EX-10.1





 Exhibit 10.1

March 1, 2021 
 Haymaker Acquisition Corp.
III 
 501 Madison Avenue, Floor 12 
 New York, NY 10022 

(212) 616-9600 
 Re:
Initial Public Offering 
 Ladies and Gentlemen: 

This letter (this “Letter Agreement”) is being delivered to you in accordance with the Underwriting Agreement (the
“Underwriting Agreement”) to be entered into by and among Haymaker Acquisition Corp. III, a Delaware corporation (the “Company”) and Citigroup Global Markets Inc. and Cantor Fitzgerald & Co. (collectively,
the “Representatives”), relating to an underwritten initial public offering (the “Public Offering”), of 34,500,000 of the Company’s units (including up to 4,500,000 units that may be purchased to cover
over-allotments, if any) (the “Units”), each comprised of one share of the Company’s Class A common stock, par value $0.0001 per share (the “Common Stock”), and
one-fourth of one redeemable warrant. Each whole Warrant (each, a “Warrant”) entitles the holder thereof to purchase one share of Common Stock at a price of $11.50 per share, subject to
adjustment. The Units will be sold in the Public Offering pursuant to a registration statement on Form S-1 and prospectus (the “Prospectus”) filed by the Company with the U.S. Securities and
Exchange Commission (the “Commission”) and the Company has applied to have the Units listed on the Nasdaq Capital Market. Certain capitalized terms used herein are defined in paragraph 11 hereof. 

In order to induce the Company and the Representatives to enter into the Underwriting Agreement and to proceed with the Public Offering and
for other good and valuable consideration, the receipt and sufficiency of which are hereby acknowledged, Haymaker Sponsor III LLC (the “Sponsor”) and each of the undersigned individuals, each of whom is a member of the
Company’s board of directors and/or management team (each, an “Insider” and collectively, the “Insiders”), hereby severally (and not jointly and severally) agrees with the Company as follows: 

1. The Sponsor and each Insider agrees that if the Company seeks stockholder approval of a proposed Business Combination,
then in connection with such proposed Business Combination, it, he or she shall (i) vote any shares of Capital Stock owned by it, him or her in favor of any proposed Business Combination and (ii) not redeem any shares of Common Stock owned
by it, him or her in connection with such stockholder approval. If the Company seeks to consummate a proposed Business Combination by engaging in a tender offer, the Sponsor and each Insider agrees that it, he or she will not sell or tender any
shares of Capital Stock owned by it, him or her in connection therewith. 
 2. The Sponsor and each Insider hereby
agrees that in the event that the Company fails to consummate a Business Combination within 24 months from the closing of the Public Offering, or such later period approved by the Company’s stockholders in accordance with the Company’s
amended and restated certificate of incorporation (the “Charter”), the Sponsor and each Insider shall take all reasonable steps to cause the Company to (i) cease all operations except for the purpose of winding up, (ii) as
promptly as reasonably possible but not more than 10 business days thereafter, subject to lawfully available funds therefor, redeem 100% of the Common Stock sold as part of the Units in the Public Offering (the “Offering Shares”),
at a per-share price, payable in cash, equal to the aggregate amount then on deposit in the Trust Account, including interest (net of amounts withdrawn to pay the Company’s taxes (“Permitted
Withdrawals”) and less up to $100,000 of interest to pay dissolution expenses), divided by the number of then outstanding Offering Shares, which redemption will completely extinguish all Public Stockholders’ rights as stockholders
(including the right to receive further liquidating distributions, if any), subject to applicable law, and (iii) as promptly as reasonably possible following such redemption, subject to the approval of the Company’s remaining stockholders
and the Company’s board of directors, dissolve and liquidate, subject in each case to the Company’s obligations under Delaware law to provide for claims of creditors and other requirements of applicable law. The Sponsor and each Insider
agree to not propose any amendment to the Charter that would modify the substance or timing of the Company’s obligation to redeem 100% of the Offering Shares if the 












 
Company does not complete a Business Combination within the required time period set forth in the Charter or with respect to any other material provisions relating to stockholders’ rights or
pre-initial business combination activity, unless the Company provides its Public Stockholders with the opportunity to redeem their Offering Shares upon approval of any such amendment at a per-share price, payable in cash, equal to the aggregate amount then on deposit in the Trust Account, including interest (net of Permitted Withdrawals), divided by the number of then outstanding Offering Shares.

