TABLE OF CONTENTS

You should rely only on the information contained in this prospectus or in any free writing prospectus we may specifically authorize to bedelivered or made available to you. Neither we, the selling stockholders nor the underwriters (or any of our or their respective affiliates) have authorized anyone to provide any information other than that contained in this prospectus or in anyfree writing prospectus prepared by or on behalf of us or to which we have referred you. Neither we, the selling stockholders nor the underwriters (or any of our or their respective affiliates) take any responsibility for, and can provide noassurance as to the reliability of, any other information that others may give you. We, the selling stockholders and the underwriters (or any of our or their respective affiliates) are not making an offer to sell these securities in any jurisdictionwhere the offer or sale is not permitted. You should assume that the information appearing in this prospectus or any free writing prospectus is accurate only as of its date, regardless of its time of delivery or the time of any sale of shares of ourClass A common stock. Our business, financial condition, results of operations and prospects may have changed since that date.

Forinvestors outside the United States: We, the selling stockholders and the underwriters have not done anything that would permit this offering or the possession or distribution of this prospectus or any free writing prospectus we may provide to youin connection with this offering in any jurisdiction where action for purpose is required, other than in the United States. Persons outside the United States who come into possession of this prospectus must inform themselves about, and observe anyrestrictions relating to, the offering of the shares of Class A common stock and the distribution of this prospectus outside the United States. See “Underwriting.”

As permitted under the rules of the SEC, this prospectus incorporates important business information about Portillo’s OpCo that iscontained in documents that we file with the SEC, but that is not included in or delivered with this prospectus. You may obtain copies of these documents, without charge, from the website maintained by the SEC at www.sec.gov, as well as fromother sources. See “Where You Can Find More Information” and “Incorporation of Certain Documents by Reference” in this prospectus.

Basis of Presentation

We use a 52- or 53-week fiscal year ending on the Sunday prior to December 31, effective beginning with the first quarter of 2019. In a 52-weekfiscal year, each quarterly period is comprised of 13 weeks. The additional week in a 53-week fiscal year is added to the fourth quarter. We believe the difference in reporting periods does not have a material impact on comparability. Fiscal 2022will consist of 52 weeks and Fiscal 2021, 2020 and 2019 each consisted of 52 weeks.

Trademarks and Trade Names

We own or have the rights to use various trademarks, trade names and service marks, including “Portillo’s” and various logosused in association with our name. Solely for convenience, any trademarks, trade names, service marks or copyrights referred to or used herein are listed without the applicable ©, ® or^™ symbol, but such references or uses are not intended to indicate, in any way, that we, or the applicable owner, will not assert, to the fullest extent under applicable law, our or their, asapplicable, rights to these trademarks, trade names, service marks and copyrights. Other trademarks, trade names, service marks or copyrights of any other company appearing in this prospectus are, to our knowledge, the property of their respectiveowners.

Market and Industry Information

Unless otherwise indicated, market data and industry information used throughout this prospectus is based on management’s knowledge of theindustry and the good faith estimates of management. We also relied, to the extent available, upon management’s review of independent industry surveys and publications and other publicly available information prepared by a number of sources,including Service Management Group (“SMG”), Technomic, The NPD Group, Inc. (“The NPD Group”), and Socialinsider. All of the market data and industry information used in this prospectus involves a number of assumptions andlimitations and you are cautioned not to give undue weight to such estimates. Although we believe that these sources are reliable, neither we nor the underwriters can guarantee the accuracy or completeness of this information and neither we nor theunderwriters have independently verified this information. Additionally, from time to time, these sources may change their input information or methodologies, which may change the related results. While we believe the estimated market position,market opportunity and market size information included in this prospectus is generally reliable, such information, which is derived in part from management’s estimates and beliefs, is inherently uncertain and imprecise. Projections,assumptions and estimates of our future performance and the future performance of the industry in which we operate are necessarily subject to a high degree of uncertainty and risk due to a variety of factors, including those described in“Risk Factors,” “Cautionary Note Regarding Forward-Looking Statements” and elsewhere in this prospectus. These and other factors could cause results to differ materially from those expressed in our estimates andbeliefs and in the estimates prepared by independent parties. In addition, certain market and industry data has been derived from research and “whitespace” modeling prepared for us in 2020 by Forum Analytics, a leading real estateanalytics firm (“Forum Analytics”). We engaged Forum Analytics to prepare a “whitespace” analysis to identify the Company’s potential new unit expansion opportunity in the United States. Additionally, certain informationincluded herein is derived from a consumer survey of NPS scores powered by Dynata LLC (“Dynata”), a global online market research firm, which we commissioned in 2021.

