<PAGE>

                            STOCK PURCHASE AGREEMENT
<PAGE>

                               TABLE OF CONTENTS

                                                              Page No.
                                                              --------

     1.   Purchase and Sale of Stock..............................1
          1.1  Sale and Issuance of Stock.........................1
          1.2  The Closing........................................1

     2.   Representations and Warranties of the Company...........1
          2.1  Organization and Good Standing.....................1
          2.2  Authorization......................................1
          2.3  Valid Issuance of Stock............................2
          2.4  Title to Property and Assets.......................2
          2.5  Compliance with Other Documents....................2
          2.6  Registration Statement.............................2
          2.7  Capitalization.....................................2
          2.8  Litigation.........................................2
          2.9  Intellectual Property..............................2
          2.10 Financial Statements...............................3
          2.11 Changes............................................3
          2.12 Taxes..............................................3

     3.   Representations and Warranties of the Investor..........3
          3.1  Authorization......................................3
          3.2  Investigation......................................3
          3.3  Institutional Accredited Investor..................3
          3.4  Purchase Entirely for Own Account..................3
          3.5  Restricted Securities..............................3

     4.   Conditions to the Investor's Obligation at Closing......4
          4.1  Representations and Warranties.....................4
          4.2  Securities Laws....................................4
          4.3  Authorizations.....................................4
          4.4  Initial Public Offering of Common Stock............4

     5.   Conditions to the Company's Obligations at Closing......4
          5.1  Representations and Warranties.....................4
          5.2  Securities Laws....................................4
          5.3  Authorizations.....................................4
          5.4  Initial Public Offering of Common Stock............4
          5.5  Payment of Purchase Price..........................4

     6.   Covenants of the Company and the Investor...............5
          6.1  Agreement Not Transfer.............................5
          6.2  Market Stand-Off...................................5
          6.3  Notice of Intention to Transfer....................5
          6.4  Registration of Stock..............................5
          6.5  Publicity..........................................6

     7.   Miscellaneous...........................................6
          7.1  Governing Law......................................6
          7.2  Survival; Additional Securities....................6
<PAGE>

          7.3  Successors and Assigns.............................6
          7.4  Entire Agreement...................................6
          7.5  Notices............................................6
          7.6  Amendments and Waivers.............................6
          7.7  Legal Fees.........................................7
          7.8  Expenses...........................................7
          7.9  Titles and Subtitles...............................7
          7.10 Counterparts.......................................7
          7.11 Severability.......................................7
          7.12 Confidentiality....................................7
          7.13 Termination........................................7

<PAGE>

                           STOCK PURCHASE AGREEMENT

     THIS STOCK PURCHASE AGREEMENT is entered into as of the 11th day of
February, 2000, by and between FirstWorld Communications, Inc., a Delaware
corporation (the "Company") and TPG FirstWorld I LLC, a Delaware limited
liability company (the "Investor").

     WHEREAS, the Investor has indicated a desire to purchase the number of
shares of the Company's Series B Common Stock ("Common Stock") obtained by
dividing $50,000,000 by 93% of the per share price paid by the public for the
Company's Common Stock in the Company's initial public offering (the "IPO").

     WHEREAS, the Company has indicated a desire to sell the number of shares of
the Company's Common Stock obtained by dividing $50,000,000 by 93% of the per
share price paid by the public for the Company's Common Stock in the Company's
IPO to the Investor on the terms set forth herein.

     WHEREAS, the Company and the Investor have agreed that this Agreement shall
constitute the entire understanding and agreement between the parties with
regard to the subject matter hereof.

     NOW, THEREFORE, THE PARTIES HEREBY AGREE AS FOLLOWS:

1.   Purchase and Sale of Stock.
     --------------------------

     1.1  Sale and Issuance of Stock.  Subject to the terms and conditions of
this Agreement, the Company agrees to sell to the Investor and the Investor
agrees to purchase from the Company the number of shares of the Company's Common
Stock obtained by dividing $50,000,000 by 93% of the per share price paid by the
public for the Company's Common Stock in the Company's IPO (the "Stock"), having
the rights, preferences, privileges and restrictions set forth in the
Certificate of Incorporation of the Company (the "Certificate") on file with the
Delaware Secretary of State as of the Closing (as defined below).

