<PAGE>
                                                                     Exhibit 4.6


     ________________________________________________________________

                     COMMON SECURITIES GUARANTEE AGREEMENT


                      PUGET SOUND ENERGY CAPITAL TRUST II


                           Dated as of May 18, 2001


     _________________________________________________________________

<PAGE>

                                   CONTENTS

ARTICLE I  DEFINITIONS AND INTERPRETATION...............................   2

     SECTION 1.1    Definitions and Interpretation......................   2

ARTICLE II  GUARANTEE...................................................   3

     SECTION 2.1    Guarantee...........................................   3

     SECTION 2.2    Waiver of Notice and Demand.........................   3

     SECTION 2.3    Obligations Not Affected............................   3

     SECTION 2.4    Rights of Holders...................................   4

     SECTION 2.5    Guarantee of Payment................................   4

     SECTION 2.6    Subrogation.........................................   5

     SECTION 2.7    Independent Obligations.............................   5

ARTICLE III  LIMITATION OF TRANSACTIONS; SUBORDINATION..................   5

     SECTION 3.1    Limitation of Transactions..........................   5

     SECTION 3.2    Ranking.............................................   6

ARTICLE IV  TERMINATION.................................................   6

     SECTION 4.1    Termination.........................................   6

     ARTICLE V      MISCELLANEOUS.......................................   6

     SECTION 5.1    Successors and Assigns..............................   6

     SECTION 5.2    Amendments..........................................   7

     SECTION 5.3    Notices.............................................   7

     SECTION 5.4    Benefit.............................................   8

     SECTION 5.5    Governing Law.......................................   8
<PAGE>

                     COMMON SECURITIES GUARANTEE AGREEMENT

     This GUARANTEE AGREEMENT (the "Common Securities Guarantee"), dated as of
May 18, 2001, is executed and delivered by Puget Sound Energy, Inc., a
Washington corporation (the "Guarantor"), for the benefit of the Holders (as
defined herein) from time to time of the Common Securities (as defined herein)
of Puget Sound Energy Capital Trust II, a Delaware statutory business trust (the
"Issuer").

     WHEREAS, pursuant to an Amended and Restated Declaration of Trust (the
"Declaration"), dated as of May 18, 2001, among the trustees of the Issuer named
therein, the Guarantor, as sponsor, and the holders from time to time of
undivided beneficial interests in the assets of the Issuer, the Issuer is
issuing on the date hereof 247,440 common securities, having an aggregate stated
liquidation amount of $6,186,000 designated the 8.40% Trust Originated Common
Securities (the "Common Securities");

     WHEREAS, as incentive for the Holders to purchase the Common Securities,
the Guarantor desires to irrevocably and unconditionally agree, to the extent
set forth in this Common Securities Guarantee, to pay to the Holders of the
Common Securities the Guarantee Payments (as defined herein) and to make certain
other payments on the terms and conditions set forth herein; and

     WHEREAS, the Guarantor is also executing and delivering a guarantee
agreement (the "Preferred Securities Guarantee") in substantially identical
terms to this Common Securities Guarantee for the benefit of the holders of the
Preferred Securities (as defined herein), except that if an Event of Default (as
defined in the Indenture), has occurred and is continuing, the rights of Holders
of the Common Securities to receive Guarantee Payments under this Common
Securities Guarantee are subordinated to the rights of holders of Preferred
Securities to receive Guarantee Payments under the Preferred Securities
Guarantee.

     NOW, THEREFORE, in consideration of the purchase by each Holder of Common
Securities, which purchase the Guarantor hereby agrees shall benefit the
Guarantor, the Guarantor executes and delivers this Common Securities Guarantee
for the benefit of the Holders.
<PAGE>

                  ARTICLE I  DEFINITIONS AND INTERPRETATION

SECTION 1.1   Definitions and Interpretation

     In this Common Securities Guarantee, unless the context otherwise requires:

     (a)   Capitalized terms used in this Common Securities Guarantee but not
defined in the preamble above have the respective meanings assigned to them in
this Section 1.1;

     (b)   Terms defined in the Declaration as of the date of execution of this
Common Securities Guarantee have the same meaning when used in this Common
Securities Guarantee unless otherwise defined in this Common Securities
Guarantee;

     (c)   a term defined anywhere in this Common Securities Guarantee has the
same meaning throughout;

     (d)   all references to "the Common Securities Guarantee" or "this Common
Securities Guarantee" are to this Common Securities Guarantee modified,
supplemented or amended from time to time;

     (e)   all references in this Common Securities Guarantee to Articles and
Sections are to Articles and Sections of this Common Securities Guarantee unless
otherwise specified; and

     (f)   a reference to the singular includes the plural and vice versa.