 The Sponsor and each Insider acknowledges that it, he or she has no right, title, interest or claim of any kind in or to
any monies held in the Trust Account as a result of any liquidation of the Company with respect to the Founder Shares held by it, him or her. The Sponsor and each Insider hereby further waive, with respect to any shares of Common Stock held by it,
him or her, if any, any redemption rights it, he or she may have in connection with the consummation of a Business Combination, including, without limitation, any such rights available in the context of a stockholder vote to approve such Business
Combination or in the context of a tender offer made by the Company to purchase shares of Common Stock (although the Sponsor, the Insiders and their respective affiliates shall be entitled to redemption and liquidation rights with respect to any
Offering Shares it or they hold if the Company fails to consummate a Business Combination within the time period set forth in the Charter or in connection with a stockholder vote to approve an amendment to the Charter to modify the substance or
timing of the Company’s obligation to redeem 100% of the Offering Shares if the Company does not complete a Business Combination within the time period set forth in the Charter or with respect to any other material provisions relating to
stockholders’ rights or pre-initial business combination activity). 

3. During the period commencing on the effective date of the Underwriting Agreement and ending 180 days after such date,
the Sponsor and each Insider shall not, without the prior written consent of the Representatives, (i) sell, offer to sell, contract or agree to sell, hypothecate, pledge, grant any option to purchase or otherwise dispose of or agree to dispose
of, directly or indirectly, or establish or increase a put equivalent position or liquidate or decrease a call equivalent position within the meaning of Section 16 of the Securities Exchange Act of 1934, as amended (the “Exchange
Act”), and the rules and regulations of the Commission promulgated thereunder, with respect to any Units, shares of Capital Stock, Warrants or any securities convertible into, or exercisable, or exchangeable for, shares of Common Stock
owned by it, him or her, (ii) enter into any swap or other arrangement that transfers to another, in whole or in part, any of the economic consequences of ownership of any Units, shares of Capital Stock, Warrants or any securities convertible
into, or exercisable, or exchangeable for, shares of Common Stock owned by it, him or her, whether any such transaction is to be settled by delivery of such securities, in cash or otherwise, or (iii) publicly announce any intention to effect
any transaction specified in clause (i) or (ii). 
 4. In the event of the liquidation of the Trust Account, the
Sponsor (which for purposes of clarification shall not extend to any other shareholders, members or managers of the Sponsor or any other Insider) agrees to indemnify and hold harmless the Company against any and all loss, liability, claim, damage
and expense whatsoever (including, but not limited to, any and all legal or other expenses reasonably incurred in investigating, preparing or defending against any litigation, whether pending or threatened, or any claim whatsoever) to which the
Company may become subject as a result of any claim by (i) any third party for services rendered or products sold to the Company or (ii) any prospective target business with which the Company has entered into a letter of intent,
confidentiality or other similar agreement for a Business Combination (a “Target”); provided, however, that such indemnification of the Company by the Sponsor (x) shall apply only to the extent necessary to
ensure that such claims by a third party or a Target do not reduce the amount of funds in the Trust Account to below the lesser of (i) $10.00 per Offering Share or (ii) the actual amount per Offering Share held in the Trust Account as of the
date of the liquidation of the Trust Account, if less than $10.00 per Offering Share is then held in the Trust Account due to reductions in the value of the trust assets less Permitted Withdrawals, (y) shall not apply to any claims by a third
party (including a Target) that executed a waiver of any and all rights to the monies held in the Trust Account (whether or not such waiver is enforceable) and (z) shall not apply to any claims under the Company’s indemnity of the
Representatives against certain liabilities, including liabilities under the Securities Act of 1933, as amended. The Sponsor shall have the right to defend against any such claim with counsel of its choice reasonably satisfactory to the Company if,
within 15 days following written receipt of notice of the claim to the Sponsor, the Sponsor notifies the Company in writing that it shall undertake such defense. For the avoidance of doubt, none of the Company’s officers or directors will
indemnify the Company for claims by third parties, including, without limitation, claims by vendors and prospective target businesses. 












