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

<!--XBRL Document Created with the Workiva Platform-->
<!--Copyright 2026 Workiva-->
<!--r:019f1e89-f988-7b2a-b01e-a2254e027107,g:44269d4a-78b9-418e-a712-4c2b3516b771-->
<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.bellring.com/role/CONDENSEDCONSOLIDATEDSTATEMENTSOFSTOCKHOLDERSDEFICITUnaudited" xlink:type="simple" xlink:href="brbr-20260630.xsd#CONDENSEDCONSOLIDATEDSTATEMENTSOFSTOCKHOLDERSDEFICITUnaudited"/>
  <link:definitionLink xlink:role="http://www.bellring.com/role/CONDENSEDCONSOLIDATEDSTATEMENTSOFSTOCKHOLDERSDEFICITUnaudited" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_019f1e89-fa2a-7faf-9a15-ec94fbf083a0" 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_019f1e89-fa2a-75c5-aca6-ead0e61227d2" 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_019f1e89-fa2a-7faf-9a15-ec94fbf083a0" xlink:to="loc_us-gaap_StatementTable_019f1e89-fa2a-75c5-aca6-ead0e61227d2" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_019f1e89-fa2a-7dd9-9dff-5d1e463bbfae" 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_019f1e89-fa2a-75c5-aca6-ead0e61227d2" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_019f1e89-fa2a-7dd9-9dff-5d1e463bbfae" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_019f1e89-fa2a-7dd9-9dff-5d1e463bbfae_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_019f1e89-fa2a-7dd9-9dff-5d1e463bbfae" xlink:to="loc_us-gaap_EquityComponentDomain_019f1e89-fa2a-7dd9-9dff-5d1e463bbfae_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_019f1e89-fa2a-7327-a989-cc32fe2f901e" 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_019f1e89-fa2a-7dd9-9dff-5d1e463bbfae" xlink:to="loc_us-gaap_EquityComponentDomain_019f1e89-fa2a-7327-a989-cc32fe2f901e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_019f1e89-fa2a-726e-be74-f85c08bf4a4e" 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_019f1e89-fa2a-7327-a989-cc32fe2f901e" xlink:to="loc_us-gaap_CommonStockMember_019f1e89-fa2a-726e-be74-f85c08bf4a4e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapitalMember_019f1e89-fa2a-7e93-9995-571f5066f155" 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_019f1e89-fa2a-7327-a989-cc32fe2f901e" xlink:to="loc_us-gaap_AdditionalPaidInCapitalMember_019f1e89-fa2a-7e93-9995-571f5066f155" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsMember_019f1e89-fa2a-72cc-b66f-8ffcd7f3b167" 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_019f1e89-fa2a-7327-a989-cc32fe2f901e" xlink:to="loc_us-gaap_RetainedEarningsMember_019f1e89-fa2a-72cc-b66f-8ffcd7f3b167" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_019f1e89-fa2a-70e5-b920-a29e033d51a8" 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_019f1e89-fa2a-7327-a989-cc32fe2f901e" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_019f1e89-fa2a-70e5-b920-a29e033d51a8" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockCommonMember_019f1e89-fa2a-7ae8-aaee-e8d5dc9357d8" 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_019f1e89-fa2a-7327-a989-cc32fe2f901e" xlink:to="loc_us-gaap_TreasuryStockCommonMember_019f1e89-fa2a-7ae8-aaee-e8d5dc9357d8" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019f1e89-fa2a-70c2-8286-4d545f2dc785" 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_019f1e89-fa2a-7faf-9a15-ec94fbf083a0" xlink:to="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019f1e89-fa2a-70c2-8286-4d545f2dc785" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_019f1e89-fa2a-7192-af4b-ddc4ec77bc6a" 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_019f1e89-fa2a-70c2-8286-4d545f2dc785" xlink:to="loc_us-gaap_StockholdersEquity_019f1e89-fa2a-7192-af4b-ddc4ec77bc6a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredCompensationArrangementWithIndividualFairValueOfSharesIssued_019f1e89-fa2a-7629-84e2-ed6020c9405c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DeferredCompensationArrangementWithIndividualFairValueOfSharesIssued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019f1e89-fa2a-70c2-8286-4d545f2dc785" xlink:to="loc_us-gaap_DeferredCompensationArrangementWithIndividualFairValueOfSharesIssued_019f1e89-fa2a-7629-84e2-ed6020c9405c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_019f1e89-fa2a-71dc-9535-e6576a82c8a0" 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_019f1e89-fa2a-70c2-8286-4d545f2dc785" xlink:to="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_019f1e89-fa2a-71dc-9535-e6576a82c8a0" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_019f1e89-fa2a-703a-8859-75adb731dc9c" 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_019f1e89-fa2a-70c2-8286-4d545f2dc785" xlink:to="loc_us-gaap_NetIncomeLoss_019f1e89-fa2a-703a-8859-75adb731dc9c" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationGainLossArisingDuringPeriodNetOfTax_019f1e89-fa2a-7edc-a4ae-dcafa6da0ab2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationGainLossArisingDuringPeriodNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019f1e89-fa2a-70c2-8286-4d545f2dc785" xlink:to="loc_us-gaap_OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationGainLossArisingDuringPeriodNetOfTax_019f1e89-fa2a-7edc-a4ae-dcafa6da0ab2" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockValueAcquiredCostMethod_019f1e89-fa2a-753c-8cc6-a92759992999" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TreasuryStockValueAcquiredCostMethod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019f1e89-fa2a-70c2-8286-4d545f2dc785" xlink:to="loc_us-gaap_TreasuryStockValueAcquiredCostMethod_019f1e89-fa2a-753c-8cc6-a92759992999" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_019f1e89-fa2a-7f67-8a5d-a24ace7985d6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockholdersEquity"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.bellring.com/role/REVENUEDetails" xlink:type="simple" xlink:href="brbr-20260630.xsd#REVENUEDetails"/>
  <link:definitionLink xlink:role="http://www.bellring.com/role/REVENUEDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueLineItems_019f1e89-fa2a-7268-a662-38b13bbdf8a0" 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_019f1e89-fa2a-7850-94d2-6930fc98b544" 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_019f1e89-fa2a-7268-a662-38b13bbdf8a0" xlink:to="loc_us-gaap_DisaggregationOfRevenueTable_019f1e89-fa2a-7850-94d2-6930fc98b544" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_019f1e89-fa2a-7e65-bb81-c8bfed709f84" 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_019f1e89-fa2a-7850-94d2-6930fc98b544" xlink:to="loc_srt_ProductOrServiceAxis_019f1e89-fa2a-7e65-bb81-c8bfed709f84" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019f1e89-fa2a-7e65-bb81-c8bfed709f84_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_019f1e89-fa2a-7e65-bb81-c8bfed709f84" xlink:to="loc_srt_ProductsAndServicesDomain_019f1e89-fa2a-7e65-bb81-c8bfed709f84_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019f1e89-fa2a-71b0-b3d3-07fbea3f9868" 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_019f1e89-fa2a-7e65-bb81-c8bfed709f84" xlink:to="loc_srt_ProductsAndServicesDomain_019f1e89-fa2a-71b0-b3d3-07fbea3f9868" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_brbr_ShakesandotherbeveragesMember_019f1e89-fa2a-74c0-a747-544142bcfbc9" xlink:href="brbr-20260630.xsd#brbr_ShakesandotherbeveragesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019f1e89-fa2a-71b0-b3d3-07fbea3f9868" xlink:to="loc_brbr_ShakesandotherbeveragesMember_019f1e89-fa2a-74c0-a747-544142bcfbc9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_brbr_PowdersMember_019f1e89-fa2a-742c-b85d-bbd48e5dad6d" xlink:href="brbr-20260630.xsd#brbr_PowdersMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019f1e89-fa2a-71b0-b3d3-07fbea3f9868" xlink:to="loc_brbr_PowdersMember_019f1e89-fa2a-742c-b85d-bbd48e5dad6d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_brbr_OtherProductsMember_019f1e89-fa2a-7624-bd36-3020ceb4a490" xlink:href="brbr-20260630.xsd#brbr_OtherProductsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019f1e89-fa2a-71b0-b3d3-07fbea3f9868" xlink:to="loc_brbr_OtherProductsMember_019f1e89-fa2a-7624-bd36-3020ceb4a490" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_019f1e89-fa2a-768d-8e82-472e5e0edcc4" 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_019f1e89-fa2a-7268-a662-38b13bbdf8a0" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_019f1e89-fa2a-768d-8e82-472e5e0edcc4" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.bellring.com/role/RELATEDPARTYTRANSACTIONSDetails" xlink:type="simple" xlink:href="brbr-20260630.xsd#RELATEDPARTYTRANSACTIONSDetails"/>