     "Guarantee Payments" shall mean the following payments or distributions,
without duplication, with respect to the Common Securities, to the extent not
paid or made by the Issuer:  (i) any accrued and unpaid Distributions (as
defined in the Declaration) that are required to be paid on such Common
Securities to the extent the Issuer shall have funds available therefor, (ii)
the redemption price, including all accrued and unpaid Distributions to the date
of redemption (the "Redemption Price") to the extent the Issuer has funds
available therefor, with respect to any Common Securities called for redemption
by the Issuer, and (iii) upon a voluntary or involuntary dissolution, winding-up
or termination of the Issuer (other than in connection with the distribution of
Debentures to the Holders in exchange for Common Securities as provided in the
Declaration), the lesser of (a) the aggregate of the liquidation amount and all
accrued and unpaid Distributions on the Common Securities to the date of
payment, to the extent the Issuer shall have funds available therefor, and (b)
the amount of assets of the Issuer remaining available for distribution

                                      -2-
<PAGE>

to Holders in liquidation of the Issuer (in either case, the "Liquidation
Distribution"). If an Event of Default (as defined in the Indenture) has
occurred and is continuing, the rights of Holders of the Common Securities to
receive Guarantee Payments under this Common Securities Guarantee are
subordinated to the rights of holders of Preferred Securities to receive
Guarantee Payments.

     "Holder" shall mean any holder, as registered on the books and records of
the Issuer, of any Common Securities.

     "Preferred Securities" mean the securities representing preferred undivided
beneficial interests in the assets of the Issuer.

                             ARTICLE II  GUARANTEE

SECTION 2.1   Guarantee

     The Guarantor irrevocably and unconditionally agrees to pay in full to the
Holders the Guarantee Payments (without duplication of amounts theretofore paid
by the Issuer), as and when due, regardless of any defense, right of set-off or
counterclaim which the Issuer may have or assert.  The Guarantor's obligation to
make a Guarantee Payment may be satisfied by direct payment of the required
amounts by the Guarantor to the Holders or by causing the Issuer to pay such
amounts to the Holders.

SECTION 2.2   Waiver of Notice and Demand

     The Guarantor hereby waives notice of acceptance of this Common Securities
Guarantee and of any liability to which it applies or may apply, presentment,
demand for payment, any right to require a proceeding first against the Issuer
or any other Person before proceeding against the Guarantor, protest, notice of
nonpayment, notice of dishonor, notice of redemption and all other notices and
demands.

SECTION 2.3   Obligations Not Affected

     Except as otherwise provided herein, the obligations, covenants, agreements
and duties of the Guarantor under this Common Securities Guarantee shall in no
way be affected or impaired by reason of the happening from time to time of any
of the following:

     (a) the release or waiver, by operation of law or otherwise, of the
performance or observance by the Issuer of any express or implied agreement,

                                      -3-
<PAGE>

covenant, term or condition relating to the Common Securities to be performed or
observed by the Issuer;

     (b) the extension of time for the payment by the Issuer of all or any
portion of the Distributions, Redemption Price, Liquidation Distribution or any
other sums payable under the terms of the Common Securities or the extension of
time for the performance of any other obligation under, arising out of, or in
connection with, the Common Securities (other than an extension of time for
payment of Distributions, Redemption Price, Liquidation Distribution or other
sum payable that results from the extension of any interest payment period on
the Debentures or any extension of the maturity date of the Debentures permitted
by the Indenture);

     (c) any failure, omission, delay or lack of diligence on the part of the
Holders to enforce, assert or exercise any right, privilege, power or remedy
conferred on the Holders pursuant to the terms of the Common Securities, or any
action on the part of the Issuer granting indulgence or extension of any kind;

