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

    <schemaVersion>X0609</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2026-03-24</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001780312</issuerCik>
        <issuerName>AST SpaceMobile, Inc.</issuerName>
        <issuerTradingSymbol>ASTS</issuerTradingSymbol>
        <issuerForeignTradingSymbol></issuerForeignTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001680225</rptOwnerCik>
            <rptOwnerName>Avellan Abel Antonio</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerNonUSAddressFlag>false</rptOwnerNonUSAddressFlag>
            <rptOwnerStreet1>C/O AST SPACEMOBILE, INC., MIDLAND AIR &amp;</rptOwnerStreet1>
            <rptOwnerStreet2>SPACE PORT, 2901 ENTERPRISE LANE</rptOwnerStreet2>
            <rptOwnerCity>MIDLAND</rptOwnerCity>
            <rptOwnerState>TX</rptOwnerState>
            <rptOwnerZipCode>79706</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Chief Executive Officer</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <aff10b5One>0</aff10b5One>

    <nonDerivativeTable>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Class C Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>78163078</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Class A Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2026-03-24</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>184375</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>78597453</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeHolding>
            <securityTitle>
                <value>Common Units</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F2"/>
                <footnoteId id="F3"/>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F2"/>
                <footnoteId id="F3"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F2"/>
                <footnoteId id="F3"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Class A Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>78163078</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>78163078</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Represents achievement of certain performance-based stock unit awards (&quot;PSUs&quot;) granted on December 2, 2025, following certification by the Issuer's compensation committee that the applicable individual performance conditions had been satisfied. One third of the PSUs representing 61,459 shares of Class A Common Stock will vest on March 31, 2026 and the remaining PSUs will vest equally on March 31, 2027 and March 31, 2028, subject to the Reporting Person's continued service through the vesting dates. Each PSU represents a contingent right to receive one share of the Issuer's Class A Common Stock.</footnote>
        <footnote id="F2">The securities reported in this line item represent AST Common Units. At any time on or after April 6, 2022, these AST Common Units may be redeemed by the Reporting Person in exchange for shares of Class A common stock of the Issuer on a one-to-one basis. When a holder of Class C common stock of the Issuer exchanges AST Common Units for shares of Class A common stock of the Issuer, a number of shares of Class C common stock of the Issuer equal to the number of such AST Common Units will be immediately retired by the Issuer and will no longer be outstanding. The AST Common Units do not expire.</footnote>
        <footnote id="F3">In connection with the closing of the business combination between New Providence Acquisition Corp. and AST &amp; Science, LLC (&quot;AST&quot;) on April 6, 2021, each existing common unit previously issued by AST was reclassified and reissued by AST into new Common Units on a 1-to-14.50149869 basis. In addition, each equityholder of Common Units received an equivalent number of Class B Common Stock or Class C Common Stock of the Issuer, as applicable.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Abel Avellan</signatureName>
        <signatureDate>2026-03-26</signatureDate>
    </ownerSignature>
</ownershipDocument>
