<?xml version="1.0" encoding="US-ASCII"?>
<!--XBRL Document Created with Wdesk from Workiva-->
<!-- -->
<link:linkbase xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd" xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
  <link:roleRef roleURI="http://www.viacbs.com/role/CoverPage" xlink:href="viac-20200701.xsd#CoverPage" xlink:type="simple" />
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/all" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all" xlink:type="simple" />
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default" xlink:type="simple" />
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain" xlink:type="simple" />
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member" xlink:type="simple" />
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension" xlink:type="simple" />
  <link:definitionLink xlink:role="http://www.viacbs.com/role/CoverPage" xlink:type="extended">
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_DocumentInformationLineItems" xlink:label="loc_dei_DocumentInformationLineItems_E4242F62A0745185B36610D89B21F748" xlink:type="locator" />
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_DocumentInformationTable" xlink:label="loc_dei_DocumentInformationTable_1158CA134C375CCFAC1ECFD20C0237FA" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_dei_DocumentInformationLineItems_E4242F62A0745185B36610D89B21F748" xlink:to="loc_dei_DocumentInformationTable_1158CA134C375CCFAC1ECFD20C0237FA" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementClassOfStockAxis" xlink:label="loc_us-gaap_StatementClassOfStockAxis_33D327D61E9750C29D896272BF5C43A0" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_dei_DocumentInformationTable_1158CA134C375CCFAC1ECFD20C0237FA" xlink:to="loc_us-gaap_StatementClassOfStockAxis_33D327D61E9750C29D896272BF5C43A0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_D4EC472F86050479670028F3A0B718AE_417099FBFBC65B66AE4F1065F6F0B08B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_33D327D61E9750C29D896272BF5C43A0" xlink:to="loc_us-gaap_ClassOfStockDomain_D4EC472F86050479670028F3A0B718AE_417099FBFBC65B66AE4F1065F6F0B08B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_570B0DBAD6845FCC9C08999DE86C1DFA" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_33D327D61E9750C29D896272BF5C43A0" xlink:to="loc_us-gaap_ClassOfStockDomain_570B0DBAD6845FCC9C08999DE86C1DFA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CommonClassAMember" xlink:label="loc_us-gaap_CommonClassAMember_D38B8DE8A4C45C819E47189234A70FCD" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_570B0DBAD6845FCC9C08999DE86C1DFA" xlink:to="loc_us-gaap_CommonClassAMember_D38B8DE8A4C45C819E47189234A70FCD" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CommonClassBMember" xlink:label="loc_us-gaap_CommonClassBMember_56499DDE2B885F1EB7903AEF9BA5B21D" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_570B0DBAD6845FCC9C08999DE86C1DFA" xlink:to="loc_us-gaap_CommonClassBMember_56499DDE2B885F1EB7903AEF9BA5B21D" xlink:type="arc" />
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_DocumentType" xlink:label="loc_dei_DocumentType_D30C03BD53B1565386A9901590A0A50F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_E4242F62A0745185B36610D89B21F748" xlink:to="loc_dei_DocumentType_D30C03BD53B1565386A9901590A0A50F" xlink:type="arc" />
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_DocumentPeriodEndDate" xlink:label="loc_dei_DocumentPeriodEndDate_F5AFC61894FF502B8D89E7471934FE56" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_E4242F62A0745185B36610D89B21F748" xlink:to="loc_dei_DocumentPeriodEndDate_F5AFC61894FF502B8D89E7471934FE56" xlink:type="arc" />
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_EntityRegistrantName" xlink:label="loc_dei_EntityRegistrantName_5D855DA496655476AD8B9508C68BF6FB" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_E4242F62A0745185B36610D89B21F748" xlink:to="loc_dei_EntityRegistrantName_5D855DA496655476AD8B9508C68BF6FB" xlink:type="arc" />
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_EntityIncorporationStateCountryCode" xlink:label="loc_dei_EntityIncorporationStateCountryCode_579CCD9A82B65EF38C6833389C0D91D9" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_E4242F62A0745185B36610D89B21F748" xlink:to="loc_dei_EntityIncorporationStateCountryCode_579CCD9A82B65EF38C6833389C0D91D9" xlink:type="arc" />
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_EntityFileNumber" xlink:label="loc_dei_EntityFileNumber_8C9FC302AD405BC3A0B5A5E8B66D60E6" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_E4242F62A0745185B36610D89B21F748" xlink:to="loc_dei_EntityFileNumber_8C9FC302AD405BC3A0B5A5E8B66D60E6" xlink:type="arc" />
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_EntityTaxIdentificationNumber" xlink:label="loc_dei_EntityTaxIdentificationNumber_8F818A0935235127AF9114CAF1DE502B" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_E4242F62A0745185B36610D89B21F748" xlink:to="loc_dei_EntityTaxIdentificationNumber_8F818A0935235127AF9114CAF1DE502B" xlink:type="arc" />
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_EntityAddressAddressLine1" xlink:label="loc_dei_EntityAddressAddressLine1_E0C5503721F95CD8AAC727434D5E8980" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_E4242F62A0745185B36610D89B21F748" xlink:to="loc_dei_EntityAddressAddressLine1_E0C5503721F95CD8AAC727434D5E8980" xlink:type="arc" />
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_EntityAddressCityOrTown" xlink:label="loc_dei_EntityAddressCityOrTown_B8A33778213D507DBF8623F17888CD18" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_E4242F62A0745185B36610D89B21F748" xlink:to="loc_dei_EntityAddressCityOrTown_B8A33778213D507DBF8623F17888CD18" xlink:type="arc" />