     1.2  The Closing.  The purchase and sale of the Stock shall be held at the
Company's offices immediately following the closing of the Company's IPO (the
"Closing").  At the Closing, the Company will deliver the Stock to the Investor
against payment of the purchase price therefor by check payable to the order of
the Company or by wire transfer.  The per share purchase price for the Stock
shall be 93% of the per share price paid by the public for the Company's Common
Stock in the IPO.

2.   Representations and Warranties of the Company.  Except as set forth on
the schedule of exceptions delivered herewith, the Company hereby represents and
warrants to the Investor that:

     2.1  Organization and Good Standing.  The Company is a corporation duly
organized, validly existing and in good standing under the laws of the State of
Delaware and has all requisite corporate power and authority to carry on its
business as now conducted. The Company is duly qualified to transact business
and is in good standing in each jurisdiction in which the failure to so qualify
would have a material adverse effect on its business or properties.

     2.2  Authorization.  All corporate action on the part of the Company, its
officers, directors and stockholders necessary for the authorization, execution
and delivery of this Agreement, the performance of all obligations of the
Company hereunder, and the authorization, issuance, sale and delivery of the
Stock has been taken or will be taken prior to the Closing, and this Agreement
constitutes a valid and legally binding obligation of the Company, enforceable
in accordance with its terms, except (i) as limited by applicable bankruptcy,
insolvency, reorganization, moratorium, and other laws of general application
<PAGE>

affecting enforcement of creditors' rights generally and (ii) as limited by laws
relating to the availability of specific performance, injunctive relief, or
other equitable remedies.

     2.3  Valid Issuance of Stock. The Stock, when issued, sold and delivered in
accordance with the terms hereof for the consideration expressed herein, will be
duly and validly issued, fully paid and nonassessable and will be free of
restrictions on transfer other than restrictions on transfer under this
Agreement and under applicable state and federal securities laws.  Subject in
part to the truth and accuracy of the Investor's representations set forth in
Section 3 of this Agreement, the offer, sale and issuance of the Stock as
contemplated by this Agreement are exempt from the registration requirements of
any applicable state and federal securities laws.

     2.4  Title to Property and Assets. The Company owns its property and assets
free and clear of all mortgages, liens, loans and encumbrances, except such
encumbrances and liens that arise in the ordinary course of business and do not
materially impair the Company's ownership or use of such property or assets.
With respect to the property and assets it leases, the Company is in compliance
with such leases, except to the extent such non-compliance would not materially
impair the Company's business or prospects and, to the best of its knowledge,
holds a valid leasehold interest free of any liens, claims or encumbrances.  The
Company is subject to the debt covenants and other terms and conditions set
forth in the Indenture dated April 13, 1998 between the Company and the Bank of
New York as Trustee (the "Indenture").

     2.5  Compliance with Other Documents. The execution and delivery of this
Agreement, consummation of the transactions contemplated hereby, and compliance
with the terms and provisions hereof will not conflict with or result in a
breach of the terms and conditions of, or constitute a default under the
Restated Certificate or Bylaws of the Company or of any contract or agreement to
which the Company is now a party, except where such conflict, breach or default
of any such contract or agreement, either individually or in the aggregate,
would not have a material adverse effect on the Company's business, financial
condition or results of operations.

     2.6  Registration Statement. The Company's registration statement on Form
S-1, as amended, (the "Registration Statement") shall not, at the time the
Registration Statement (including any amendments or supplements thereto) is
declared effective by the Securities and Exchange Commission ("SEC"), contain
any untrue statement of a material fact or omit to state any material fact
necessary in order to make the statements therein, in light of the circumstances
under which they were made, not misleading.

     2.7  Capitalization.  The Company's capitalization information contained
in the Registration Statement is complete and accurate as of the dates specified
therein.

     2.8  Litigation. Except as disclosed in the Company's Registration
Statement, to the best of the Company's knowledge, there are no actions,
proceedings or investigations pending against the Company, that, either in any
case or in the aggregate, would result in any material adverse change in the
business, financial condition, or results of operations of the Company.