  <link:definitionLink xlink:role="http://www.bellring.com/role/RELATEDPARTYTRANSACTIONSDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionLineItems_019f1e89-fa2a-72e8-9c2c-7e7d20e8399d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyTransactionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_019f1e89-fa2a-73f0-8571-c29134200981" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_019f1e89-fa2a-72e8-9c2c-7e7d20e8399d" xlink:to="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_019f1e89-fa2a-73f0-8571-c29134200981" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_019f1e89-fa2a-7a16-bd4e-9013b51093e3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_019f1e89-fa2a-73f0-8571-c29134200981" xlink:to="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_019f1e89-fa2a-7a16-bd4e-9013b51093e3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_019f1e89-fa2a-7a16-bd4e-9013b51093e3_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_019f1e89-fa2a-7a16-bd4e-9013b51093e3" xlink:to="loc_us-gaap_RelatedPartyDomain_019f1e89-fa2a-7a16-bd4e-9013b51093e3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_019f1e89-fa2a-7ece-bc8c-e9f81d7a3837" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_019f1e89-fa2a-7a16-bd4e-9013b51093e3" xlink:to="loc_us-gaap_RelatedPartyDomain_019f1e89-fa2a-7ece-bc8c-e9f81d7a3837" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyMember_019f1e89-fa2a-70bb-bd6b-30a4d48cc2cd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyDomain_019f1e89-fa2a-7ece-bc8c-e9f81d7a3837" xlink:to="loc_us-gaap_RelatedPartyMember_019f1e89-fa2a-70bb-bd6b-30a4d48cc2cd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionAxis_019f1e89-fa2a-7039-9af9-3440ec31f0d2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyTransactionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_019f1e89-fa2a-73f0-8571-c29134200981" xlink:to="loc_us-gaap_RelatedPartyTransactionAxis_019f1e89-fa2a-7039-9af9-3440ec31f0d2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionDomain_019f1e89-fa2a-7039-9af9-3440ec31f0d2_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyTransactionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RelatedPartyTransactionAxis_019f1e89-fa2a-7039-9af9-3440ec31f0d2" xlink:to="loc_us-gaap_RelatedPartyTransactionDomain_019f1e89-fa2a-7039-9af9-3440ec31f0d2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionDomain_019f1e89-fa2a-79fc-a99f-73a001067087" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyTransactionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RelatedPartyTransactionAxis_019f1e89-fa2a-7039-9af9-3440ec31f0d2" xlink:to="loc_us-gaap_RelatedPartyTransactionDomain_019f1e89-fa2a-79fc-a99f-73a001067087" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_brbr_MasterServiceAgreementMember_019f1e89-fa2a-7191-bdc1-1e599a6338fd" xlink:href="brbr-20260630.xsd#brbr_MasterServiceAgreementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionDomain_019f1e89-fa2a-79fc-a99f-73a001067087" xlink:to="loc_brbr_MasterServiceAgreementMember_019f1e89-fa2a-7191-bdc1-1e599a6338fd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_brbr_CoPackingAgreementMember_019f1e89-fa2a-7ec2-9967-4f87dd3aabf4" xlink:href="brbr-20260630.xsd#brbr_CoPackingAgreementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionDomain_019f1e89-fa2a-79fc-a99f-73a001067087" xlink:to="loc_brbr_CoPackingAgreementMember_019f1e89-fa2a-7ec2-9967-4f87dd3aabf4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SellingGeneralAndAdministrativeExpense_019f1e89-fa2a-79bf-8e8e-6d432cacac2b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SellingGeneralAndAdministrativeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_019f1e89-fa2a-72e8-9c2c-7e7d20e8399d" xlink:to="loc_us-gaap_SellingGeneralAndAdministrativeExpense_019f1e89-fa2a-79bf-8e8e-6d432cacac2b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionAmountsOfTransaction_019f1e89-fa2a-7ef7-a013-e3fe7ea9cc45" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyTransactionAmountsOfTransaction"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_019f1e89-fa2a-72e8-9c2c-7e7d20e8399d" xlink:to="loc_us-gaap_RelatedPartyTransactionAmountsOfTransaction_019f1e89-fa2a-7ef7-a013-e3fe7ea9cc45" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsPayableCurrent_019f1e89-fa2a-7fec-8068-cd131d005bbc" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccountsPayableCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_019f1e89-fa2a-72e8-9c2c-7e7d20e8399d" xlink:to="loc_us-gaap_AccountsPayableCurrent_019f1e89-fa2a-7fec-8068-cd131d005bbc" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.bellring.com/role/EARNINGSPERSHAREScheduleofEarningsPerShareComputationDetails" xlink:type="simple" xlink:href="brbr-20260630.xsd#EARNINGSPERSHAREScheduleofEarningsPerShareComputationDetails"/>
  <link:definitionLink xlink:role="http://www.bellring.com/role/EARNINGSPERSHAREScheduleofEarningsPerShareComputationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareDilutedLineItems_019f1e89-fad3-70d6-8e7f-c783f123afd1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EarningsPerShareDilutedLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfEarningsPerShareDilutedByCommonClassTable_019f1e89-fa2a-7fb0-a4a8-8cb80d58d54b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfEarningsPerShareDilutedByCommonClassTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_EarningsPerShareDilutedLineItems_019f1e89-fad3-70d6-8e7f-c783f123afd1" xlink:to="loc_us-gaap_ScheduleOfEarningsPerShareDilutedByCommonClassTable_019f1e89-fa2a-7fb0-a4a8-8cb80d58d54b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_019f1e89-fa2a-705d-900c-f1e8b3259c30" 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_ScheduleOfEarningsPerShareDilutedByCommonClassTable_019f1e89-fa2a-7fb0-a4a8-8cb80d58d54b" xlink:to="loc_us-gaap_AwardTypeAxis_019f1e89-fa2a-705d-900c-f1e8b3259c30" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019f1e89-fa2a-705d-900c-f1e8b3259c30_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_019f1e89-fa2a-705d-900c-f1e8b3259c30" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019f1e89-fa2a-705d-900c-f1e8b3259c30_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019f1e89-fa2a-7bfc-9b97-600ea211da92" 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_019f1e89-fa2a-705d-900c-f1e8b3259c30" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019f1e89-fa2a-7bfc-9b97-600ea211da92" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_019f1e89-fad3-701d-ab33-61f38a7e7298" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EmployeeStockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019f1e89-fa2a-7bfc-9b97-600ea211da92" xlink:to="loc_us-gaap_EmployeeStockOptionMember_019f1e89-fad3-701d-ab33-61f38a7e7298" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_019f1e89-fad3-7f9d-9073-dc93f720a862" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019f1e89-fa2a-7bfc-9b97-600ea211da92" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_019f1e89-fad3-7f9d-9073-dc93f720a862" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_brbr_PerformanceBasedRestrictedStockUnitsMember_019f1e89-fad3-707c-8498-07c76e47d56c" xlink:href="brbr-20260630.xsd#brbr_PerformanceBasedRestrictedStockUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019f1e89-fa2a-7bfc-9b97-600ea211da92" xlink:to="loc_brbr_PerformanceBasedRestrictedStockUnitsMember_019f1e89-fad3-707c-8498-07c76e47d56c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_019f1e89-fad3-79e6-859c-a15c4914abf9" 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_EarningsPerShareDilutedLineItems_019f1e89-fad3-70d6-8e7f-c783f123afd1" xlink:to="loc_us-gaap_NetIncomeLoss_019f1e89-fad3-79e6-859c-a15c4914abf9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_019f1e89-fad3-7f06-aaa6-15233186ee08" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareDilutedLineItems_019f1e89-fad3-70d6-8e7f-c783f123afd1" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_019f1e89-fad3-7f06-aaa6-15233186ee08" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements_019f1e89-fad3-7c6e-87c1-4914c3220c6f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareDilutedLineItems_019f1e89-fad3-70d6-8e7f-c783f123afd1" xlink:to="loc_us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements_019f1e89-fad3-7c6e-87c1-4914c3220c6f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_019f1e89-fad3-7885-99fe-7d88a1a71b4e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareDilutedLineItems_019f1e89-fad3-70d6-8e7f-c783f123afd1" xlink:to="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_019f1e89-fad3-7885-99fe-7d88a1a71b4e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareBasic_019f1e89-fad3-7c6e-bb36-e953d0c93b69" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EarningsPerShareBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareDilutedLineItems_019f1e89-fad3-70d6-8e7f-c783f123afd1" xlink:to="loc_us-gaap_EarningsPerShareBasic_019f1e89-fad3-7c6e-bb36-e953d0c93b69" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareDiluted_019f1e89-fad3-7dc5-a582-d646f8b8ebc9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EarningsPerShareDiluted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareDilutedLineItems_019f1e89-fad3-70d6-8e7f-c783f123afd1" xlink:to="loc_us-gaap_EarningsPerShareDiluted_019f1e89-fad3-7dc5-a582-d646f8b8ebc9" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.bellring.com/role/EARNINGSPERSHAREAntidilutivesharesexcludedfromearningspershareDetails" xlink:type="simple" xlink:href="brbr-20260630.xsd#EARNINGSPERSHAREAntidilutivesharesexcludedfromearningspershareDetails"/>
  <link:definitionLink xlink:role="http://www.bellring.com/role/EARNINGSPERSHAREAntidilutivesharesexcludedfromearningspershareDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_019f1e89-fad3-74bc-a2f7-86e13a7676a0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_019f1e89-fad3-734f-894a-5510bb5f5cd6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_019f1e89-fad3-74bc-a2f7-86e13a7676a0" xlink:to="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_019f1e89-fad3-734f-894a-5510bb5f5cd6" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_019f1e89-fad3-793d-9ea2-38f8eabcd340" 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_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_019f1e89-fad3-734f-894a-5510bb5f5cd6" xlink:to="loc_us-gaap_AwardTypeAxis_019f1e89-fad3-793d-9ea2-38f8eabcd340" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019f1e89-fad3-793d-9ea2-38f8eabcd340_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_019f1e89-fad3-793d-9ea2-38f8eabcd340" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019f1e89-fad3-793d-9ea2-38f8eabcd340_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019f1e89-fad3-7c35-9f46-e37d0e42a737" 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_019f1e89-fad3-793d-9ea2-38f8eabcd340" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019f1e89-fad3-7c35-9f46-e37d0e42a737" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_019f1e89-fad3-7aed-9e15-b833c8e1a79a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019f1e89-fad3-7c35-9f46-e37d0e42a737" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_019f1e89-fad3-7aed-9e15-b833c8e1a79a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_brbr_PerformanceBasedRestrictedStockUnitsMember_019f1e89-fad3-79f9-8cb8-f21b228feced" xlink:href="brbr-20260630.xsd#brbr_PerformanceBasedRestrictedStockUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019f1e89-fad3-7c35-9f46-e37d0e42a737" xlink:to="loc_brbr_PerformanceBasedRestrictedStockUnitsMember_019f1e89-fad3-79f9-8cb8-f21b228feced" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_brbr_BRBRStockOptionMember_019f9a6d-8d5c-72d7-9a4c-7a195663f965" xlink:href="brbr-20260630.xsd#brbr_BRBRStockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019f1e89-fad3-7c35-9f46-e37d0e42a737" xlink:to="loc_brbr_BRBRStockOptionMember_019f9a6d-8d5c-72d7-9a4c-7a195663f965" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_019f1e89-fad3-780f-a79d-82fe2fc24dad" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_019f1e89-fad3-74bc-a2f7-86e13a7676a0" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_019f1e89-fad3-780f-a79d-82fe2fc24dad" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.bellring.com/role/INTANGIBLEASSETSNETDetails" xlink:type="simple" xlink:href="brbr-20260630.xsd#INTANGIBLEASSETSNETDetails"/>