Certain Definitions

As used in thisprospectus, unless otherwise noted or the context requires otherwise:

Non-GAAP Financial Measures

We prepare our consolidated financial statements in accordance with accounting principles generally accepted in the United States of America(“GAAP”). We also supplement our consolidated financial statements with the following non-GAAP financial measures in this prospectus: Adjusted EBITDA, Adjusted EBITDA Margin, Restaurant-LevelAdjusted EBITDA and Restaurant-Level Adjusted EBITDA Margin. See “Summary Historical and Pro Forma Consolidated Financial and Other Data.”

Key Metrics

Same-Restaurant Sales

Same-restaurantsales is the percentage change in year-over-year revenue (excluding gift card breakage) for the comparable restaurant base, which is defined as the number of restaurants open for at least 24

full fiscal months (the “Comparable Restaurant Base”). At the end of fiscal 2021 and at the end of the quarter ended June 26, 2022, there were 61restaurants in the Comparable Restaurant Base. The Comparable Restaurant Base excludes a restaurant that is owned by C&O Chicago, L.L.C. (“C&O”) of which Portillo’s owns 50% of the equity, as described in Note 7 - EquityMethod Investment in the notes to the audited consolidated financial statements included in our Annual Report on Form 10-K for the fiscal year ended December 26, 2021 (the “Annual Report”).

An increase or decrease in same-restaurant sales is the result of changes in restaurant traffic and average guest check. We gather daily salesdata and regularly analyze the restaurant traffic counts and the mix of menu items sold to aid in developing menu pricing, product offerings and promotional strategies designed to produce sustainable same-restaurant sales.

New Restaurant Openings

New restaurantopenings are central to growing our footprint and executing our growth strategy. We have never closed a restaurant in our 59-year history.

Potential new restaurant sites are typically identified and evaluated at least 18 months prior to opening. New restaurant opening datestrigger advance staff recruiting and training, in addition to the relocation of experienced general managers from existing restaurants and other pre-opening expenses.

The total number of new restaurants per year and the timing of new restaurant openings has, and will continue to have, an impact on ourresults of operations.

Average Unit Volume (“AUV”)

AUV is the total revenue (excluding gift card breakage) recognized in the Comparable Restaurant Base, divided by the number of restaurants inthe Comparable Restaurant Base during the period.

An increase or decrease in AUV is the result of changes in restaurant traffic andaverage guest check. We gather daily sales data and regularly analyze the restaurant traffic counts and the mix of menu items sold to aid in developing menu pricing, product offerings and promotional strategies designed to produce sustainable AUV.Historically, when opening restaurants in new markets outside of Chicagoland, we experience higher revenues in the first year of operation with a decline in revenues in the second year. After the second year, we have experienced growth in revenuesin the third year and beyond as the restaurant and brand continue to grow awareness in those markets.

Restaurant-Level Adjusted EBITDA andRestaurant-Level Adjusted EBITDA Margin

Restaurant-Level Adjusted EBITDA is defined as revenue, less restaurant operating expenses,which include cost of goods sold, excluding depreciation and amortization, labor expenses, occupancy expenses and other operating expenses. Restaurant-Level Adjusted EBITDA excludes corporate level expenses, pre-opening expenses and depreciation andamortization on restaurant property and equipment. Restaurant-Level Adjusted EBITDA Margin represents Restaurant-Level Adjusted EBITDA as a percentage of revenue. Restaurant-Level Adjusted EBITDA and Restaurant-Level Adjusted EBITDA Margin are notrequired by, nor presented in accordance with GAAP. Rather, Restaurant-Level Adjusted EBITDA and Restaurant-Level Adjusted EBITDA