     2.9  Intellectual Property. Except as disclosed in the Registration
Statement, the Company owns, possesses or can acquire on reasonable terms,
adequate trademarks, trade names and other rights to inventions, know-how,
patents, copyrights, confidential information and other intellectual property
(collectively, "Intellectual Property Rights") necessary to conduct the business
now operated by it, or presently employed by it, and has not received any notice
of infringement of or conflict with asserted rights of others with respect to
any intellectual property rights that, if determined adversely to the
<PAGE>

Company, would individually or in the aggregate have a material adverse effect
on the condition (financial or other), business, properties or results of
operations.

     2.10 Financial Statements. The financial statements included in the
Registration Statement present fairly the financial position of the Company as
of the dates shown and its results of operations and cash flows for the periods
shown, and, except as otherwise disclosed in the Registration Statement, such
financial statements have been prepared in conformity with the generally
accepted accounting principles in the United States applied on a consistent
basis.

     2.11 Changes. Except as disclosed in the Registration Statement, since the
date of the latest audited financial statements included in the Registration
Statement there has been no material adverse change, nor any development or
event involving a prospective material adverse change, in the condition
(financial or other), business, properties or results of operations of the
Company taken as a whole.

     2.12 Taxes. The Company has filed on a timely basis all tax returns and
reports (including information returns and reports) as required by law. These
returns and reports are true and correct in all material respects except to the
extent that a reserve has been reflected on the Company's financial statements
in accordance with generally accepted accounting principles. The Company has
paid all taxes and other assessments due, except those contested by it in good
faith and except to the extent that a reserve has been reflected on the
Company's financial statements in accordance with generally accepted accounting
principles. The provision for taxes of the Company as shown in the Company's
financial statements is adequate for taxes due or accrued as of the date
thereof.

3.   Representations and Warranties of the Investor. The Investor hereby
represents and warrants that:

     3.1  Authorization. This Agreement constitutes the valid and legally
binding obligation of the Investor, enforceable in accordance with its terms,
subject to laws of general application relating to bankruptcy, insolvency and
the relief of debtors and by general principles of equity.

     3.2  Investigation. The Investor acknowledges that it has had an
opportunity to discuss the business, affairs and current prospects of the
Company with the Company's chief executive officer. The Investor further
acknowledges having had access to information about the Company that it has
requested or considers necessary for purposes of purchasing the Stock. The
foregoing, however, does not limit or modify the representations and warranties
of the Company in Section 2 of this Agreement or the right of the Investors to
rely thereon.

     3.2  Institutional Accredited Investor. The Investor is a large
institutional accredited investor.  "Accredited Investor" has the meaning
ascribed to it in Regulation D as promulgated under the Securities Act of 1933,
as amended.

     3.4  Purchase Entirely for Own Account. This Agreement is made with the
Investor in reliance upon the Investor's representation to the Company, which by
the Investor's execution of this Agreement the Investor hereby confirms, that
the Stock will be acquired for investment for the Investor's own account, not as
a nominee or agent, and not with a view to the resale or distribution of any
part thereof, and that the Investor has no present intention of selling,
granting any participation in, or otherwise distributing the same.

     3.5  Restricted Securities. Investor understands that the Stock it is
purchasing are characterized as "restricted securities" under the federal
securities laws inasmuch as they are being acquired from the Company in a
transaction not involving a public offering and that under such laws and
applicable regulations such securities may be resold without registration under
the Act, only in certain
<PAGE>

limited circumstances. In this connection, Investor represents that it is
familiar with SEC Rule 144, as presently in effect, and understands the resale
limitations imposed thereby and by the Act.

4.   Conditions to the Investor's Obligation at Closing. The obligation of the
Investor to purchase the Stock at the Closing is subject to the fulfillment to
the Investor's satisfaction on or prior to the Closing of the following
conditions:

     4.1  Representations and Warranties. The representations and warranties
made by the Company in Section 2 hereof shall be true and correct when made, and
shall be true and correct as of the Closing with the same force and effect as if
they had been made on and as of such date, subject to changes contemplated by
this Agreement. The Chief Executive Officer of the Company shall deliver at the
Closing a certificate stating that the condition specified in the preceding
sentence has been fulfilled.

     4.2  Securities Laws.  The offer and sale of the Stock to the Investor
pursuant to this Agreement shall be exempt from the registration requirements of
the Securities Act of 1933, as amended (the "Act") and qualification
requirements of all applicable state securities laws.