  <link:definitionLink xlink:role="http://www.bellring.com/role/INTANGIBLEASSETSNETDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_019f1e89-fad3-739b-93c1-002a7ecba1eb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_019f1e89-fad3-73b2-ab26-9e95b4d5e7a3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_019f1e89-fad3-739b-93c1-002a7ecba1eb" xlink:to="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_019f1e89-fad3-73b2-ab26-9e95b4d5e7a3" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_019f1e89-fad3-7be7-a089-73b044cd2e00" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_019f1e89-fad3-73b2-ab26-9e95b4d5e7a3" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_019f1e89-fad3-7be7-a089-73b044cd2e00" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019f1e89-fad3-7be7-a089-73b044cd2e00_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_019f1e89-fad3-7be7-a089-73b044cd2e00" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019f1e89-fad3-7be7-a089-73b044cd2e00_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019f1e89-fad3-72c0-9592-fc0cb0643a05" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_019f1e89-fad3-7be7-a089-73b044cd2e00" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019f1e89-fad3-72c0-9592-fc0cb0643a05" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerRelationshipsMember_019f1e89-fad3-79df-8de2-b223367ab339" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CustomerRelationshipsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019f1e89-fad3-72c0-9592-fc0cb0643a05" xlink:to="loc_us-gaap_CustomerRelationshipsMember_019f1e89-fad3-79df-8de2-b223367ab339" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TrademarksMember_019f1e89-fad3-7bab-8fbb-1c518ed87083" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TrademarksMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019f1e89-fad3-72c0-9592-fc0cb0643a05" xlink:to="loc_us-gaap_TrademarksMember_019f1e89-fad3-7bab-8fbb-1c518ed87083" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherIntangibleAssetsMember_019f1e89-fad3-7f1a-bbe4-83cef380dde4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherIntangibleAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019f1e89-fad3-72c0-9592-fc0cb0643a05" xlink:to="loc_us-gaap_OtherIntangibleAssetsMember_019f1e89-fad3-7f1a-bbe4-83cef380dde4" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsGrossAbstract_019f1e89-fad3-7163-8a11-aedf3778840a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetsGrossAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_019f1e89-fad3-739b-93c1-002a7ecba1eb" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsGrossAbstract_019f1e89-fad3-7163-8a11-aedf3778840a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsGross_019f1e89-fad3-75c7-a9e1-d2597c821f50" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetsGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsGrossAbstract_019f1e89-fad3-7163-8a11-aedf3778840a" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsGross_019f1e89-fad3-75c7-a9e1-d2597c821f50" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_019f1e89-fad3-7a33-b6fc-b0c3328e8670" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsGrossAbstract_019f1e89-fad3-7163-8a11-aedf3778840a" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_019f1e89-fad3-7a33-b6fc-b0c3328e8670" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsNet_019f1e89-fad3-7014-a545-804848dac8b6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsGrossAbstract_019f1e89-fad3-7163-8a11-aedf3778840a" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsNet_019f1e89-fad3-7014-a545-804848dac8b6" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.bellring.com/role/DERIVATIVEFINANCIALINSTRUMENTSDerivativeInstrumentsinCondensedConsolidatedBalanceSheetsDetails" xlink:type="simple" xlink:href="brbr-20260630.xsd#DERIVATIVEFINANCIALINSTRUMENTSDerivativeInstrumentsinCondensedConsolidatedBalanceSheetsDetails"/>
  <link:definitionLink xlink:role="http://www.bellring.com/role/DERIVATIVEFINANCIALINSTRUMENTSDerivativeInstrumentsinCondensedConsolidatedBalanceSheetsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_019f1e89-fad3-7689-b3a1-5ab029ffa184" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_019f1e89-fad3-73e8-b7b8-5d5a4985e468" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_019f1e89-fad3-7689-b3a1-5ab029ffa184" xlink:to="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_019f1e89-fad3-73e8-b7b8-5d5a4985e468" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementOfFinancialPositionLocationBalanceAxis_019f1e89-fad3-75df-8949-e9ac5ee0819d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementOfFinancialPositionLocationBalanceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_019f1e89-fad3-73e8-b7b8-5d5a4985e468" xlink:to="loc_us-gaap_StatementOfFinancialPositionLocationBalanceAxis_019f1e89-fad3-75df-8949-e9ac5ee0819d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_019f1e89-fad3-7831-90a7-6a8874fecc0f" 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_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_019f1e89-fad3-73e8-b7b8-5d5a4985e468" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_019f1e89-fad3-7831-90a7-6a8874fecc0f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019f1e89-fad3-7831-90a7-6a8874fecc0f_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_019f1e89-fad3-7831-90a7-6a8874fecc0f" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019f1e89-fad3-7831-90a7-6a8874fecc0f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019f1e89-fad3-7162-894b-83c67245509f" 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_019f1e89-fad3-7831-90a7-6a8874fecc0f" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019f1e89-fad3-7162-894b-83c67245509f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommodityContractMember_019f1e89-fad3-7d89-9251-4a7b3410fd5f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommodityContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019f1e89-fad3-7162-894b-83c67245509f" xlink:to="loc_us-gaap_CommodityContractMember_019f1e89-fad3-7d89-9251-4a7b3410fd5f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssetFairValueGrossAssetIncludingNotSubjectToMasterNettingArrangement_019f1e89-fad3-74b2-ac77-81d70ffddf57" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeAssetFairValueGrossAssetIncludingNotSubjectToMasterNettingArrangement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_019f1e89-fad3-7689-b3a1-5ab029ffa184" xlink:to="loc_us-gaap_DerivativeAssetFairValueGrossAssetIncludingNotSubjectToMasterNettingArrangement_019f1e89-fad3-74b2-ac77-81d70ffddf57" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilityFairValueGrossLiabilityIncludingNotSubjectToMasterNettingArrangement_019f1e89-fad3-7530-ba25-edf029fe7915" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeLiabilityFairValueGrossLiabilityIncludingNotSubjectToMasterNettingArrangement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_019f1e89-fad3-7689-b3a1-5ab029ffa184" xlink:to="loc_us-gaap_DerivativeLiabilityFairValueGrossLiabilityIncludingNotSubjectToMasterNettingArrangement_019f1e89-fad3-7530-ba25-edf029fe7915" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.bellring.com/role/DERIVATIVEFINANCIALINSTRUMENTSDerivativeInstrumentsinCondensedConsolidatedBalanceSheetsDetails_1" xlink:type="simple" xlink:href="brbr-20260630.xsd#DERIVATIVEFINANCIALINSTRUMENTSDerivativeInstrumentsinCondensedConsolidatedBalanceSheetsDetails_1"/>