Margin are supplemental measures of operating performance of our restaurants. You should be aware that Restaurant-Level Adjusted EBITDA and Restaurant-Level Adjusted EBITDA Margin are notindicative of overall results for the Company, and Restaurant-Level Adjusted EBITDA and Restaurant-Level Adjusted EBITDA Margin do not accrue directly to the benefit of stockholders because of corporate-level expenses excluded from such measures. Inaddition, our calculations thereof may not be comparable to similar measures reported by other companies. We believe that Restaurant-Level Adjusted EBITDA and Restaurant-Level Adjusted EBITDA Margin are important measures to evaluate the performanceand profitability of our restaurants, individually and in the aggregate. Restaurant-Level Adjusted EBITDA and Restaurant-Level Adjusted EBITDA Margin have limitations as analytical tools and should not be considered as a substitute for analysis ofour results as reported under GAAP. For a reconciliation of operating income, the most directly comparable GAAP measure, to Restaurant-Level Adjusted EBITDA, see “Summary Historical and Pro Forma Consolidated Financial and OtherData” herein.

Adjusted EBITDA and Adjusted EBITDA Margin

Adjusted EBITDA represents net income (loss) before depreciation and amortization, interest expense and income taxes, adjusted for the impactof certain non-cash and other items that we do not consider in our evaluation of ongoing core operating performance as identified in the reconciliation of net income (loss), the most directly comparable GAAP measure, to Adjusted EBITDA, included in“Prospectus Summary—Summary Historical and Pro Forma Consolidated Financial and Other Data.” Adjusted EBITDA Margin represents Adjusted EBITDA as a percentage of total revenues. We use Adjusted EBITDA and Adjusted EBITDA Margin(i) to evaluate our operating results and the effectiveness of our business strategies, (ii) internally as benchmarks to compare our performance to that of our competitors and (iii) as factors in evaluating management’s performance whendetermining incentive compensation.

We believe that Adjusted EBITDA and Adjusted EBITDA Margin are important measures of operatingperformance because they eliminate the impact of expenses that do not relate to our core operating performance. Adjusted EBITDA and Adjusted EBITDA Margin are supplemental measures of operating performance and our calculations thereof may not becomparable to similar measures reported by other companies. Adjusted EBITDA and Adjusted EBITDA Margin have important limitations as analytical tools and should not be considered in isolation as substitutes for analysis of our results as reportedunder GAAP.

PROSPECTUS SUMMARY

This summary highlights selected information contained elsewhere in this prospectus or documents incorporated by reference herein, but itdoes not contain all of the information that you should consider before deciding to invest in our Class A common stock. You should read this entire prospectus carefully, including the matters discussed under the headings “Risk Factors,”“Unaudited Pro Forma Financial Information,” and the information that is incorporated in this prospectus by reference to our Annual Report (including, without limitation, matters discussed under the headings “Risk Factors” and“Management’s Discussion and Analysis of Financial Condition and Results of Operations” and in our consolidated financial statements and related notes), our Quarterly Report on Form 10-Q for the quarterly period ended June 26, 2022(the “2022 Q2 Quarterly Report”) (including, without limitation, matters discussed under the heading “Management’s Discussion and Analysis of Financial Condition and Results of Operations” and in our unaudited condensedconsolidated financial statements and related notes) and the other the filings incorporated by reference herein. See “Incorporation of Certain Documents by Reference.” In addition, certain statements in this prospectus includeforward-looking information that is subject to risks and uncertainties. See “Cautionary Note Regarding Forward-Looking Statements.”

Portillo’s: Prepare to Get Obsessed

Portillo’s serves iconic Chicago street food through high-energy, multichannel restaurants designed to ignite the senses and create amemorable dining experience. Since our founding in 1963 in a small trailer which Dick Portillo called “The Dog House,” Portillo’s has grown to become a treasured brand with a passionate (some might say obsessed) nationwide following.Our diverse menu features all-American favorites such as Chicago-style hot dogs and sausages, Italian beef sandwiches, chopped salads, burgers, crinkle-cut french fries,homemade chocolate cake and milkshakes. We create a consumer experience like no other by combining the best attributes of fast casual and quick service concepts with an exciting energy-filled atmosphere and restaurant model capable of generatingtremendous volumes. Nearly all of our restaurants were built with double lane drive-thrus and have been thoughtfully designed with a layout that accommodates a variety of access modes including dine-in,carryout/curbside, delivery and catering in order to quickly and efficiently serve our guests. As of June 26, 2022, we owned and operated 71 Portillo’s restaurants across nine states. According to publicly available information, our restaurantsgenerated higher AUVs than any other public fast casual restaurant concept of $8.2 million in 2021.