     4.3  Authorizations. All authorizations, approvals or permits, if any, of
any governmental authority or regulatory body that are required in connection
with the lawful issuance and sale of the Stock pursuant to this Agreement shall
have been duly obtained and shall be effective on and as of the Closing.

     4.4  Initial Public Offering of Common Stock. The closing of the initial
public offering of the Company's Series B Common Stock shall have occurred.

     4.5  Condition to Close.  The purchase of the Stock shall be subject to a
condition to closing as to any portion of the shares of Stock proposed to be
sold pursuant to this Agreement (and only that portion), that the purchase by
the Investor, individually, or taken together with all other all persons or
entities acting as a group within the meaning of Section 13(d)(3) and Section
14(d)(2) of the Securities Exchange Act of 1934, as amended, (collectively, the
"Group") not cause the Group to become the Beneficial Owner (as such term is
defined in the Company's Indenture dated April 13, 1998) of more than 35% of
Voting Stock (as such term is defined in the Indenture) of the Company.

5.   Conditions to the Company's Obligations at Closing. The obligation of the
Company to sell the Stock at the Closing is subject to the fulfillment to the
Company's satisfaction on or prior to the Closing of the following conditions:

     5.1  Representations and Warranties. The representations and warranties of
the Investor contained in Section 3 hereof shall be true as of the Closing with
the same force and effect as if they had been made on and as of such date,
subject to changes contemplated by this Agreement. An authorized officer of the
Investor shall deliver at the Closing a certificate stating that the condition
specified in the preceding sentence has been fulfilled.

     5.2  Securities Laws. The offer and sale of the Stock to the Investor
pursuant to this Agreement shall be exempt from the registration requirements of
the Act qualification requirements of all applicable state securities laws.

     5.3  Authorizations. All authorizations, approvals or permits, if any, of
any governmental authority or regulatory body that are required in connection
with the lawful issuance and sale of the Stock pursuant to this Agreement shall
have been duly obtained and shall be effective on and as of the Closing,
including without limitation filings and any necessary approvals under the Hart-
Scott-Rodino Anti-Trust Improvement Act.
<PAGE>

     5.4  Initial Public Offering of Series B Common Stock. The closing of the
initial public offering of the Company's Series B Common Stock shall have
occurred.

     5.5  Payment of Purchase Price. The Investor shall have delivered to the
Company the purchase price for the Stock as set forth in Section 1.2 hereof.

     5.6  Condition to Close.  The purchase of the Stock shall be subject to a
condition to closing as to any portion of the shares of Stock proposed to be
sold pursuant to this Agreement (and only that portion), that the purchase by
the Investor, individually, or taken together with all other all persons or
entities acting as a group within the meaning of Section 13(d)(3) and Section
14(d)(2) of the Securities Exchange Act of 1934, as amended, (collectively, the
"Group") not cause the Group to become the Beneficial Owner (as such term is
defined in the Company's Indenture dated April 13, 1998) of more than 35% of
Voting Stock (as such term is defined in the Indenture) of the Company.

6.   Covenants of the Company and the Investor.

     6.1  Agreement Not to Transfer.

     (a)  Prior to one hundred eighty (180) days after the Closing, the Investor
shall not, directly or indirectly, Transfer or offer to Transfer any shares of
the Stock other than to affiliates who agree to be bound by the terms of this
Agreement, unless the Company consents to such Transfer and the transferee
agrees to be bound by this Agreement.

     (b)  In order to enforce the transfer restrictions set forth in this
Section 6, the Company may impose stop transfer instructions with respect to the
Stock until the end of the restricted period.

     (c)  As used in this Agreement, the term "Transfer" shall mean any sale,
transfer, assignment, hypothecation, encumbrance or other disposition, whether
voluntary or involuntary, of shares of the Stock. In the case of a
hypothecation, the Transfer shall be deemed to occur both at the time of the
initial pledge and at any pledgee's sale or a sale by any secured creditor or a
retention by thc secured creditor of the pledged shares of the Stock in complete
or partial satisfaction of the indebtedness for which the shares of the Stock
are security.