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_EntityAddressStateOrProvince" xlink:label="loc_dei_EntityAddressStateOrProvince_4C1711D1877F50348C390BE56B534F80" xlink:type="locator" />
    <link:definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_E4242F62A0745185B36610D89B21F748" xlink:to="loc_dei_EntityAddressStateOrProvince_4C1711D1877F50348C390BE56B534F80" xlink:type="arc" />
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_EntityAddressPostalZipCode" xlink:label="loc_dei_EntityAddressPostalZipCode_4840D541564A58ED9E7C5AA9E204E3CD" xlink:type="locator" />
    <link:definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_E4242F62A0745185B36610D89B21F748" xlink:to="loc_dei_EntityAddressPostalZipCode_4840D541564A58ED9E7C5AA9E204E3CD" xlink:type="arc" />
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_CityAreaCode" xlink:label="loc_dei_CityAreaCode_8B092FE8DCA65328952B8D2C7DD0C3D8" xlink:type="locator" />
    <link:definitionArc order="11" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_E4242F62A0745185B36610D89B21F748" xlink:to="loc_dei_CityAreaCode_8B092FE8DCA65328952B8D2C7DD0C3D8" xlink:type="arc" />
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_LocalPhoneNumber" xlink:label="loc_dei_LocalPhoneNumber_C1D3535F749A5B98AF7132536A9CADC9" xlink:type="locator" />
    <link:definitionArc order="12" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_E4242F62A0745185B36610D89B21F748" xlink:to="loc_dei_LocalPhoneNumber_C1D3535F749A5B98AF7132536A9CADC9" xlink:type="arc" />
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_Security12bTitle" xlink:label="loc_dei_Security12bTitle_E5E05711C1FA54C8AA2896864230A6FE" xlink:type="locator" />
    <link:definitionArc order="13" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_E4242F62A0745185B36610D89B21F748" xlink:to="loc_dei_Security12bTitle_E5E05711C1FA54C8AA2896864230A6FE" xlink:type="arc" />
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_TradingSymbol" xlink:label="loc_dei_TradingSymbol_7B49973EB099570ABE73C67556AA2F2D" xlink:type="locator" />
    <link:definitionArc order="14" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_E4242F62A0745185B36610D89B21F748" xlink:to="loc_dei_TradingSymbol_7B49973EB099570ABE73C67556AA2F2D" xlink:type="arc" />
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_SecurityExchangeName" xlink:label="loc_dei_SecurityExchangeName_99E2F51B6FB451E1A6C72168C9912BD2" xlink:type="locator" />
    <link:definitionArc order="15" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_E4242F62A0745185B36610D89B21F748" xlink:to="loc_dei_SecurityExchangeName_99E2F51B6FB451E1A6C72168C9912BD2" xlink:type="arc" />
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_WrittenCommunications" xlink:label="loc_dei_WrittenCommunications_0D4DFC1B0F7058F092E889CB673626F7" xlink:type="locator" />
    <link:definitionArc order="16" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_E4242F62A0745185B36610D89B21F748" xlink:to="loc_dei_WrittenCommunications_0D4DFC1B0F7058F092E889CB673626F7" xlink:type="arc" />
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_SolicitingMaterial" xlink:label="loc_dei_SolicitingMaterial_C47FC046E65A5CF6A61C24EAFC3A28C1" xlink:type="locator" />
    <link:definitionArc order="17" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_E4242F62A0745185B36610D89B21F748" xlink:to="loc_dei_SolicitingMaterial_C47FC046E65A5CF6A61C24EAFC3A28C1" xlink:type="arc" />
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_PreCommencementTenderOffer" xlink:label="loc_dei_PreCommencementTenderOffer_B04BC8F928F25BE19E405C61DC7F50D8" xlink:type="locator" />
    <link:definitionArc order="18" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_E4242F62A0745185B36610D89B21F748" xlink:to="loc_dei_PreCommencementTenderOffer_B04BC8F928F25BE19E405C61DC7F50D8" xlink:type="arc" />
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_PreCommencementIssuerTenderOffer" xlink:label="loc_dei_PreCommencementIssuerTenderOffer_F52C37575CB75B38B4381C8B5D8CEC7A" xlink:type="locator" />
    <link:definitionArc order="19" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_E4242F62A0745185B36610D89B21F748" xlink:to="loc_dei_PreCommencementIssuerTenderOffer_F52C37575CB75B38B4381C8B5D8CEC7A" xlink:type="arc" />
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_EntityEmergingGrowthCompany" xlink:label="loc_dei_EntityEmergingGrowthCompany_50BBE408AB945624BC11E5316910163E" xlink:type="locator" />
    <link:definitionArc order="20" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_E4242F62A0745185B36610D89B21F748" xlink:to="loc_dei_EntityEmergingGrowthCompany_50BBE408AB945624BC11E5316910163E" xlink:type="arc" />
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_EntityCentralIndexKey" xlink:label="loc_dei_EntityCentralIndexKey_30290EFEFBC75F1396607AB1634E2FCB" xlink:type="locator" />
    <link:definitionArc order="21" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_E4242F62A0745185B36610D89B21F748" xlink:to="loc_dei_EntityCentralIndexKey_30290EFEFBC75F1396607AB1634E2FCB" xlink:type="arc" />
    <link:loc xlink:href="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd#dei_AmendmentFlag" xlink:label="loc_dei_AmendmentFlag_B57BE50E258D5573BF674D3C500D8825" xlink:type="locator" />
    <link:definitionArc order="22" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_E4242F62A0745185B36610D89B21F748" xlink:to="loc_dei_AmendmentFlag_B57BE50E258D5573BF674D3C500D8825" xlink:type="arc" />
  </link:definitionLink>
</link:linkbase>
