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

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2012-08-16</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

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

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001407737</rptOwnerCik>
            <rptOwnerName>Solus Alternative Asset Management LP</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>410 PARK AVENUE</rptOwnerStreet1>
            <rptOwnerStreet2>11TH FLOOR</rptOwnerStreet2>
            <rptOwnerCity>NEW YORK, NY</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10022</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001465912</rptOwnerCik>
            <rptOwnerName>Solus GP LLC</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>410 PARK AVENUE</rptOwnerStreet1>
            <rptOwnerStreet2>11TH FLOOR</rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10022</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001465911</rptOwnerCik>
            <rptOwnerName>Pucillo Christopher</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>410 PARK AVENUE</rptOwnerStreet1>
            <rptOwnerStreet2>11TH FLOOR</rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10022</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable></nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Third Lien Convertible Notes due 2013 (the &quot;Notes&quot;)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>77.35</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2012-08-16</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>J</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
                <footnoteId id="F2"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>126690336</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F1"/>
                    <footnoteId id="F2"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>2008-10-09</value>
            </exerciseDate>
            <expirationDate>
                <value>2013-02-28</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>1637884</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See footnotes</value>
                    <footnoteId id="F3"/>
                    <footnoteId id="F4"/>
                    <footnoteId id="F5"/>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Effective August 16, 2012, the Notes were amended and restated. In connection with such amendment and restatement, the Notes were split into two series to provide that certain of Nextwave Wireless, Inc.'s (the &quot;Issuer&quot;) obligations to the holders of the Notes remain with the Issuer (including an obligation in respect of the repayment of outstanding obligations of $325 million by the Issuer to such holders) and the remaining principal balance of the Notes, plus accrued and unpaid interest as of August 16, 2012, become direct obligations of a new holding company formed by the Issuer (&quot;NextWave Holdco&quot;). (Continued in footnote 2 below)</footnote>
        <footnote id="F2">(Continued from footnote 1) NextWave Holdco was formed in connection with the proposed acquisition of the Issuer by AT&amp;T Inc. by means of a merger to hold all of the Issuer's assets other than its Wireless Communication Services and Advanced Wireless Services wireless spectrum licenses and other assets related thereto. In connection with the amendment and restatement of the Notes, the Notes were amended to remove the conversion feature and are no longer convertible into shares of common stock of the Issuer. The transactions reported herein reflect the fact that the Notes held by the Funds (as defined below) are no longer convertible into common stock of the Issuer.</footnote>
        <footnote id="F3">The securities to which this Form 4 relates were held directly by funds including Sola Ltd and Solus Core Opportunities Master Fund Ltd, each of which are Cayman Islands exempt companies (collectively, the &quot;Funds&quot;).  This Form 4 shall not be construed as an admission that the Funds are the beneficial owners of any shares of common stock of Nextwave Wireless Inc. (the &quot;Issuer&quot;), and the Funds expressly disclaim any such beneficial ownership.  Solus Alternative Asset Management LP, a Delaware limited partnership (&quot;Solus&quot;), is a registered investment adviser that serves as investment adviser to the Funds, and as such has discretion over the securities held by the Funds.  Pursuant to Rule 16a-1(a)(1), Solus is not deemed to beneficially own the securities held by the Funds but has elected to file this Form 4 nevertheless.</footnote>
        <footnote id="F4">Solus GP LLC (&quot;Solus GP&quot;) is the general partner of Solus.  Solus GP does not beneficially own any such securities as the term &quot;beneficial owner&quot; is defined in Rule 16a-1(a)(2) but has elected to file this Form 4 nevertheless.</footnote>
        <footnote id="F5">Christopher Pucillo is the managing member of Solus GP.  Mr. Pucillo disclaims beneficial ownership of the securities held directly by the Funds pursuant to Rule 16a-1(a)(4), except to the extent of the indirect pecuniary interest, if any, in such securities as a result of his interest in affiliates of Solus or the Funds.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Christopher Pucillo, as Managing Member of  Solus GP LLC, the General Partner of Solus Alternative Asset Management LP</signatureName>
        <signatureDate>2012-08-21</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Christopher Pucillo, as Managing Member of Solus GP LLC</signatureName>
        <signatureDate>2012-08-21</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Christopher Pucillo</signatureName>
        <signatureDate>2012-08-21</signatureDate>
    </ownerSignature>
</ownershipDocument>