  <link:definitionLink xlink:role="http://www.bellring.com/role/DERIVATIVEFINANCIALINSTRUMENTSDerivativeInstrumentsinCondensedConsolidatedBalanceSheetsDetails_1" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_019f1e89-fad3-7689-b3a1-5ab029ffa184" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_019f1e89-fad3-73e8-b7b8-5d5a4985e468" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_019f1e89-fad3-7689-b3a1-5ab029ffa184" xlink:to="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_019f1e89-fad3-73e8-b7b8-5d5a4985e468" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_019f1e89-fad3-7831-90a7-6a8874fecc0f" 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_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_019f1e89-fad3-73e8-b7b8-5d5a4985e468" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_019f1e89-fad3-7831-90a7-6a8874fecc0f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019f1e89-fad3-7831-90a7-6a8874fecc0f_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_019f1e89-fad3-7831-90a7-6a8874fecc0f" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019f1e89-fad3-7831-90a7-6a8874fecc0f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019f1e89-fad3-7162-894b-83c67245509f" 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_019f1e89-fad3-7831-90a7-6a8874fecc0f" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019f1e89-fad3-7162-894b-83c67245509f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommodityContractMember_019f1e89-fad3-7d89-9251-4a7b3410fd5f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommodityContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019f1e89-fad3-7162-894b-83c67245509f" xlink:to="loc_us-gaap_CommodityContractMember_019f1e89-fad3-7d89-9251-4a7b3410fd5f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssetFairValueGrossAssetIncludingNotSubjectToMasterNettingArrangement_019f1e89-fad3-74b2-ac77-81d70ffddf57" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeAssetFairValueGrossAssetIncludingNotSubjectToMasterNettingArrangement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_019f1e89-fad3-7689-b3a1-5ab029ffa184" xlink:to="loc_us-gaap_DerivativeAssetFairValueGrossAssetIncludingNotSubjectToMasterNettingArrangement_019f1e89-fad3-74b2-ac77-81d70ffddf57" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilityFairValueGrossLiabilityIncludingNotSubjectToMasterNettingArrangement_019f1e89-fad3-7530-ba25-edf029fe7915" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeLiabilityFairValueGrossLiabilityIncludingNotSubjectToMasterNettingArrangement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_019f1e89-fad3-7689-b3a1-5ab029ffa184" xlink:to="loc_us-gaap_DerivativeLiabilityFairValueGrossLiabilityIncludingNotSubjectToMasterNettingArrangement_019f1e89-fad3-7530-ba25-edf029fe7915" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.bellring.com/role/FAIRVALUEMEASUREMENTSDetails" xlink:type="simple" xlink:href="brbr-20260630.xsd#FAIRVALUEMEASUREMENTSDetails"/>
  <link:definitionLink xlink:role="http://www.bellring.com/role/FAIRVALUEMEASUREMENTSDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019f1e89-fad3-7f96-8b30-16089ada6926" 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_019f1e89-fad3-7685-8d8d-6ec908ee340e" 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_019f1e89-fad3-7f96-8b30-16089ada6926" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019f1e89-fad3-7685-8d8d-6ec908ee340e" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019f1e89-fad3-73b3-92f2-3b0b0c3033a7" 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_019f1e89-fad3-7685-8d8d-6ec908ee340e" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019f1e89-fad3-73b3-92f2-3b0b0c3033a7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019f1e89-fad3-73b3-92f2-3b0b0c3033a7_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_019f1e89-fad3-73b3-92f2-3b0b0c3033a7" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019f1e89-fad3-73b3-92f2-3b0b0c3033a7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019f1e89-fad3-7a4f-bf7b-e89ec7292b47" 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_019f1e89-fad3-73b3-92f2-3b0b0c3033a7" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019f1e89-fad3-7a4f-bf7b-e89ec7292b47" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_019f1e89-fad3-7a77-a387-9ae472b69645" 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_019f1e89-fad3-7a4f-bf7b-e89ec7292b47" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_019f1e89-fad3-7a77-a387-9ae472b69645" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFairValue_019f1e89-fad3-7265-8b5f-540b47721b42" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019f1e89-fad3-7f96-8b30-16089ada6926" xlink:to="loc_us-gaap_DebtInstrumentFairValue_019f1e89-fad3-7265-8b5f-540b47721b42" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.bellring.com/role/LONGTERMDEBTScheduleofLongtermDebtDetails" xlink:type="simple" xlink:href="brbr-20260630.xsd#LONGTERMDEBTScheduleofLongtermDebtDetails"/>
  <link:definitionLink xlink:role="http://www.bellring.com/role/LONGTERMDEBTScheduleofLongtermDebtDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_019f1e89-fad3-733d-97bd-8bfa46031e1d" 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_019f1e89-fad3-786c-9e05-4ab08d829aac" 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_019f1e89-fad3-733d-97bd-8bfa46031e1d" xlink:to="loc_us-gaap_DebtInstrumentTable_019f1e89-fad3-786c-9e05-4ab08d829aac" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_019f1e89-fad3-7757-aff9-9f2c70aeff92" 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_019f1e89-fad3-786c-9e05-4ab08d829aac" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_019f1e89-fad3-7757-aff9-9f2c70aeff92" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019f1e89-fad3-7757-aff9-9f2c70aeff92_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_019f1e89-fad3-7757-aff9-9f2c70aeff92" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019f1e89-fad3-7757-aff9-9f2c70aeff92_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019f1e89-fad3-798b-be36-4545e6a07ac7" 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_019f1e89-fad3-7757-aff9-9f2c70aeff92" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019f1e89-fad3-798b-be36-4545e6a07ac7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditMember_019f1e89-fad3-74c1-85f5-8347bc9ebcc9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LineOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f1e89-fad3-798b-be36-4545e6a07ac7" xlink:to="loc_us-gaap_LineOfCreditMember_019f1e89-fad3-74c1-85f5-8347bc9ebcc9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeniorNotesMember_019f1e89-fad3-7fdf-b8aa-bb375bd12980" 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_019f1e89-fad3-798b-be36-4545e6a07ac7" xlink:to="loc_us-gaap_SeniorNotesMember_019f1e89-fad3-7fdf-b8aa-bb375bd12980" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_019f1e89-fad3-76d3-be9f-165260e898a7" 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_019f1e89-fad3-786c-9e05-4ab08d829aac" xlink:to="loc_us-gaap_DebtInstrumentAxis_019f1e89-fad3-76d3-be9f-165260e898a7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019f1e89-fad3-76d3-be9f-165260e898a7_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_019f1e89-fad3-76d3-be9f-165260e898a7" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019f1e89-fad3-76d3-be9f-165260e898a7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019f1e89-fad3-7d8d-96ea-42b77d938dd1" 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_019f1e89-fad3-76d3-be9f-165260e898a7" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019f1e89-fad3-7d8d-96ea-42b77d938dd1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_brbr_A7.00SeniorNotesMaturingInMarch2030Member_019f1e89-fad3-7a79-8c87-b0f7f61da1fd" xlink:href="brbr-20260630.xsd#brbr_A7.00SeniorNotesMaturingInMarch2030Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019f1e89-fad3-7d8d-96ea-42b77d938dd1" xlink:to="loc_brbr_A7.00SeniorNotesMaturingInMarch2030Member_019f1e89-fad3-7a79-8c87-b0f7f61da1fd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_brbr_AmendedCreditAgreementJPMorganChaseAdministratorMember_019f1e89-fad3-7fde-b2e8-8e4c36eea373" xlink:href="brbr-20260630.xsd#brbr_AmendedCreditAgreementJPMorganChaseAdministratorMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019f1e89-fad3-7d8d-96ea-42b77d938dd1" xlink:to="loc_brbr_AmendedCreditAgreementJPMorganChaseAdministratorMember_019f1e89-fad3-7fde-b2e8-8e4c36eea373" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_019f1e89-fad3-728d-9612-2e65d64d8e45" 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_019f1e89-fad3-786c-9e05-4ab08d829aac" xlink:to="loc_us-gaap_CreditFacilityAxis_019f1e89-fad3-728d-9612-2e65d64d8e45" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_019f1e89-fad3-728d-9612-2e65d64d8e45_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_019f1e89-fad3-728d-9612-2e65d64d8e45" xlink:to="loc_us-gaap_CreditFacilityDomain_019f1e89-fad3-728d-9612-2e65d64d8e45_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_019f1e89-fad3-71ed-bb87-c04a233708aa" 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_019f1e89-fad3-728d-9612-2e65d64d8e45" xlink:to="loc_us-gaap_CreditFacilityDomain_019f1e89-fad3-71ed-bb87-c04a233708aa" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_019f1e89-fad3-747d-936a-7552c2bb3971" 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_019f1e89-fad3-71ed-bb87-c04a233708aa" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_019f1e89-fad3-747d-936a-7552c2bb3971" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentCarryingAmount_019f1e89-fad3-737f-b4f9-3ff25608906f" 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_019f1e89-fad3-733d-97bd-8bfa46031e1d" xlink:to="loc_us-gaap_DebtInstrumentCarryingAmount_019f1e89-fad3-737f-b4f9-3ff25608906f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnamortizedDebtIssuanceExpense_019f1e89-fad3-73e4-a122-a7a2a56e8f52" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_UnamortizedDebtIssuanceExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f1e89-fad3-733d-97bd-8bfa46031e1d" xlink:to="loc_us-gaap_UnamortizedDebtIssuanceExpense_019f1e89-fad3-73e4-a122-a7a2a56e8f52" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebt_019f1e89-fad3-736e-a7d7-818608cd43f5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongTermDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f1e89-fad3-733d-97bd-8bfa46031e1d" xlink:to="loc_us-gaap_LongTermDebt_019f1e89-fad3-736e-a7d7-818608cd43f5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_019faf56-8a4f-7b17-bccb-faed3ad41440" 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_019f1e89-fad3-733d-97bd-8bfa46031e1d" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_019faf56-8a4f-7b17-bccb-faed3ad41440" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.bellring.com/role/LONGTERMDEBTNarrativeDetails" xlink:type="simple" xlink:href="brbr-20260630.xsd#LONGTERMDEBTNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.bellring.com/role/LONGTERMDEBTNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_019f1e89-fad3-7944-babb-f773dfdfd3fc" 