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

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2013-01-24</periodOfReport>

    <notSubjectToSection16>1</notSubjectToSection16>

    <issuer>
        <issuerCik>0001374993</issuerCik>
        <issuerName>NextWave Wireless Inc.</issuerName>
        <issuerTradingSymbol>WAVE.PK</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001367638</rptOwnerCik>
            <rptOwnerName>Webster William H</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O NEXTWAVE WIRELESS INC.</rptOwnerStreet1>
            <rptOwnerStreet2>12264 EL CAMINO REAL, SUITE 305</rptOwnerStreet2>
            <rptOwnerCity>SAN DIEGO</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>92130</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2013-01-24</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>D</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>15476</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Common Stock Options (right to buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>0.17</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2013-01-24</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>D</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>200000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0.83</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F2"/>
            </exerciseDate>
            <expirationDate>
                <value>2022-02-16</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>200000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">NextWave Wireless Inc. (the &quot;Issuer&quot;) was acquired (the &quot;Merger&quot;) pursuant to that certain Agreement and Plan of Merger, dated as of August 1, 2012 (the &quot;Merger Agreement&quot;), by and among the Issuer, AT&amp;T Inc. (&quot;Parent&quot;), and Rodeo Acquisition Sub Inc., a wholly owned subsidiary of Parent (&quot;Merger Sub&quot;). All shares of the Issuer's common stock, par value $0.007 per share (&quot;Common Stock&quot;), held by the Reporting Person  were exchanged for merger consideration consisting of (i) $1.00 in cash per share of Common Stock, subject to applicable withholding amounts, and (ii) one non-transferrable contingent payment right, representing a pro rata interest in an amount up to $25 million in an escrow account, which will be subject to reduction (including, to $0) in the event that indemnification claims or other amounts become payable to Parent, as described in the Merger Agreement.</footnote>
        <footnote id="F2">These options were cancelled in the Merger in exchange for a cash payment of  $166,000 in the aggregate, representing the product of (x) the excess if any, of (A) $1.00 over (B) the per share exercise price of such option ($0.17 per share) and (y) the number of shares of Common Stock for which such option has not been previously exercised.  All other stock options held by the Reporting Person were cancelled as of the Effective Time for no value.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ William H. Webster</signatureName>
        <signatureDate>2013-01-24</signatureDate>
    </ownerSignature>
</ownershipDocument>