 5. To the extent that the Representatives do not exercise their
over-allotment option to purchase up to an additional 4,500,000 Units within 45 days from the date of the Prospectus (and as further described in the Prospectus), the Sponsor agrees to forfeit, at no cost, a number of Founder Shares in the aggregate
equal to the product of 1,125,000 multiplied by a fraction, (i) the numerator of which is 4,500,000 minus the number of Units purchased by the Representatives upon the exercise of its over-allotment option, and (ii) the denominator of
which is 4,500,000. The forfeiture will be adjusted to the extent that the over-allotment option is not exercised in full by the Representatives so that the Initial Stockholders will own an aggregate of 20.0% of the Company’s issued and
outstanding shares of Capital Stock after the Public Offering. To the extent that the size of the Public Offering is increased or decreased, the Company will effect a capitalization or share repurchase, redemption or stock split or other appropriate
mechanism, as applicable, immediately prior to the consummation of the Public Offering in such amount as to maintain the ownership of the Capital Stock of the Initial Stockholders prior to the Public Offering at 20.0% of the Company’s issued
and outstanding Capital Stock upon the consummation of the Public Offering. In connection with such increase or decrease in the size of the Public Offering, (A) references to 4,500,000 in the numerator and denominator of the formula in the
first sentence of this paragraph shall be changed to a number equal to 15% of the number of shares included in the Units issued in the Public Offering and (B) the reference to 1,125,000 in the formula set forth in the immediately preceding
sentence shall be adjusted to such number of Founder Shares that the Sponsor would have to return to the Company in order to hold (with all of the Initial Stockholders) an aggregate of 20.0% of the Company’s issued and outstanding Capital Stock
after the Public Offering. 
 6. (a) The Sponsor and each Insider hereby agrees and acknowledges that: (i) the
Representatives and the Company would be irreparably injured in the event of a breach by such Sponsor or an Insider of its, his or her obligations under paragraphs 1, 2, 3, 4, 5, 7(a), 7(b), and 9, as applicable, of this Letter Agreement
(ii) monetary damages may not be an adequate remedy for such breach and (iii) the non-breaching party shall be entitled to injunctive relief, in addition to any other remedy that such party may have
in law or in equity, in the event of such breach. 
 7. (a) The Sponsor and each Insider agrees that it, he or she shall
not Transfer any Founder Shares (or shares of Common Stock issuable upon conversion thereof) until the earlier of (A) one year after the completion of the Company’s initial Business Combination or (B) subsequent to the Business
Combination, (x) if the last reported sale price of the Common Stock equals or exceeds $12.00 per share (as adjusted for stock splits, stock dividends, reorganizations, recapitalizations and the like) for any 20 trading days within any 30-trading day period commencing at least 150 days after the Company’s initial Business Combination or (y) the date on which the Company completes a liquidation, merger, capital stock exchange,
reorganization or other similar transaction that results in all of the Company’s stockholders having the right to exchange their shares of Common Stock for cash, securities or other property (the “Founder Shares Lock-up Period”). 
 (b) The Sponsor and each Insider agree that it, he or she
shall not Transfer any Private Placement Warrants (or shares of Common Stock issued or issuable upon the exercise of the Private Placement Warrants) until 30 days after the completion of a Business Combination (the “Private Placement
Warrants Lock-up Period”, together with the Founder Shares Lock-up Period, the “Lock-up Periods”). 

(c) Notwithstanding the provisions set forth in paragraphs 3 and 7(a) and (b), Transfers of the Founder Shares, Private
Placement Warrants and shares of Common Stock issued or issuable upon the exercise or conversion of the Private Placement Warrants or the Founder Shares and that are held by the Sponsor, any Insider or any of their permitted transferees (that have
complied with this paragraph 7(c)), are permitted (a) to the Company’s officers or directors, any affiliates or family members of any of the Company’s officers or directors, any members of the Sponsor, or any affiliates of the
Sponsor; (b) in the case of an individual, transfers by gift to a member of the individual’s immediate family, to a trust, the beneficiary of which is a member of the individual’s immediate family or an affiliate of such person, or to
a charitable organization; (c) in the case of an individual, transfers by virtue of laws of descent and distribution upon death of the individual; (d) in the case of an individual, transfers pursuant to a qualified domestic relations
order; (e) transfers by private sales or transfers made in connection with the consummation of a Business 












 
Combination at prices no greater than the price at which the securities were originally purchased; (f) transfers in the event of the Company’s liquidation prior to the completion of an
initial Business Combination; (g) transfers by virtue of the laws of the State of Delaware or the Sponsor’s limited liability company agreement upon dissolution of the Sponsor; (h) in the event of the Company’s completion of a
liquidation, merger, stock exchange, reorganization or other similar transaction which results in all of the Company’s public stockholders having the right to exchange their shares of Class A common stock for cash, securities or other
property subsequent to the completion of the initial business combination; (i) to a nominee or custodian of a person or entity to whom a disposition or transfer would be permissible under clauses (a) through (h) above; provided,
however, that in the case of clauses (a) through (e) and (i), these permitted transferees must enter into a written agreement with the Company agreeing to be bound by the transfer restrictions herein and the other restrictions contained
in this Agreement (including provisions relating to voting, the Trust Account and liquidating distributions). 
 8. The
Sponsor and each Insider represent and warrant that it, he or she has never been suspended or expelled from membership in any securities or commodities exchange or association or had a securities or commodities license or registration denied,
suspended or revoked. Each Insider’s biographical information furnished to the Company (including any such information included in the Prospectus) is true and accurate in all respects and does not omit any material information with respect to
the Insider’s background. The Sponsor and each Insider’s questionnaire furnished to the Company is true and accurate in all respects. The Sponsor and each Insider represents and warrants that: it, he or she is not subject to or a
respondent in any legal action for, any injunction, cease-and-desist order or order or stipulation to desist or refrain from any act or practice relating to the offering
of securities in any jurisdiction; it, he or she has never been convicted of, or pleaded guilty to, any crime (i) involving fraud, (ii) relating to any financial transaction or handling of funds of another person, or (iii) pertaining
to any dealings in any securities and it, he or she is not currently a defendant in any such criminal proceeding. 