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_019f1e89-fad3-78fc-ba5a-0d7b6469eccf" 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_019f1e89-fad3-7944-babb-f773dfdfd3fc" xlink:to="loc_us-gaap_DebtInstrumentTable_019f1e89-fad3-78fc-ba5a-0d7b6469eccf" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_019f1e89-fad3-76b4-8961-4fc1e26c69cd" 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_019f1e89-fad3-78fc-ba5a-0d7b6469eccf" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_019f1e89-fad3-76b4-8961-4fc1e26c69cd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019f1e89-fad3-76b4-8961-4fc1e26c69cd_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_019f1e89-fad3-76b4-8961-4fc1e26c69cd" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019f1e89-fad3-76b4-8961-4fc1e26c69cd_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019f1e89-fad3-7f99-8cab-fe994045bd8b" 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_019f1e89-fad3-76b4-8961-4fc1e26c69cd" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019f1e89-fad3-7f99-8cab-fe994045bd8b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditMember_019f1e89-fad3-76ea-9646-8599b4cd7285" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LineOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f1e89-fad3-7f99-8cab-fe994045bd8b" xlink:to="loc_us-gaap_LineOfCreditMember_019f1e89-fad3-76ea-9646-8599b4cd7285" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeniorNotesMember_019f1e89-fad3-777f-a85c-b1c85d9add16" 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_019f1e89-fad3-7f99-8cab-fe994045bd8b" xlink:to="loc_us-gaap_SeniorNotesMember_019f1e89-fad3-777f-a85c-b1c85d9add16" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateAxis_019f1e89-fad3-73ef-9400-e97df420684e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_VariableRateAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019f1e89-fad3-78fc-ba5a-0d7b6469eccf" xlink:to="loc_us-gaap_VariableRateAxis_019f1e89-fad3-73ef-9400-e97df420684e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateDomain_019f1e89-fad3-73ef-9400-e97df420684e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_VariableRateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_VariableRateAxis_019f1e89-fad3-73ef-9400-e97df420684e" xlink:to="loc_us-gaap_VariableRateDomain_019f1e89-fad3-73ef-9400-e97df420684e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateDomain_019f1e89-fad3-72d7-95d7-c7fbaadd69ff" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_VariableRateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_VariableRateAxis_019f1e89-fad3-73ef-9400-e97df420684e" xlink:to="loc_us-gaap_VariableRateDomain_019f1e89-fad3-72d7-95d7-c7fbaadd69ff" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BaseRateMember_019f1e89-fad3-74c2-8845-dc5e4a7f8eeb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BaseRateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_019f1e89-fad3-72d7-95d7-c7fbaadd69ff" xlink:to="loc_us-gaap_BaseRateMember_019f1e89-fad3-74c2-8845-dc5e4a7f8eeb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_brbr_SOFRRateMember_019f1e89-fad3-7ab3-99cb-be32636ddfa7" xlink:href="brbr-20260630.xsd#brbr_SOFRRateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_019f1e89-fad3-72d7-95d7-c7fbaadd69ff" xlink:to="loc_brbr_SOFRRateMember_019f1e89-fad3-7ab3-99cb-be32636ddfa7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EurodollarMember_019f1e89-fad3-73ad-92ca-3884a5809bd0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EurodollarMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_019f1e89-fad3-72d7-95d7-c7fbaadd69ff" xlink:to="loc_us-gaap_EurodollarMember_019f1e89-fad3-73ad-92ca-3884a5809bd0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_brbr_BritishPoundSterlingRateMember_019f1e89-fad3-73ac-85ca-d6bc9c4bcf8f" xlink:href="brbr-20260630.xsd#brbr_BritishPoundSterlingRateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_019f1e89-fad3-72d7-95d7-c7fbaadd69ff" xlink:to="loc_brbr_BritishPoundSterlingRateMember_019f1e89-fad3-73ac-85ca-d6bc9c4bcf8f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_019f1e89-fad3-748f-8b6e-91672a7228c6" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019f1e89-fad3-78fc-ba5a-0d7b6469eccf" xlink:to="loc_srt_RangeAxis_019f1e89-fad3-748f-8b6e-91672a7228c6" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019f1e89-fad3-748f-8b6e-91672a7228c6_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_019f1e89-fad3-748f-8b6e-91672a7228c6" xlink:to="loc_srt_RangeMember_019f1e89-fad3-748f-8b6e-91672a7228c6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019f1e89-fad3-7840-a292-481d7ed688ca" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_019f1e89-fad3-748f-8b6e-91672a7228c6" xlink:to="loc_srt_RangeMember_019f1e89-fad3-7840-a292-481d7ed688ca" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_019f1e89-fad3-789a-aee8-75fbb27d4f0f" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019f1e89-fad3-7840-a292-481d7ed688ca" xlink:to="loc_srt_MinimumMember_019f1e89-fad3-789a-aee8-75fbb27d4f0f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_019f1e89-fad3-7b3e-9997-f24c4633f309" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019f1e89-fad3-7840-a292-481d7ed688ca" xlink:to="loc_srt_MaximumMember_019f1e89-fad3-7b3e-9997-f24c4633f309" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_019f1e89-fad3-7954-a014-a2d90f2ca6b6" 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_019f1e89-fad3-78fc-ba5a-0d7b6469eccf" xlink:to="loc_us-gaap_DebtInstrumentAxis_019f1e89-fad3-7954-a014-a2d90f2ca6b6" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019f1e89-fad3-7954-a014-a2d90f2ca6b6_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_019f1e89-fad3-7954-a014-a2d90f2ca6b6" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019f1e89-fad3-7954-a014-a2d90f2ca6b6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019f1e89-fad3-7481-a327-cb55e7e9f21e" 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_019f1e89-fad3-7954-a014-a2d90f2ca6b6" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019f1e89-fad3-7481-a327-cb55e7e9f21e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_brbr_CreditAgreementJPMorganChaseAdministratorMember_019f1e89-fad3-733c-b836-54f78f8cbced" xlink:href="brbr-20260630.xsd#brbr_CreditAgreementJPMorganChaseAdministratorMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019f1e89-fad3-7481-a327-cb55e7e9f21e" xlink:to="loc_brbr_CreditAgreementJPMorganChaseAdministratorMember_019f1e89-fad3-733c-b836-54f78f8cbced" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_brbr_AmendedCreditAgreementJPMorganChaseAdministratorMember_019f1e89-fad3-7121-8782-5036672f0394" xlink:href="brbr-20260630.xsd#brbr_AmendedCreditAgreementJPMorganChaseAdministratorMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019f1e89-fad3-7481-a327-cb55e7e9f21e" xlink:to="loc_brbr_AmendedCreditAgreementJPMorganChaseAdministratorMember_019f1e89-fad3-7121-8782-5036672f0394" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_brbr_A7.00SeniorNotesMaturingInMarch2030Member_019f1e89-fad3-783d-b64e-52ce3e0f722a" xlink:href="brbr-20260630.xsd#brbr_A7.00SeniorNotesMaturingInMarch2030Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019f1e89-fad3-7481-a327-cb55e7e9f21e" xlink:to="loc_brbr_A7.00SeniorNotesMaturingInMarch2030Member_019f1e89-fad3-783d-b64e-52ce3e0f722a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_019f1e89-fad3-7270-81bc-7ef5b99e8cf1" 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_019f1e89-fad3-78fc-ba5a-0d7b6469eccf" xlink:to="loc_us-gaap_CreditFacilityAxis_019f1e89-fad3-7270-81bc-7ef5b99e8cf1" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_019f1e89-fad3-7270-81bc-7ef5b99e8cf1_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_019f1e89-fad3-7270-81bc-7ef5b99e8cf1" xlink:to="loc_us-gaap_CreditFacilityDomain_019f1e89-fad3-7270-81bc-7ef5b99e8cf1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_019f1e89-fad3-7133-a88f-f6d160a652f6" 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_019f1e89-fad3-7270-81bc-7ef5b99e8cf1" xlink:to="loc_us-gaap_CreditFacilityDomain_019f1e89-fad3-7133-a88f-f6d160a652f6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_019f1e89-fad3-72a6-b55c-dd5466259fe2" 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_019f1e89-fad3-7133-a88f-f6d160a652f6" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_019f1e89-fad3-72a6-b55c-dd5466259fe2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LetterOfCreditMember_019f1e89-fad3-760c-8923-8407edbbc87e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LetterOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_019f1e89-fad3-7133-a88f-f6d160a652f6" xlink:to="loc_us-gaap_LetterOfCreditMember_019f1e89-fad3-760c-8923-8407edbbc87e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_019f1e89-fad3-7cfe-951e-31f00de7037d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f1e89-fad3-7944-babb-f773dfdfd3fc" xlink:to="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_019f1e89-fad3-7cfe-951e-31f00de7037d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_019f1e89-fad3-7985-b7fa-74416163d6a9" 