     (d) the voluntary or involuntary liquidation, dissolution, sale of any
collateral, receivership, insolvency, bankruptcy, assignment for the benefit of
creditors, reorganization, arrangement, composition or readjustment of debt of,
or other similar proceedings affecting, the Issuer or any of the assets of the
Issuer;

     (e) any invalidity of, or defect or deficiency in, the Common Securities;

     (f) the settlement or compromise of any obligation guaranteed hereby or
hereby incurred; or

     (g) any other circumstance whatsoever that might otherwise constitute a
legal or equitable discharge or defense of a guarantor, it being the intent of
this Section 2.3 that the obligations of the Guarantor hereunder shall be
absolute and unconditional under any and all circumstances.

There shall be no obligation of the Holders to give notice to, or obtain consent
of, the Guarantor with respect to the happening of any of the foregoing.

SECTION 2.4   Rights of Holders

     The Guarantor expressly acknowledges that any Holder of Common Securities
may institute a legal proceeding directly against the Guarantor to enforce its
rights under this Common Securities Guarantee, without first instituting a legal
proceeding against the Issuer or any other Person.

                                      -4-
<PAGE>

SECTION 2.5   Guarantee of Payment

     This Common Securities Guarantee creates a guarantee of payment and not of
collection.

SECTION 2.6   Subrogation

     The Guarantor shall be subrogated to all (if any) rights of the Holders of
Common Securities against the Issuer in respect of any amounts paid to such
Holders by the Guarantor under this Common Securities Guarantee; provided,
however, that the Guarantor shall not (except to the extent required by
mandatory provisions of law) be entitled to enforce or exercise any right that
it may acquire by way of subrogation or any indemnity, reimbursement or other
agreement, in all cases as a result of payment under this Common Securities
Guarantee, if, at the time of any such payment, any amounts are due and unpaid
under this Common Securities Guarantee.  If any amount shall be paid to the
Guarantor in violation of the preceding sentence, the Guarantor agrees to hold
such amount in trust for the Holders and to pay over such amount to the Holders.

SECTION 2.7   Independent Obligations

     The Guarantor acknowledges that its obligations hereunder are independent
of the obligations of the Issuer with respect to the Common Securities and that
the Guarantor shall be liable as principal and as debtor hereunder to make
Guarantee Payments pursuant to the terms of this Common Securities Guarantee
notwithstanding the occurrence of any event referred to in subsections (a)
through (g), inclusive, of Section 2.3 hereof.

            ARTICLE III  LIMITATION OF TRANSACTIONS; SUBORDINATION

SECTION 3.1   Limitation of Transactions

     So long as any Common Securities remain outstanding, if (i) the Guarantor
shall be in default with respect to its Guarantee Payments or other obligations
hereunder, or (ii) there shall have occurred any Event of Default under the
Indenture or an event of default under the Declaration, then (a) the Guarantor
shall not declare or pay any dividend on, or make any distributions with respect
to, or redeem, purchase, acquire or make a liquidation payment with respect to,
any of its capital stock, (b) the Guarantor shall not make any payment of
interest, principal or premium, if any, on or repay, repurchase or redeem any
debt securities (including guarantees) issued by the Guarantor which rank pari
passu with or junior to the Debentures or

                                      -5-
<PAGE>

(c) the Guarantor shall not make any guarantee payments with respect to the
foregoing (other than, with respect to clauses (a), (b) and (c), (i) dividends
or distributions in shares of, or options, warrants or rights to subscribe for
or purchase shares of, common stock of the Guarantor; (ii) any declaration of a
dividend in connection with the implementation of a shareholder's rights plan,
or the issuance of stock under any such plan in the future, or the redemption or
repurchase of any such rights pursuant thereto; (iii) payments under the
Preferred Securities Guarantee Agreement; (iv) as a direct result of, and only
to the extent required in order to avoid the issuance of fractional shares of
capital stock, following a reclassification of the Guarantor's capital stock or
the exchange or conversion of one class or series of the Guarantor's capital
stock for another class or series of the Guarantor's capital stock; and (v) the
purchase of fractional interests in shares of the Guarantor's capital stock
pursuant to the conversion or exchange provisions of such capital stock or the
security being converted or exchanged).