9. Except as disclosed in the Prospectus, neither the Sponsor nor any Insider nor any affiliate of the Sponsor or any
Insider, nor any director or officer of the Company, shall receive from the Company any finder’s fee, reimbursement, consulting fee, monies in respect of any repayment of a loan or other compensation prior to, or in connection with any services
rendered in order to effectuate the consummation of the Company’s initial Business Combination (regardless of the type of transaction that it is), other than the following, none of which will be made from the proceeds held in the Trust Account
prior to the completion of the initial Business Combination: repayment of a loan and advances of up to $300,000 made to the Company by the Sponsor to cover expenses related to the organization of the Company and the Public Offering; payment to an
affiliate of the Sponsor for certain office space, utilities and secretarial and administrative support as may be reasonably required by the Company for a total of $20,000 per month; reimbursement for any reasonable out-of-pocket expenses related to identifying, investigating and consummating an initial Business Combination, and repayment of loans, if any, and on such terms as to be determined by the
Company from time to time, made by the Sponsor or certain of the Company’s officers and directors to finance transaction costs in connection with an intended initial Business Combination, provided, that, if the Company does not consummate an
initial Business Combination, a portion of the working capital held outside the Trust Account may be used by the Company to repay such loaned amounts so long as no proceeds from the Trust Account are used for such repayment. Up to $1,500,000 of such
loans may be convertible into warrants of the post Business Combination entity at a price of $1.50 per warrant at the option of the lender. Such warrants would be identical to the Private Placement Warrants, including as to exercise price,
exercisability and exercise period. 
 10. The Sponsor and each Insider has full right and power, without violating any
agreement to which it is bound (including, without limitation, any non-competition or non-solicitation agreement with any employer or former employer), to enter into
this Letter Agreement and, as applicable, to serve as an officer and/or a director on the board of directors of the Company and hereby consents to being named in the Prospectus as an officer and/or a director of the Company. 

11. As used herein, (i) “Business Combination” shall mean a merger, capital stock exchange, asset
acquisition, stock purchase, reorganization or similar business combination, involving the Company and one or more businesses; (ii) “Capital Stock” shall mean, collectively, the Common Stock and the Founder Shares;













 
(iii) “Founder Shares” shall mean the 8,625,000 shares of the Company’s Class B common stock, par value $0.0001 per share, (or 7,500,000 shares if the over-allotment
option is not exercised by the Representatives) initially held by the Sponsor, officers, independent directors and/or director nominees and advisors of the Company; (iv) “Initial Stockholders” shall mean the Sponsor and any other
holder of Founder Shares immediately prior to the Public Offering; (v) “Private Placement Warrants” shall mean the warrants to purchase up to 5,333,333 shares of Common Stock of the Company (or 5,933,333 shares of Common Stock if
the over-allotment option is exercised in full) that the Sponsor and certain other investors have agreed to purchase for an aggregate purchase price of $8,000,000 in the aggregate (or $8,900,000 if the over-allotment option is exercised in full), or
$1.50 per warrant, in a private placement that shall occur simultaneously with the consummation of the Public Offering; (vi) “Public Stockholders” shall mean the holders of securities issued in the Public Offering; (vii)
“Trust Account” shall mean the trust fund into which a portion of the net proceeds of the Public Offering and the sale of the Private Placement Warrants shall be deposited; and (viii) “Transfer” shall mean the
(a) sale or assignment of, offer to sell, contract or agreement to sell, hypothecate, pledge, grant of any option to purchase or otherwise dispose of or agreement to dispose of, directly or indirectly, or establishment or increase of a put
equivalent position or liquidation with respect to or decrease of a call equivalent position within the meaning of Section 16 of the Exchange Act and the rules and regulations of the Commission promulgated thereunder with respect to, any
security, (b) entry into any swap or other arrangement that transfers to another, in whole or in part, any of the economic consequences of ownership of any security, whether any such transaction is to be settled by delivery of such securities,
in cash or otherwise, or (c) public announcement of any intention to effect any transaction specified in clause (a) or (b). 