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_019f1e89-fad3-7944-babb-f773dfdfd3fc" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_019f1e89-fad3-7985-b7fa-74416163d6a9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_brbr_DebtInstrumentRestrictiveCovenantNumberOfDaysAfterMaturity_019f1e89-fad3-7903-ab4a-da0626ec8b16" xlink:href="brbr-20260630.xsd#brbr_DebtInstrumentRestrictiveCovenantNumberOfDaysAfterMaturity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f1e89-fad3-7944-babb-f773dfdfd3fc" xlink:to="loc_brbr_DebtInstrumentRestrictiveCovenantNumberOfDaysAfterMaturity_019f1e89-fad3-7903-ab4a-da0626ec8b16" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_019f1e89-fad3-7bfa-b3c4-aa889cca1b79" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentBasisSpreadOnVariableRate1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f1e89-fad3-7944-babb-f773dfdfd3fc" xlink:to="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_019f1e89-fad3-7bfa-b3c4-aa889cca1b79" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage_019f1e89-fad3-7f63-8180-d6add445f79b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f1e89-fad3-7944-babb-f773dfdfd3fc" xlink:to="loc_us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage_019f1e89-fad3-7f63-8180-d6add445f79b" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromLinesOfCredit_019f1e89-fad3-7858-8f02-9d82280e5b66" 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_019f1e89-fad3-7944-babb-f773dfdfd3fc" xlink:to="loc_us-gaap_ProceedsFromLinesOfCredit_019f1e89-fad3-7858-8f02-9d82280e5b66" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RepaymentsOfLinesOfCredit_019f1e89-fad3-7b94-ad93-b5b23b658835" 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_019f1e89-fad3-7944-babb-f773dfdfd3fc" xlink:to="loc_us-gaap_RepaymentsOfLinesOfCredit_019f1e89-fad3-7b94-ad93-b5b23b658835" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity_019f1e89-fad3-72a4-b53f-86cb7894aefe" 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_019f1e89-fad3-7944-babb-f773dfdfd3fc" xlink:to="loc_us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity_019f1e89-fad3-72a4-b53f-86cb7894aefe" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LettersOfCreditOutstandingAmount_019f1e89-fad3-78f8-8a70-2be5fa891f50" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LettersOfCreditOutstandingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f1e89-fad3-7944-babb-f773dfdfd3fc" xlink:to="loc_us-gaap_LettersOfCreditOutstandingAmount_019f1e89-fad3-78f8-8a70-2be5fa891f50" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_brbr_DebtCovenantLeverageRatio_019f1e89-fad3-7e1d-bce5-c7e6e7dd25c9" xlink:href="brbr-20260630.xsd#brbr_DebtCovenantLeverageRatio"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f1e89-fad3-7944-babb-f773dfdfd3fc" xlink:to="loc_brbr_DebtCovenantLeverageRatio_019f1e89-fad3-7e1d-bce5-c7e6e7dd25c9" xlink:type="arc" order="9"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.bellring.com/role/COMMITMENTSANDCONTINGENCIESDetails" xlink:type="simple" xlink:href="brbr-20260630.xsd#COMMITMENTSANDCONTINGENCIESDetails"/>
  <link:definitionLink xlink:role="http://www.bellring.com/role/COMMITMENTSANDCONTINGENCIESDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesLineItems_019f1e89-fad3-74f4-b282-584c86761495" 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_019f1e89-fad3-75bc-bcf4-ae1b0d257953" 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_019f1e89-fad3-74f4-b282-584c86761495" xlink:to="loc_us-gaap_LossContingenciesTable_019f1e89-fad3-75bc-bcf4-ae1b0d257953" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementOfFinancialPositionLocationBalanceAxis_019f1e89-fad3-7231-9969-bfb8fada5282" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementOfFinancialPositionLocationBalanceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_019f1e89-fad3-75bc-bcf4-ae1b0d257953" xlink:to="loc_us-gaap_StatementOfFinancialPositionLocationBalanceAxis_019f1e89-fad3-7231-9969-bfb8fada5282" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseAxis_019f1e89-fad3-7b96-90d2-161247aff7c0" 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_019f1e89-fad3-75bc-bcf4-ae1b0d257953" xlink:to="loc_srt_LitigationCaseAxis_019f1e89-fad3-7b96-90d2-161247aff7c0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseTypeDomain_019f1e89-fad3-7b96-90d2-161247aff7c0_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_019f1e89-fad3-7b96-90d2-161247aff7c0" xlink:to="loc_srt_LitigationCaseTypeDomain_019f1e89-fad3-7b96-90d2-161247aff7c0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseTypeDomain_019f1e89-fad3-76c5-af42-ae845917d811" 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_019f1e89-fad3-7b96-90d2-161247aff7c0" xlink:to="loc_srt_LitigationCaseTypeDomain_019f1e89-fad3-76c5-af42-ae845917d811" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_brbr_NewYorkSettlementMember_019f1e89-fad3-7585-beeb-7102e754f2d5" xlink:href="brbr-20260630.xsd#brbr_NewYorkSettlementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_LitigationCaseTypeDomain_019f1e89-fad3-76c5-af42-ae845917d811" xlink:to="loc_brbr_NewYorkSettlementMember_019f1e89-fad3-7585-beeb-7102e754f2d5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_brbr_MultistateSettlementMember_019f1e89-fad3-74f8-b7a1-9e52c5d02fee" xlink:href="brbr-20260630.xsd#brbr_MultistateSettlementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_LitigationCaseTypeDomain_019f1e89-fad3-76c5-af42-ae845917d811" xlink:to="loc_brbr_MultistateSettlementMember_019f1e89-fad3-74f8-b7a1-9e52c5d02fee" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_brbr_JointJuiceLitigationMember_019f1e89-fad3-73f1-896d-091d11d6a4c2" xlink:href="brbr-20260630.xsd#brbr_JointJuiceLitigationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_LitigationCaseTypeDomain_019f1e89-fad3-76c5-af42-ae845917d811" xlink:to="loc_brbr_JointJuiceLitigationMember_019f1e89-fad3-73f1-896d-091d11d6a4c2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementOfIncomeLocationBalanceAxis_019faed8-6549-75e5-8cf3-600d962601ea" 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_LossContingenciesTable_019f1e89-fad3-75bc-bcf4-ae1b0d257953" xlink:to="loc_us-gaap_StatementOfIncomeLocationBalanceAxis_019faed8-6549-75e5-8cf3-600d962601ea" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_brbr_NumberOfClassActionComplaints_019f1e89-fad3-7dad-b84b-623fb642fc43" xlink:href="brbr-20260630.xsd#brbr_NumberOfClassActionComplaints"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019f1e89-fad3-74f4-b282-584c86761495" xlink:to="loc_brbr_NumberOfClassActionComplaints_019f1e89-fad3-7dad-b84b-623fb642fc43" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationSettlementAmountAwardedToOtherParty_019f1e89-fad3-7496-924c-06edb58a52c2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LitigationSettlementAmountAwardedToOtherParty"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019f1e89-fad3-74f4-b282-584c86761495" xlink:to="loc_us-gaap_LitigationSettlementAmountAwardedToOtherParty_019f1e89-fad3-7496-924c-06edb58a52c2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_brbr_NumberOfFederalActionsCertifiedIndividualStateClasses_019f1e89-fad3-73f8-a231-b99606f0ef67" xlink:href="brbr-20260630.xsd#brbr_NumberOfFederalActionsCertifiedIndividualStateClasses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019f1e89-fad3-74f4-b282-584c86761495" xlink:to="loc_brbr_NumberOfFederalActionsCertifiedIndividualStateClasses_019f1e89-fad3-73f8-a231-b99606f0ef67" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsForLegalSettlements_019f1e89-fad3-7543-bc8b-0741c569958d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PaymentsForLegalSettlements"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019f1e89-fad3-74f4-b282-584c86761495" xlink:to="loc_us-gaap_PaymentsForLegalSettlements_019f1e89-fad3-7543-bc8b-0741c569958d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationReserveCurrent_019f1e89-fad3-734a-b982-2db4ef52ec30" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LitigationReserveCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019f1e89-fad3-74f4-b282-584c86761495" xlink:to="loc_us-gaap_LitigationReserveCurrent_019f1e89-fad3-734a-b982-2db4ef52ec30" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationSettlementExpense_019faed5-cf67-790f-84e6-6704588c994c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LitigationSettlementExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019f1e89-fad3-74f4-b282-584c86761495" xlink:to="loc_us-gaap_LitigationSettlementExpense_019faed5-cf67-790f-84e6-6704588c994c" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationSettlementLoss_019faec9-a812-7ca4-be70-4b11c3a7c405" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LitigationSettlementLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019f1e89-fad3-74f4-b282-584c86761495" xlink:to="loc_us-gaap_LitigationSettlementLoss_019faec9-a812-7ca4-be70-4b11c3a7c405" xlink:type="arc" order="6"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.bellring.com/role/COMMITMENTSANDCONTINGENCIESDetails_1" xlink:type="simple" xlink:href="brbr-20260630.xsd#COMMITMENTSANDCONTINGENCIESDetails_1"/>
