Exhibit 4.2


 


	 NUMBER	
        NUMBER

        

        C

        

        SHARES

SEE REVERSE FOR

CERTAIN DEFINITIONS

CUSIP: G4035N 103 



 


GP-ACT III ACQUISITION CORP.

INCORPORATED UNDER THE LAWS OF THE CAYMAN ISLANDS

CLASS A ORDINARY SHARES


 


This 

Certifies


 


This Certifies that _______________________________________________________________________
is the owner of _______________________________________________________________________FULLY PAID AND NON-ASSESSABLE CLASS A ORDINARY
SHARES OF THE PAR VALUE OF U.S.$0.0001 EACH OF


 


GP-ACT III ACQUISITION CORP.

(THE “COMPANY”)


 


subject to the Company’s amended and restated memorandum
and articles of association and transferable on the register of members of the Company in person or by duly authorized attorney
upon surrender of this certificate properly endorsed.


 


The Company will be forced to redeem all of its Class A Ordinary
Shares if it is unable to complete a business combination by March [•], 2023, or such by later date approved by the Company’s
shareholders in accordance with the Company’s amended and restated memorandum and articles of association, all as more fully
described in the Company’s final prospectus dated March [•], 2021.


 


This certificate is not valid unless countersigned by the Transfer
Agent and registered by the Registrar of the Company.


 


Witness the facsimile signatures of its duly authorized officers.


 


	 	 	 
	[TITLE]	 	[TITLE]






     


     


    



GP-ACT III ACQUISITION CORP.


 


The Company will furnish without charge to each shareholder
who so requests the powers, designations, preferences and relative, participating, optional or other special rights of each class
of shares or series thereof of the Company and the qualifications, limitations, or restrictions of such preferences and/or rights.
This certificate and the shares represented thereby are issued and shall be held subject to all the provisions of the amended and
restated memorandum and articles of association and all amendments thereto and resolutions of the Board of Directors providing
for the issue of securities (copies of which may be obtained from the secretary of the Company), to all of which the holder of
this certificate by acceptance hereof assents.


 


The following abbreviations, when used in the inscription on
the face of this certificate, shall be construed as though they were written out in full according to applicable laws or regulations:


 


	 TEN COM	—  as tenants in common	UNIF GIFT MIN ACT —	________Custodian

________
	TEN ENT	—  as tenants by the entireties	 	(Cust)

(Minor)

under Uniform Gifts to Minors
	 	 	 	 
	JT TEN	—  as joint tenants with right of survivorship and not as tenants in common	 	Act                                      

(State)


 


Additional abbreviations may also be used though not in the
above list.


 


For value received, __________________ hereby sells, assigns
and transfers unto


 


	(PLEASE INSERT SOCIAL SECURITY OR OTHER IDENTIFYING NUMBER(S) OF ASSIGNEE(S))
	(PLEASE PRINT OR TYPEWRITE NAME(S) AND ADDRESS(ES), INCLUDING ZIP CODE, OF ASSIGNEE(S))
	 
	 
	Shares represented by the within Certificate, and does hereby irrevocably constitute and appoint
	Attorney to transfer the said shares on the register of members of the within named Company with full power of substitution in the premises.




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	Dated:
	
 


	
 


	
        NOTICE: THE SIGNATURE(S) TO THIS ASSIGNMENT MUST CORRESPOND
        WITH THE NAME AS WRITTEN UPON THE FACE OF THE CERTIFICATE IN EVERY PARTICULAR, WITHOUT ALTERATION OR ENLARGEMENT OR ANY CHANGE
        WHATEVER.

         

	Signature(s) Guaranteed:

By
	
 


	
 




THE SIGNATURE(S) MUST BE GUARANTEED BY AN ELIGIBLE GUARANTOR
INSTITUTION (BANKS, STOCKBROKERS, SAVINGS AND LOAN ASSOCIATIONS AND CREDIT UNIONS WITH MEMBERSHIP IN AN APPROVED SIGNATURE GUARANTEE
MEDALLION PROGRAM, PURSUANT TO S.E.C. RULE 17Ad-15 UNDER THE UNITED STATES SECURITIES EXCHANGE ACT OF 1934, AS AMENDED).


 


In each case, as more fully described in the Company’s
final prospectus dated March [•], 2021, the holder(s) of this certificate shall be entitled to receive a pro rata portion
of certain funds held in the trust account established in connection with its initial public offering only in the event that (i)
the Company redeems the Class A Ordinary Shares sold in its initial public offering and liquidates because it does not consummate
an initial business combination by March [•], 2023, or by such later date approved by the Company’s shareholders in
accordance with the Company’s amended and restated memorandum and articles of association, (ii) the Company redeems the Class
A Ordinary Shares sold in its initial public offering in connection with a shareholder vote to amend the Company’s amended
and restated memorandum and articles of association (A) to modify the substance or timing of the Company’s obligation to
allow redemption in connection with the Company’s initial business combination or to redeem 100% of the Class A Ordinary
Shares if it does not complete its initial business combination by March [•], 2023, or by such later date approved by the
Company’s shareholders in accordance with the Company’s amended and restated memorandum and articles of association,
or (B) with respect to any other provision relating to the holder(s)’(s) rights or pre-initial business combination activity,
or (iii) if the holder(s) seek(s) to redeem for cash his, her, its or their respective Class A Ordinary Shares in connection with
a tender offer (or proxy solicitation, solely in the event the Company seeks shareholder approval of the proposed initial business
combination) setting forth the details of a proposed initial business combination. In no other circumstances shall the holder(s)
have any right or interest of any kind to or in the trust account.




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