SECTION 3.2   Ranking

     This Common Securities Guarantee will constitute an unsecured obligation of
the Guarantor and will rank (i) subordinate and junior in right of payment to
all other liabilities of the Guarantor, (ii) pari passu with the most senior
preferred or preference stock now or hereafter issued by the Guarantor and with
any guarantee now or hereafter entered into by the Guarantor in respect of any
preferred or preference stock of any Affiliate of the Guarantor, and (iii)
senior to the Guarantor's common stock.

                            ARTICLE IV  TERMINATION
SECTION 4.1   Termination

     This Common Securities Guarantee shall terminate (i) upon full payment of
the Redemption Price of all Common Securities, (ii) upon the distribution of the
Debentures to the Holders of all of the Common Securities, or (iii) or upon full
payment of the amounts payable in accordance with the Declaration upon
liquidation of the Issuer. Notwithstanding the foregoing, this Common Securities
Guarantee will continue to be effective or will be reinstated, as the case may
be, if at any time any Holder of Common Securities must restore payment of any
sums paid under the Common Securities or under this Common Securities Guarantee.

                                      -6-
<PAGE>

                           ARTICLE V  MISCELLANEOUS

SECTION 5.1   Successors and Assigns

     All guarantees and agreements contained in this Common Securities Guarantee
shall bind the successors, assigns, receivers, trustees and representatives of
the Guarantor and shall inure to the benefit of the Holders of the Common
Securities then outstanding.

SECTION 5.2   Amendments

     Except with respect to any changes which do not adversely affect the rights
of Holders (in which case no consent of Holders will be required), this Common
Securities Guarantee may only be amended with the prior approval of the Holders
of at least a majority in liquidation amount of all the outstanding Common
Securities.  The provisions of Section 12.2 of the Declaration with respect to
meetings of Holders of the Securities apply to the giving of such approval.

SECTION 5.3   Notices

     All notices provided for in this Common Securities Guarantee shall be in
writing, duly signed by the party giving such notice, and shall be delivered,
telecopied or mailed by registered or certified mail, as follows:

     (a)   if given to the Issuer, in care of the Regular Trustees at the
           Issuer's mailing address set forth below (or such other address as
           the Issuer may give notice of to the Holders of the Common
           Securities):

           Puget Sound Energy Capital Trust II
           c/o Puget Sound Energy, Inc.
           411 108/th/ Avenue N.E.
           Bellevue, Washington  98004-5515
           Attention: Richard L. Hawley
                      Donald E. Gaines
           Facsimile (425) 462-3300

     (b)   if given to the Guarantor, at the Guarantor's mailing address set
           forth below (or such other address as the Guarantor may give notice
           of to the Holders of the Common Securities):

                                      -7-
<PAGE>

           Puget Sound Energy, Inc.
           411 108/th/ Avenue N.E.
           Bellevue, Washington 98004-5515
           Attention: Donald E. Gaines
                      Vice President and Treasurer
           Facsimile (425) 462-3300

     (c)   if given to any Holder of Common Securities, at the address set forth
           on the books and records of the Issuer.

     All such notices shall be deemed to have been given when received in
person, telecopied with receipt confirmed, or mailed by first class mail,
postage prepaid except that if a notice or other document is refused delivery or
cannot be delivered because of a changed address of which no notice was given,
such notice or other document shall be deemed to have been delivered on the date
of such refusal or inability to deliver.

SECTION 5.4   Benefit

     This Common Securities Guarantee is solely for the benefit of the Holders
of the Common Securities and is not separately transferable from the Common
Securities.

SECTION 5.5   Governing Law

     This Common Securities Guarantee shall be governed by, and construed and
interpreted in accordance with, the laws of the State of Washington.



     (The remainder of this page has intentionally been left blank)

                                      -8-
<PAGE>

     THIS COMMON SECURITIES GUARANTEE is executed as of the day and year first
above written.


                                 PUGET SOUND ENERGY, INC., as Guarantor

                                 By:   /s/ Donald E. Gaines
                                     ----------------------------------
                                     Donald E. Gaines
                                     Vice President and Treasurer

                                      -9-