  <link:definitionLink xlink:role="http://www.bellring.com/role/COMMITMENTSANDCONTINGENCIESDetails_1" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesLineItems_019f1e89-fad3-74f4-b282-584c86761495" 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_019f1e89-fad3-75bc-bcf4-ae1b0d257953" 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_019f1e89-fad3-74f4-b282-584c86761495" xlink:to="loc_us-gaap_LossContingenciesTable_019f1e89-fad3-75bc-bcf4-ae1b0d257953" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseAxis_019f1e89-fad3-7b96-90d2-161247aff7c0" 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_019f1e89-fad3-75bc-bcf4-ae1b0d257953" xlink:to="loc_srt_LitigationCaseAxis_019f1e89-fad3-7b96-90d2-161247aff7c0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseTypeDomain_019f1e89-fad3-7b96-90d2-161247aff7c0_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_019f1e89-fad3-7b96-90d2-161247aff7c0" xlink:to="loc_srt_LitigationCaseTypeDomain_019f1e89-fad3-7b96-90d2-161247aff7c0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseTypeDomain_019f1e89-fad3-76c5-af42-ae845917d811" 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_019f1e89-fad3-7b96-90d2-161247aff7c0" xlink:to="loc_srt_LitigationCaseTypeDomain_019f1e89-fad3-76c5-af42-ae845917d811" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_brbr_NewYorkSettlementMember_019f1e89-fad3-7585-beeb-7102e754f2d5" xlink:href="brbr-20260630.xsd#brbr_NewYorkSettlementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_LitigationCaseTypeDomain_019f1e89-fad3-76c5-af42-ae845917d811" xlink:to="loc_brbr_NewYorkSettlementMember_019f1e89-fad3-7585-beeb-7102e754f2d5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_brbr_MultistateSettlementMember_019f1e89-fad3-74f8-b7a1-9e52c5d02fee" xlink:href="brbr-20260630.xsd#brbr_MultistateSettlementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_LitigationCaseTypeDomain_019f1e89-fad3-76c5-af42-ae845917d811" xlink:to="loc_brbr_MultistateSettlementMember_019f1e89-fad3-74f8-b7a1-9e52c5d02fee" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_brbr_JointJuiceLitigationMember_019f1e89-fad3-73f1-896d-091d11d6a4c2" xlink:href="brbr-20260630.xsd#brbr_JointJuiceLitigationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_LitigationCaseTypeDomain_019f1e89-fad3-76c5-af42-ae845917d811" xlink:to="loc_brbr_JointJuiceLitigationMember_019f1e89-fad3-73f1-896d-091d11d6a4c2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_brbr_NumberOfClassActionComplaints_019f1e89-fad3-7dad-b84b-623fb642fc43" xlink:href="brbr-20260630.xsd#brbr_NumberOfClassActionComplaints"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019f1e89-fad3-74f4-b282-584c86761495" xlink:to="loc_brbr_NumberOfClassActionComplaints_019f1e89-fad3-7dad-b84b-623fb642fc43" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationSettlementAmountAwardedToOtherParty_019f1e89-fad3-7496-924c-06edb58a52c2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LitigationSettlementAmountAwardedToOtherParty"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019f1e89-fad3-74f4-b282-584c86761495" xlink:to="loc_us-gaap_LitigationSettlementAmountAwardedToOtherParty_019f1e89-fad3-7496-924c-06edb58a52c2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_brbr_NumberOfFederalActionsCertifiedIndividualStateClasses_019f1e89-fad3-73f8-a231-b99606f0ef67" xlink:href="brbr-20260630.xsd#brbr_NumberOfFederalActionsCertifiedIndividualStateClasses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019f1e89-fad3-74f4-b282-584c86761495" xlink:to="loc_brbr_NumberOfFederalActionsCertifiedIndividualStateClasses_019f1e89-fad3-73f8-a231-b99606f0ef67" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsForLegalSettlements_019f1e89-fad3-7543-bc8b-0741c569958d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PaymentsForLegalSettlements"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019f1e89-fad3-74f4-b282-584c86761495" xlink:to="loc_us-gaap_PaymentsForLegalSettlements_019f1e89-fad3-7543-bc8b-0741c569958d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationReserveCurrent_019f1e89-fad3-734a-b982-2db4ef52ec30" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LitigationReserveCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019f1e89-fad3-74f4-b282-584c86761495" xlink:to="loc_us-gaap_LitigationReserveCurrent_019f1e89-fad3-734a-b982-2db4ef52ec30" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationSettlementExpense_019faed5-cf67-790f-84e6-6704588c994c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LitigationSettlementExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019f1e89-fad3-74f4-b282-584c86761495" xlink:to="loc_us-gaap_LitigationSettlementExpense_019faed5-cf67-790f-84e6-6704588c994c" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationSettlementLoss_019faec9-a812-7ca4-be70-4b11c3a7c405" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LitigationSettlementLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019f1e89-fad3-74f4-b282-584c86761495" xlink:to="loc_us-gaap_LitigationSettlementLoss_019faec9-a812-7ca4-be70-4b11c3a7c405" xlink:type="arc" order="6"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.bellring.com/role/COMMITMENTSANDCONTINGENCIESDetails_2" xlink:type="simple" xlink:href="brbr-20260630.xsd#COMMITMENTSANDCONTINGENCIESDetails_2"/>
  <link:definitionLink xlink:role="http://www.bellring.com/role/COMMITMENTSANDCONTINGENCIESDetails_2" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesLineItems_019f1e89-fad3-74f4-b282-584c86761495" 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_019f1e89-fad3-75bc-bcf4-ae1b0d257953" 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_019f1e89-fad3-74f4-b282-584c86761495" xlink:to="loc_us-gaap_LossContingenciesTable_019f1e89-fad3-75bc-bcf4-ae1b0d257953" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseAxis_019f1e89-fad3-7b96-90d2-161247aff7c0" 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_019f1e89-fad3-75bc-bcf4-ae1b0d257953" xlink:to="loc_srt_LitigationCaseAxis_019f1e89-fad3-7b96-90d2-161247aff7c0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseTypeDomain_019f1e89-fad3-7b96-90d2-161247aff7c0_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_019f1e89-fad3-7b96-90d2-161247aff7c0" xlink:to="loc_srt_LitigationCaseTypeDomain_019f1e89-fad3-7b96-90d2-161247aff7c0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseTypeDomain_019f1e89-fad3-76c5-af42-ae845917d811" 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_019f1e89-fad3-7b96-90d2-161247aff7c0" xlink:to="loc_srt_LitigationCaseTypeDomain_019f1e89-fad3-76c5-af42-ae845917d811" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_brbr_NewYorkSettlementMember_019f1e89-fad3-7585-beeb-7102e754f2d5" xlink:href="brbr-20260630.xsd#brbr_NewYorkSettlementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_LitigationCaseTypeDomain_019f1e89-fad3-76c5-af42-ae845917d811" xlink:to="loc_brbr_NewYorkSettlementMember_019f1e89-fad3-7585-beeb-7102e754f2d5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_brbr_MultistateSettlementMember_019f1e89-fad3-74f8-b7a1-9e52c5d02fee" xlink:href="brbr-20260630.xsd#brbr_MultistateSettlementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_LitigationCaseTypeDomain_019f1e89-fad3-76c5-af42-ae845917d811" xlink:to="loc_brbr_MultistateSettlementMember_019f1e89-fad3-74f8-b7a1-9e52c5d02fee" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_brbr_JointJuiceLitigationMember_019f1e89-fad3-73f1-896d-091d11d6a4c2" xlink:href="brbr-20260630.xsd#brbr_JointJuiceLitigationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_LitigationCaseTypeDomain_019f1e89-fad3-76c5-af42-ae845917d811" xlink:to="loc_brbr_JointJuiceLitigationMember_019f1e89-fad3-73f1-896d-091d11d6a4c2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementOfIncomeLocationBalanceAxis_019faed8-6549-75e5-8cf3-600d962601ea" 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_LossContingenciesTable_019f1e89-fad3-75bc-bcf4-ae1b0d257953" xlink:to="loc_us-gaap_StatementOfIncomeLocationBalanceAxis_019faed8-6549-75e5-8cf3-600d962601ea" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_brbr_NumberOfClassActionComplaints_019f1e89-fad3-7dad-b84b-623fb642fc43" xlink:href="brbr-20260630.xsd#brbr_NumberOfClassActionComplaints"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019f1e89-fad3-74f4-b282-584c86761495" xlink:to="loc_brbr_NumberOfClassActionComplaints_019f1e89-fad3-7dad-b84b-623fb642fc43" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationSettlementAmountAwardedToOtherParty_019f1e89-fad3-7496-924c-06edb58a52c2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LitigationSettlementAmountAwardedToOtherParty"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019f1e89-fad3-74f4-b282-584c86761495" xlink:to="loc_us-gaap_LitigationSettlementAmountAwardedToOtherParty_019f1e89-fad3-7496-924c-06edb58a52c2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_brbr_NumberOfFederalActionsCertifiedIndividualStateClasses_019f1e89-fad3-73f8-a231-b99606f0ef67" xlink:href="brbr-20260630.xsd#brbr_NumberOfFederalActionsCertifiedIndividualStateClasses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019f1e89-fad3-74f4-b282-584c86761495" xlink:to="loc_brbr_NumberOfFederalActionsCertifiedIndividualStateClasses_019f1e89-fad3-73f8-a231-b99606f0ef67" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsForLegalSettlements_019f1e89-fad3-7543-bc8b-0741c569958d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PaymentsForLegalSettlements"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019f1e89-fad3-74f4-b282-584c86761495" xlink:to="loc_us-gaap_PaymentsForLegalSettlements_019f1e89-fad3-7543-bc8b-0741c569958d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationReserveCurrent_019f1e89-fad3-734a-b982-2db4ef52ec30" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LitigationReserveCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019f1e89-fad3-74f4-b282-584c86761495" xlink:to="loc_us-gaap_LitigationReserveCurrent_019f1e89-fad3-734a-b982-2db4ef52ec30" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationSettlementExpense_019faed5-cf67-790f-84e6-6704588c994c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LitigationSettlementExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019f1e89-fad3-74f4-b282-584c86761495" xlink:to="loc_us-gaap_LitigationSettlementExpense_019faed5-cf67-790f-84e6-6704588c994c" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationSettlementLoss_019faec9-a812-7ca4-be70-4b11c3a7c405" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LitigationSettlementLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019f1e89-fad3-74f4-b282-584c86761495" xlink:to="loc_us-gaap_LitigationSettlementLoss_019faec9-a812-7ca4-be70-4b11c3a7c405" xlink:type="arc" order="6"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.bellring.com/role/COMMITMENTSANDCONTINGENCIESDetails_3" xlink:type="simple" xlink:href="brbr-20260630.xsd#COMMITMENTSANDCONTINGENCIESDetails_3"/>