12. This Letter Agreement constitutes the entire agreement and understanding of the parties hereto in respect of the
subject matter hereof and supersedes all prior understandings, agreements, or representations by or among the parties hereto, written or oral, to the extent they relate in any way to the subject matter hereof or the transactions contemplated hereby.
This Letter Agreement may not be changed, amended, modified or waived (other than to correct a typographical error) as to any particular provision, except by a written instrument executed by all parties hereto. 

13. Except as otherwise provided herein, no party hereto may assign either this Letter Agreement or any of its rights,
interests, or obligations hereunder without the prior written consent of the other parties. Any purported assignment in violation of this paragraph shall be void and ineffectual and shall not operate to transfer or assign any interest or title to
the purported assignee. This Letter Agreement shall be binding on the Sponsor and each Insider and their respective successors, heirs and assigns and permitted transferees. 

14. Nothing in this Letter Agreement shall be construed to confer upon, or give to, any person or entity other than the
parties hereto any right, remedy or claim under or by reason of this Letter Agreement or of any covenant, condition, stipulation, promise or agreement hereof. All covenants, conditions, stipulations, promises and agreements contained in this Letter
Agreement shall be for the sole and exclusive benefit of the parties hereto and their successors, heirs, personal representatives and assigns and permitted transferees. 

15. This Letter Agreement may be executed in any number of original or facsimile counterparts and each of such
counterparts shall for all purposes be deemed to be an original, and all such counterparts shall together constitute but one and the same instrument. 

16. This Letter Agreement shall be deemed severable, and the invalidity or unenforceability of any term or provision
hereof shall not affect the validity or enforceability of this Letter Agreement or of any other term or provision hereof. Furthermore, in lieu of any such invalid or unenforceable term or provision, the parties hereto intend that there shall be
added as a part of this Letter Agreement a provision as similar in terms to such invalid or unenforceable provision as may be possible and be valid and enforceable. 

17. This Letter Agreement shall be governed by and construed and enforced in accordance with the laws of the State of New
York, without giving effect to conflicts of law principles that would result in the application of the substantive laws of another jurisdiction. The parties hereto (i) all agree that any action, proceeding, claim or dispute arising out of, or
relating in any way to, this Letter Agreement shall be brought and enforced in the courts of New York City, in the State of New York, and irrevocably submit to such jurisdiction and venue, which jurisdiction and venue shall be exclusive and
(ii) waive any objection to such exclusive jurisdiction and venue or that such courts represent an inconvenient forum. 












 18. Any notice, consent or request to be given in connection with any
of the terms or provisions of this Letter Agreement shall be in writing and shall be sent by express mail or similar private courier service, by certified mail (return receipt requested), by hand delivery or facsimile transmission. 

19. This Letter Agreement shall terminate on the earlier of (i) the expiration of the
Lock-up Periods or (ii) the liquidation of the Company; provided, however, that this Letter Agreement shall earlier terminate in the event that the Public Offering is not consummated
and closed by June 30, 2021; provided further that paragraph 4 of this Letter Agreement shall survive such liquidation for a period of six years. 

[Signature Page Follows] 












 
					
	Sincerely,
	
	HAYMAKER SPONSOR III LLC
		
	By:	 	 /s/ Steven J. Heyer

		 	Name:	 	Steven J. heyer
		 	Title:	 	Managing Member
		
	By:	 	 /s/ Steven J. Heyer

		 	Steven J. Heyer
		
	By:	 	 /s/ Andrew J. Heyer

		 	Andrew R. Heyer
		
	By:	 	 /s/ Christopher Bradley

		 	Christopher Bradley
		
	By:	 	 /s/ Joseph M. Tonnos

		 	Joseph M. Tonnos
		
	By:	 	 /s/ Roger Meltzer

		 	Roger Meltzer
		
	By:	 	 /s/ Frederic H. Mayerson

		 	Frederic H. Mayerson
		
	By:	 	 /s/ Stephen W. Powell

		 	Stephen W. Powell


  

					
	Acknowledged and Agreed:
	
	HAYMAKER ACQUISITION CORP. III
		
	By:	 	 /s/ Christopher Bradley

		 	Name:	 	Christopher Bradley
		 	Title:	 	Chief Financial Officer

 [Signature Page to Letter Agreement]