradingArrangementSoldPriorToThePlanAmendmentMember_01a0d71e-e4c7-7979-a946-7e90b86e3d6e" xlink:href="wdc-20261002.xsd#wdc_Mr.TansTradingArrangementSoldPriorToThePlanAmendmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ecd_AllTradingArrangementsMember" xlink:to="loc_wdc_Mr.TansTradingArrangementSoldPriorToThePlanAmendmentMember_01a0d71e-e4c7-7979-a946-7e90b86e3d6e" xlink:type="arc" order="1"/>
  </link:definitionLink>
</link:linkbase>