     6.2  Market Stand-Off.  In addition to the transfer restrictions set forth
in Section 6.1 above (which shall in no way be limited by the following), in
connection with any underwritten public offering by the Company of its equity
securities pursuant to an effective registration statement filed under the Act,
the Investor shall not Transfer or offer to Transfer any shares of the Stock
without the prior written consent of the Company and its underwriters. Such
restriction (the "Market Stand-Off') shall be in effect for such period of time
from and after the effective date of the final prospectus for the offering as
may be requested by the Company or such underwriters; provided, however, that
(i) such Market Stand-Off shall not exceed one hundred eighty (180) days, and
(ii) the Investor shall be subject to the Market Stand-Off only if the officers
and directors of the Company are also subject to similar restrictions. In order
to enforce the Market Stand-Off, the Company may impose stop-transfer
instructions with respect to the Stock until the end of the applicable stand-off
period.

     6.3  Notice of Intention to Transfer. In the event the Investor plans to
Transfer shares of the Stock in one or more transactions, the Investor shall
inform the Company of such intention to Transfer such shares fifteen (15) days
prior to such Transfer. Investor shall agree that any transfer, sale or other
disposition of the Company's Common Stock shall be through an orderly
disposition, including, at the request of the Company, through a broker-dealer
recommended by the Company.
<PAGE>

     6.4  Registration of Stock. The Company agrees that, with regard to the
Stock, the Investor shall become a party to the Amended and Restated Investors
Rights Agreement attached as Exhibit A (the "Rights Agreement") for the sole
purpose of providing the Investor with the demand, piggyback and Form S-3
registration rights described in Sections 2.2, 2.3 and 2.4 of Rights Agreement.
Solely in connection with such demand, piggyback and S-3 registration rights set
forth in Sections 2.2, 2.3 and 2.4, the Investor shall be deemed to be a "Demand
Holder" as defined in Section 1.1 of the Rights Agreement and the shares of
Series B common stock held by the Investor shall be deemed to be "Demand Shares"
and "Registrable Securities" as such terms are defined in the Rights Agreement.

     The Investor understands and agrees that (i) the Stock will be
characterized as "restricted securities" under the federal securities laws
inasmuch as it is being acquired from the Company in a transaction not involving
a public offering and that under such laws and applicable regulations such
securities may be resold without registration under the Act only in certain
limited circumstances, and (ii) each certificate representing the Stock and any
other securities issued in respect of the Stock upon any stock split, stock
dividend, recapitalization, merger or similar event (unless no longer required
in the opinion of counsel for the Company) shall be stamped or otherwise
imprinted with appropriate legends mandated by federal and state securities
laws.

     6.5  Publicity.  Except as required by law, no press release, public
statement, advertisement or similar publicity from any party hereunder with
respect to the participation of the Investor in the transactions contemplated
hereby (or any other matter relating to the Company and the Investor or its
affiliates) shall be issued or made without the prior consent of Investor.
Notwithstanding the foregoing, the Company may disclose Investor's investment in
the Company and the terms thereof and such other information previously approved
by Investor for inclusion in the Registration Statement.

7.   Miscellaneous.

     7.1  Governing Law. This Agreement shall be governed in all respects by the
laws of the State of Delaware as applied to agreements among Delaware residents
entered into and to be performed entirely within Delaware, without regard to the
conflict of law provisions thereof.

     7.2  Survival; Additional Securities. The representations and warranties
set forth in Sections 2 and 3 shall survive until the Closing. The covenants and
agreements set forth in Section 6 shall survive in accordance with their terms.
Any new, substituted or additional securities which are by reason of any stock
split, stock dividend, recapitalization or reorganization distributed with
respect to the Stock ("Stock Distributions") shall be immediately subject to the
covenants and agreements set forth in Section 6 to the same extent the Stock is
at such time covered by such provisions.

     7.3  Successors and Assigns. Except as otherwise expressly provided herein,
the provisions hereof shall inure to the benefit of, and be binding upon, the
respective successors and assigns of the parties hereto. Nothing in this
Agreement, express or implied, is intended to confer upon any party other than
the parties hereto or their respective successors and assigns any rights,
remedies, obligations, or liabilities under or by reason of this Agreement,
except as expressly provided in this Agreement. Notwithstanding anything to the
contrary contained herein, the covenants set forth in Section 6 shall not be
binding upon any entity (other than an affiliate of the Investor) which acquires
any shares of the Stock or a Stock Distribution in a transaction permitted
hereunder.

