NEXTLINK COMMUNICATIONS, INC.
                       OFFER TO EXCHANGE ALL OUTSTANDING
              14% SENIOR EXCHANGEABLE REDEEMABLE PREFERRED SHARES
                   ISSUED IN RELIANCE UPON AN EXEMPTION FROM
           REGISTRATION UNDER THE SECURITIES ACT OF 1933, AS AMENDED,
            FOR 14% SENIOR EXCHANGEABLE REDEEMABLE PREFERRED SHARES
 
To Securities Dealers, Commercial Banks
 Trust Companies and Other Nominees:
 
    Enclosed for your consideration is a Prospectus dated       , 1997 (as the
same may be amended or supplemented from time to time, the "Prospectus") and a
form of Letter of Transmittal (the "Letter of Transmittal") relating to the
offer (the "Exchange Offer") by NEXTLINK Communications, Inc. (the "Company") to
exchange each outstanding 14% Senior Exchangeable Redeemable Preferred Share
issued and sold in reliance upon an exemption from registration under the
Securities Act of 1933, as amended (collectively, the "Old Preferred Share"),
for one 14% Senior Exchangeable Redeemable Preferred Share (collectively, the
"New Preferred Shares").
 
    We are asking you to contact your clients for whom you hold Old Preferred
Shares registered in your name or in the name of your nominee. In addition, we
ask you to contact your clients who, to your knowledge, hold Old Preferred
Shares registered in their own name. The Company will not pay any fees or
commissions to any broker, dealer or other person in connection with the
solicitation of tenders pursuant to the Exchange Offer. You will, however, be
reimbursed by the Company for customary mailing and handling expenses incurred
by you in forwarding any of the enclosed materials to your clients. The Company
will pay all transfer taxes, if any, applicable to the tender of Old Preferred
Shares to it or its order, except as otherwise provided in the Prospectus and
the Letter of Transmittal.
 
    Enclosed are copies of the following documents:
 
        1.  The Prospectus;
 
        2.  A Letter of Transmittal for your use in connection with the tender
    of Old Preferred Shares and for the information of your clients;
 
        3.  A form of letter that may be sent to your clients for whose accounts
    you hold Old Preferred Shares registered in your name or the name of your
    nominee, with space provided for obtaining the clients' instructions with
    regard to the Exchange Offer;
 
        4.  A form of Notice of Guaranteed Delivery; and
 
        5.  Guidelines for Certification of Taxpayer Identification Number on
    Substitute Form W-9.
 
    Your prompt action is requested. The Exchange Offer will expire at 5:00
p.m., New York City Time, on       , 1997, unless extended (the "Expiration
Date"). Old Preferred Shares tendered pursuant to the Exchange Offer may be
withdrawn, subject to the procedures described in the Prospectus, at any time
prior to the Expiration Date.
 
    To tender Old Preferred Shares, certificates for Old Preferred Shares or a
Book-Entry Confirmation, a duly executed and properly completed Letter of
Transmittal or a facsimile thereof, and any other required documents, must be
received by the Exchange Agent as provided in the Prospectus and the Letter of
Transmittal.
 
    Additional copies of the enclosed material may be obtained from the Exchange
Agent, Continental Stock Transfer & Trust Company, by calling (212) 509-4000.
 
    NOTHING HEREIN OR IN THE ENCLOSED DOCUMENTS SHALL CONSTITUTE YOU OR ANY
PERSON AS AN AGENT OF THE COMPANY OR THE EXCHANGE AGENT, OR AUTHORIZE YOU OR ANY
OTHER PERSON TO MAKE ANY STATEMENTS ON BEHALF OF ANY OF THEM WITH RESPECT TO THE
EXCHANGE OFFER, EXCEPT FOR STATEMENTS EXPRESSLY MADE IN THE PROSPECTUS AND THE
LETTER OF TRANSMITTAL.