As filed with the Securities and Exchange Commission on November 5, 2021

Registration No. 333-260396

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

POST-EFFECTIVE AMENDMENT NO. 1

FORM S-8

REGISTRATION STATEMENT

UNDER

THE SECURITIES ACT OF 1933

Portillo’s Inc.

(Exact name of registrant as specified in its charter)

Portillo’s, Inc. 2021 Equity Incentive Plan

(Full title of the plan)

Susan B. Shelton

General Counsel and Secretary

2001 Spring Road, Suite 400

Oak Brook, IL 60523

(630) 354-3773

(Name, Address, Including Zip Code, and Telephone Number, Including Area Code, of Agent for Service of Process)

Copies to:

Alexander D. Lynch

Merritt S. Johnson

Weil, Gotshal & Manges LLP

767 Fifth Avenue

New York, NY 10153

(212) 310-8000 (Phone)

(212) 310-8007 (Fax)

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company,” and “emerging growth company” in Rule 12b-2 of the Exchange Act.

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 7(a)(2)(B) of the Securities Act.  ☐

EXPLANATORY NOTE

This Post-Effective Amendment No. 1 relates to the Registrant’s Registration Statement on Form S-8 (File No. 333-260396), initially filed by the Registrant on October 21, 2021 (the “Registration Statement”). The Registrant is filing this Post-Effective Amendment No. 1 for the sole purpose of correcting the allocation of all shares of the Registrant’s Class A common stock registered pursuant to the Registration Statement to the Portillo’s Inc. 2021 Equity Incentive Plan (the “2021 Plan”). The Registration Statement incorrectly indicated that 6,416,865 shares of Class A common stock would be allocated and available for issuance under the 2014 Equity Incentive Plan (the “2014 Plan”). However, in connection with the Registrant’s initial public offering, each outstanding option previously granted under the 2014 Plan was substituted for an option to purchase a number of shares of the Registrant’s Class A common stock under the 2021 Plan. Therefore, all 13,564,914 shares of Class A common stock registered pursuant to the Registration Statement should be allocated to the 2021 Plan. The total number of shares registered is unchanged and the requisite filing fee has been fully paid.

This Post-Effective Amendment No. 1 does not modify any provision of Part I or Part II of the Registration Statement other than as set forth below.

PART II

INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

The exhibits to this Registration Statement are listed in the Exhibit Index below and are incorporated by reference herein.

Exhibit Index

SIGNATURES

Pursuant to the requirements of the Securities Act of 1933, the registrant certifies that it has reasonable grounds to believe that it meets all of the requirements for filing on Form S-8 and has duly caused this Post-Effective Amendment No. 1 to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of Oak Brook, State of Illinois, on November 5, 2021.

Pursuant to the requirements of the Securities Act of 1933, this Registration Statement has been signed by the following persons in the capacities indicated on November 5, 2021.

Exhibit 5.1

767 Fifth Avenue New York, NY 10153-0119 +1 212 310 8000 tel +1 212 310 8007 fax

November 5, 2021

Portillo’s Inc.

2001 Spring Road, Suite 400

Oak Brook, IL 60523

Ladies and Gentlemen:

We have acted as counsel to Portillo’s Inc., a Delaware corporation (the “Company”), in connection with the preparation and filing with the Securities and Exchange Commission of the Company’s Post-Effective Amendment No. 1 (the “Post-Effective Amendment”) to the Registration Statement on Form S-8 (the “Registration Statement”), under the Securities Act of 1933, as amended (the “Securities Act”), relating to the registration by the Company of up to 6,416,865 shares of the Company’s Class A common stock which may be issued pursuant to the Portillo’s Inc. 2021 Equity Incentive Plan (the “2021 Equity Plan”), which is incorporated by reference as Exhibit 99.1 to the Registration Statement, par value $0.01 per share, of the Company (the “Shares”).

In so acting, we have examined originals or copies (certified or otherwise identified to our satisfaction) of (i) the Amended and Restated Certificate of Incorporation of the Company; (ii) the Amended and Restated Bylaws of the Company; (iii) the 2021 Equity Plan; (iv) the Registration Statement; (v) the Post-Effective Amendment; and (vi) such corporate records, agreements, documents and other instruments, and such certificates or comparable documents of public officials and of officers and representatives of the Company, and have made such inquiries of such officers and representatives, as we have deemed relevant and necessary as a basis for the opinion hereinafter set forth.

In such examination, we have assumed the genuineness of all signatures, the legal capacity of all natural persons, the authenticity of all documents submitted to us as originals, the conformity to original documents of all documents submitted to us as certified, conformed or photostatic copies, and the authenticity of the originals of such latter documents. As to all questions of fact material to this opinion that have not been independently established, we have relied upon certificates or comparable documents of officers and representatives of the Company.

Based on the foregoing, and subject to the qualifications stated herein, we are of the opinion that the Shares, when issued and delivered upon the receipt of consideration constituting lawful consideration under Delaware law in accordance with the 2021 Equity Plan, will be validly issued, fully paid and non-assessable.

The opinions expressed herein is limited to the corporate laws of the State of Delaware, and we express no opinion as to the effect on the matters covered by this letter of the laws of any other jurisdiction.

November 5, 2021 Page 2

We hereby consent to the use of this letter as an exhibit to the Registration Statement and to any and all references to our firm in the Registration Statement. In giving such consent we do not hereby admit that we are in the category of persons whose consent is required under Section 7 of the Securities Act or the rules and regulations of the Securities and Exchange Commission.

Very truly yours,

/s/ Weil, Gotshal & Manges LLP

Exhibit 23.1

CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

We consent to the incorporation by reference in this Registration Statement No. 333-260396 on Form S-8 of our report dated September 27, 2021, relating to the balance sheet of Portillo’s Inc., appearing in Registration Statement No. 333-259810 on Form S-1 of Portillo’s Inc.

/s/ Deloitte & Touche LLP

Chicago, Illinois

November 5, 2021

Exhibit 23.2

CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

We consent to the incorporation by reference in this Registration Statement No. 333-260396 on Form S-8 of our report dated July 16, 2021 (August 27, 2021, as to the effects of the restatement discussed in Note 2), relating to the financial statements of PHD Group Holdings LLC, appearing in Registration Statement No. 333-259810 on Form S-1 of Portillo’s Inc.

/s/ Deloitte & Touche LLP

Chicago, Illinois

November 5, 2021