  <link:definitionLink xlink:role="http://www.bellring.com/role/COMMITMENTSANDCONTINGENCIESDetails_3" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesLineItems_019f1e89-fad3-74f4-b282-584c86761495" 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_019f1e89-fad3-75bc-bcf4-ae1b0d257953" 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_019f1e89-fad3-74f4-b282-584c86761495" xlink:to="loc_us-gaap_LossContingenciesTable_019f1e89-fad3-75bc-bcf4-ae1b0d257953" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseAxis_019f1e89-fad3-7b96-90d2-161247aff7c0" 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_019f1e89-fad3-75bc-bcf4-ae1b0d257953" xlink:to="loc_srt_LitigationCaseAxis_019f1e89-fad3-7b96-90d2-161247aff7c0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseTypeDomain_019f1e89-fad3-7b96-90d2-161247aff7c0_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_019f1e89-fad3-7b96-90d2-161247aff7c0" xlink:to="loc_srt_LitigationCaseTypeDomain_019f1e89-fad3-7b96-90d2-161247aff7c0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseTypeDomain_019f1e89-fad3-76c5-af42-ae845917d811" 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_019f1e89-fad3-7b96-90d2-161247aff7c0" xlink:to="loc_srt_LitigationCaseTypeDomain_019f1e89-fad3-76c5-af42-ae845917d811" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_brbr_NewYorkSettlementMember_019f1e89-fad3-7585-beeb-7102e754f2d5" xlink:href="brbr-20260630.xsd#brbr_NewYorkSettlementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_LitigationCaseTypeDomain_019f1e89-fad3-76c5-af42-ae845917d811" xlink:to="loc_brbr_NewYorkSettlementMember_019f1e89-fad3-7585-beeb-7102e754f2d5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_brbr_MultistateSettlementMember_019f1e89-fad3-74f8-b7a1-9e52c5d02fee" xlink:href="brbr-20260630.xsd#brbr_MultistateSettlementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_LitigationCaseTypeDomain_019f1e89-fad3-76c5-af42-ae845917d811" xlink:to="loc_brbr_MultistateSettlementMember_019f1e89-fad3-74f8-b7a1-9e52c5d02fee" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_brbr_JointJuiceLitigationMember_019f1e89-fad3-73f1-896d-091d11d6a4c2" xlink:href="brbr-20260630.xsd#brbr_JointJuiceLitigationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_LitigationCaseTypeDomain_019f1e89-fad3-76c5-af42-ae845917d811" xlink:to="loc_brbr_JointJuiceLitigationMember_019f1e89-fad3-73f1-896d-091d11d6a4c2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementOfFinancialPositionLocationBalanceAxis_019f1e89-fad3-7231-9969-bfb8fada5282" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementOfFinancialPositionLocationBalanceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_019f1e89-fad3-75bc-bcf4-ae1b0d257953" xlink:to="loc_us-gaap_StatementOfFinancialPositionLocationBalanceAxis_019f1e89-fad3-7231-9969-bfb8fada5282" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_brbr_NumberOfClassActionComplaints_019f1e89-fad3-7dad-b84b-623fb642fc43" xlink:href="brbr-20260630.xsd#brbr_NumberOfClassActionComplaints"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019f1e89-fad3-74f4-b282-584c86761495" xlink:to="loc_brbr_NumberOfClassActionComplaints_019f1e89-fad3-7dad-b84b-623fb642fc43" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationSettlementAmountAwardedToOtherParty_019f1e89-fad3-7496-924c-06edb58a52c2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LitigationSettlementAmountAwardedToOtherParty"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019f1e89-fad3-74f4-b282-584c86761495" xlink:to="loc_us-gaap_LitigationSettlementAmountAwardedToOtherParty_019f1e89-fad3-7496-924c-06edb58a52c2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_brbr_NumberOfFederalActionsCertifiedIndividualStateClasses_019f1e89-fad3-73f8-a231-b99606f0ef67" xlink:href="brbr-20260630.xsd#brbr_NumberOfFederalActionsCertifiedIndividualStateClasses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019f1e89-fad3-74f4-b282-584c86761495" xlink:to="loc_brbr_NumberOfFederalActionsCertifiedIndividualStateClasses_019f1e89-fad3-73f8-a231-b99606f0ef67" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsForLegalSettlements_019f1e89-fad3-7543-bc8b-0741c569958d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PaymentsForLegalSettlements"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019f1e89-fad3-74f4-b282-584c86761495" xlink:to="loc_us-gaap_PaymentsForLegalSettlements_019f1e89-fad3-7543-bc8b-0741c569958d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationReserveCurrent_019f1e89-fad3-734a-b982-2db4ef52ec30" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LitigationReserveCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019f1e89-fad3-74f4-b282-584c86761495" xlink:to="loc_us-gaap_LitigationReserveCurrent_019f1e89-fad3-734a-b982-2db4ef52ec30" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationSettlementExpense_019faed5-cf67-790f-84e6-6704588c994c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LitigationSettlementExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019f1e89-fad3-74f4-b282-584c86761495" xlink:to="loc_us-gaap_LitigationSettlementExpense_019faed5-cf67-790f-84e6-6704588c994c" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationSettlementLoss_019faec9-a812-7ca4-be70-4b11c3a7c405" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LitigationSettlementLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019f1e89-fad3-74f4-b282-584c86761495" xlink:to="loc_us-gaap_LitigationSettlementLoss_019faec9-a812-7ca4-be70-4b11c3a7c405" xlink:type="arc" order="6"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.bellring.com/role/SEGMENTSScheduleofSegmentInformationDetails" xlink:type="simple" xlink:href="brbr-20260630.xsd#SEGMENTSScheduleofSegmentInformationDetails"/>
  <link:definitionLink xlink:role="http://www.bellring.com/role/SEGMENTSScheduleofSegmentInformationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_019f1e89-fad3-7e34-9320-4dc368aaf98c" 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_019f1e89-fad3-74b6-87d3-32bac2eae447" 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_019f1e89-fad3-7e34-9320-4dc368aaf98c" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019f1e89-fad3-74b6-87d3-32bac2eae447" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_019f1e89-fad3-70ab-a2a8-eef49ea6427b" 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_019f1e89-fad3-74b6-87d3-32bac2eae447" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_019f1e89-fad3-70ab-a2a8-eef49ea6427b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019f1e89-fad3-70ab-a2a8-eef49ea6427b_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_019f1e89-fad3-70ab-a2a8-eef49ea6427b" xlink:to="loc_us-gaap_SegmentDomain_019f1e89-fad3-70ab-a2a8-eef49ea6427b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019f1e89-fad3-7599-8331-6d81034c9ce3" 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_019f1e89-fad3-70ab-a2a8-eef49ea6427b" xlink:to="loc_us-gaap_SegmentDomain_019f1e89-fad3-7599-8331-6d81034c9ce3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_brbr_ReportableSegmentMember_019f1e89-fad3-74dd-868d-5500365d974b" xlink:href="brbr-20260630.xsd#brbr_ReportableSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019f1e89-fad3-7599-8331-6d81034c9ce3" xlink:to="loc_brbr_ReportableSegmentMember_019f1e89-fad3-74dd-868d-5500365d974b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_019f1e89-fad3-7baa-ac62-4106acd85ae6" 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_019f1e89-fad3-7e34-9320-4dc368aaf98c" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_019f1e89-fad3-7baa-ac62-4106acd85ae6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostOfRevenue_019f1e89-fad3-77ad-aed5-157be56aac6c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CostOfRevenue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019f1e89-fad3-7e34-9320-4dc368aaf98c" xlink:to="loc_us-gaap_CostOfRevenue_019f1e89-fad3-77ad-aed5-157be56aac6c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MarketingAndAdvertisingExpense_019f1e89-fad3-7138-abdb-84764c69b01d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MarketingAndAdvertisingExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019f1e89-fad3-7e34-9320-4dc368aaf98c" xlink:to="loc_us-gaap_MarketingAndAdvertisingExpense_019f1e89-fad3-7138-abdb-84764c69b01d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AmortizationOfIntangibleAssets_019f1e89-fad3-729a-a05c-a96d5b0c51b5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AmortizationOfIntangibleAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019f1e89-fad3-7e34-9320-4dc368aaf98c" xlink:to="loc_us-gaap_AmortizationOfIntangibleAssets_019f1e89-fad3-729a-a05c-a96d5b0c51b5" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingOtherItemAmount_019f1e89-fad3-7884-a036-d084a372cfcf" 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_019f1e89-fad3-7e34-9320-4dc368aaf98c" xlink:to="loc_us-gaap_SegmentReportingOtherItemAmount_019f1e89-fad3-7884-a036-d084a372cfcf" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpense_019f1e89-fad3-77a2-b0e6-1da49d5849cd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019f1e89-fad3-7e34-9320-4dc368aaf98c" xlink:to="loc_us-gaap_InterestExpense_019f1e89-fad3-77a2-b0e6-1da49d5849cd" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_019f1e89-fad3-7096-9430-5a66484a81be" 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_019f1e89-fad3-7e34-9320-4dc368aaf98c" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefit_019f1e89-fad3-7096-9430-5a66484a81be" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_019f1e89-fad3-7e9e-bcfa-dec355aa069f" 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_019f1e89-fad3-7e34-9320-4dc368aaf98c" xlink:to="loc_us-gaap_NetIncomeLoss_019f1e89-fad3-7e9e-bcfa-dec355aa069f" xlink:type="arc" order="7"/>
  </link:definitionLink>
</link:linkbase>