     7.4  Entire Agreement.  This Agreement constitutes the entire understanding
and agreement between the parties with regard to the subject matter hereof.
<PAGE>

     7.5   Notices.  Except as otherwise provided, all notices and other
communications required or permitted hereunder shall be in writing, shall be
effective when given, and shall in any event be deemed to be given upon receipt
or, if earlier, (i) five (5) days after deposit with the U.S. postal service or
other applicable postal service, if delivered by first class mail, postage
prepaid, (ii) upon delivery, if delivered by hand, (iii) one (1) business day
after the day of deposit with Federal Express or similar overnight courier,
freight prepaid, if delivered by overnight courier or (iv) one (1) business day
after the day of facsimile transmission, if delivered by facsimile transmission
with copy by first class mail, postage prepaid, and shall be addressed, (a) if
to the Investor, at the Investor's address set forth below its signature, or at
such other address as the Investor shall have furnished to the Company in
writing, or (b) if to the Company, at its address as set forth below its
signature, or at such other address as the Company shall have furnished to the
Investor in writing.

     7.6   Amendments and Waivers. Any term of this Agreement may be amended and
the observance of any term of the Agreement may be waived (either generally or
in a particular instance and either retroactively or prospectively) only with
the written consent of the Company and the Investor.

     7.7   Legal Fees. In the event of any action at law, suit in equity or
arbitration proceeding in relation to this Agreement or the Stock or any Stock
Distribution, the prevailing party shall be paid by the other party a reasonable
sum for the attorneys' fees and expenses incurred by such prevailing party.

     7.8   Expenses. Irrespective of whether the Closing is effected, the
Company and the Investor shall each pay their own costs and expenses incurred
with respect to the negotiation, execution, delivery and performance of this
Agreement.

     7.9   Titles and Subtitles. The titles of the paragraphs and subparagraphs
of this Agreement are for convenience of reference only and are not to be
considered in construing this Agreement.

     7.10  Counterparts. This Agreement may be executed in counterparts, each of
which shall be an original, but all of which together shall constitute one
instrument.

     7.11  Severability. If one or more provisions of this Agreement are held to
be unenforceable under applicable law, such provision shall be excluded from
this Agreement and the balance of the Agreement shall be interpreted as if such
provision were so excluded and shall be enforceable in accordance with its
terms.

     7.12  Confidentiality. The parties hereto agree that, except with the prior
written permission of the other party, it shall at all times keep confidential
and not divulge, furnish, or make accessible to anyone any confidential
information, knowledge, or data concerning or relating to the business or
financial affairs of such other party to which said party has been or shall
become privy by reason of this Agreement, discussions or negotiations relating
to this Agreement or the performance of its obligations hereunder.

     7.13  Termination.  This Stock Purchase Agreement shall terminate and be of
no further force or effect on the date on which the Company's IPO is
consummated, if Investor has not received the necessary approval required to
effect the investment contemplated by this agreement under the Hart-Scott-Rodino
Anti-Trust Improvement Act or its successor.  Notwithstanding the foregoing, if
the Closing has not occurred as of May 12, 2000, this agreement shall be
terminable at the option of the Investor.

                  [REMAINDER OF PAGE INTENTIONALLY LEFT BLANK]
<PAGE>

     IN WITNESS WHEREOF, the parties hereto have caused their duly authorized
officers to execute and deliver this Agreement as of the date first above
written.


                              FIRSTWORLD COMMUNICATIONS, INC.



                              By: /s/ Jeffrey L. Dykes
                                  --------------------

                              Name: Jeffrey L. Dykes
                                    ----------------

                              Title: Senior Vice President
                                     ---------------------


                              TPG FirstWorld I LLC



                              By: /s/ Richard A. Ekleberry
                                  ------------------------

                              Name: Richard A. Ekleberry
                                    --------------------

                              Title: Vice President and Secretary
                                     ----------------------------
<PAGE>

                                   EXHIBIT A
                                   ---------


[FirstWorld Communications, Inc. Amended and Restated Investor Rights Agreement




                                      A-1