<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2016-09-27</periodOfReport>

    <notSubjectToSection16>1</notSubjectToSection16>

    <issuer>
        <issuerCik>0001527705</issuerCik>
        <issuerName>ALST Casino Holdco, LLC</issuerName>
        <issuerTradingSymbol>N/A</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001542591</rptOwnerCik>
            <rptOwnerName>North LV HoldCo, LLC</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>767 FIFTH AVENUE</rptOwnerStreet1>
            <rptOwnerStreet2>12TH FLOOR</rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10153</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>See Remarks</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001542590</rptOwnerCik>
            <rptOwnerName>Standard General Gaming, LLC</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>767 FIFTH AVENUE</rptOwnerStreet1>
            <rptOwnerStreet2>12TH FLOOR</rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10153</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>See Footnote 3</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001418202</rptOwnerCik>
            <rptOwnerName>Kim Soohyung</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>767 FIFTH AVENUE</rptOwnerStreet1>
            <rptOwnerStreet2>12TH FLOOR</rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10153</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>See Footnote 3</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Units</value>
            </securityTitle>
            <transactionDate>
                <value>2016-09-27</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>D</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>136807</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>771.14</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F2"/>
                    <footnoteId id="F3"/>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">These securities were disposed of pursuant to an Agreement and Plan of Merger, dated as of April 21, 2016, by and among the Issuer, Boyd Gaming Corporation (&quot;Boyd&quot;) and a wholly-owned subsidiary of Boyd.</footnote>
        <footnote id="F2">These securities were held by North LV HoldCo, LLC (&quot;HoldCo&quot;). Standard General Gaming, LLC (&quot;Standard General Gaming&quot; and, together with HoldCo, the &quot;Reporting Entities&quot;) is the voting member of HoldCo, and Mr. Kim is managing member of Standard General Gaming.  HoldCo, Standard General Gaming and Mr. Kim are referred to herein as the &quot;Reporting Persons.&quot;</footnote>
        <footnote id="F3">In their capacities described in Footnote 2, Standard General Gaming and Mr. Kim have been deemed to beneficially own indirectly the securities reported herein. Each Reporting Person disclaims beneficial ownership of the securities reported herein except to the extent of its or his pecuniary interest therein, and the inclusion of such securities in this report shall not be deemed an admission of beneficial ownership for purposes of Section 16 of the Securities Exchange Act of 1934, as amended (&quot;Section 16&quot;), or for any other purpose.</footnote>
    </footnotes>

    <remarks>Mr. Kim is the Chief Executive Officer of the Issuer and is a member of the Board of Managers of the Issuer.  The Reporting Entities take the position that they are to be deemed directors of the Issuer for purposes of Section 16, because Mr. Kim, directly or indirectly, has the power to control the investment and voting decisions of the Reporting Entities with respect to the Issuer's securities and because Mr. Kim initially became a member of the Board of Managers of the Issuer, in part, as a result of HoldCo's right, under the Issuer's Operating Agreement, to designate a member of the Board of Managers.</remarks>

    <ownerSignature>
        <signatureName>/s/ North LV HoldCo, LLC, by Standard General Gaming, LLC, its Voting Member, by Soohyung Kim, Manager</signatureName>
        <signatureDate>2016-09-28</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Standard General Gaming, LLC, by Soohyung Kim, Manager</signatureName>
        <signatureDate>2016-09-28</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Soohyung Kim</signatureName>
        <signatureDate>2016-09-28</signatureDate>
    </ownerSignature>
</ownershipDocument>