No matter how our guests order fromus, our highly productive kitchens and team members consistently serve high-quality food and deliver a memorable guest experience. We believe the combination of our craveable food, multichannel sales model, dedication to operational excellence, anda distinctive culture driven by our team members gives us a competitive advantage and allows us to generate the highest AUVs and

traffic per restaurant among fast casual and quick service restaurants. In 2020, 2021 and the twelve months ended June 26, 2022, the average Portillo’s restaurant generated:

Each Portillo’s location on average served approximately 859,000 guests in 2021 and approximately 847,000 guests in the twelve monthsended June 26, 2022, based on our average per-guest spend of approximately $9.49 for the twelve months ended February 28, 2022 and approximately $9.75 for the twelve months ended June 26, 2022 and our AUVs ofapproximately $8.2 million in 2021 and $8.3 million in the twelve months ended June 26, 2022. Our restaurants are buzzing with the energy and excitement of our team members and guests that bring everyone together, from single diners to large groups,around great food, drinks and fun. Our restaurants have attracted a growing cult-like following that has enabled us to thrive across a variety of suburban and urban trade areas around the country. All of our restaurants are profitable, and we areproud to have never closed a restaurant in our 59-year history.

We believe our unique brand experience, passionate following, and compelling everyday value propositiondrive strong operating results. As a result, we have been able to achieve the following:

During the quarter and two quarters ended June 26, 2022, we experienced unprecedented commodity inflation as well as higher labor expenses,which will continue to have an impact on Restaurant-Level Adjusted EBITDA and our other profitability metrics for the remainder of 2022. For more information, please see “Management’s Discussion and Analysis of Financial Condition andResults of Operations” in our Q2 2022 Quarterly Report, which is incorporated by reference in this prospectus.

($ in Millions)
Restaurants		Total Revenue
Operating Income		Restaurant-Level Adjusted EBITDA (Margin)*
Net Income		Adjusted EBITDA (Margin)*

Our Competitive Strengths

We believe the following strengths separate us from our competitors and serve as the foundation for our continued growth:

Values-Driven, People-Centered Culture. People are the heart of Portillo’s. We hire and train great people who can turntheir obsession into a profession. Our team members are passionate about our food, love our guests, and call their teammates “family.” Our people-centric culture is about working together to deliver an exceptional experience for ourguests, while operating with the fun-loving energy that drives the exciting

atmosphere within our busy restaurants. Our Portillo’s team members bring our brand to life through their commitment to our values:

“Family” – We work together to make everyone feel at home, and we step up when someone needs help

“Greatness” – We are obsessed with being the best and work hard to continuously improve. Our greatness is rooted inQuality, Service, Attitude and Cleanliness (“QSAC”)

“Energy” – We move with urgency and passion, whilemaintaining attention to detail

“Fun” – We entertain our guests, we connect authentically, and we make each othersmile

During the COVID-19 pandemic, we prioritized the health and safety of our team members whoin turn helped our business not only survive but thrive. We chose to not lay off or furlough any team members, and instead invested in them with a focus on cross-training additional skills, which enabled us to increase capacity in our off-premises channels and drive operating efficiencies. We acted quickly to provide paid leave, personal protective equipment and setup a “Wellness Team” to advise on and monitor the well-being of ourteams. Additionally, we provided 100% meal discounts and gift cards to every team member throughout the COVID-19 pandemic and funded bonuses to field managers. We also launched a Company foundation called“The Heart of Portillo’s Fund” to support team members facing challenging personal situations.

We work with each teammember to build a personal development plan and a corresponding training plan to support their professional development at Portillo’s. We view this investment as a fundamental aspect of our company and key to our growth as it enables us todeliver a consistently memorable experience for our guests and build a pipeline of leaders to drive the success of our future restaurant openings.

We are proud that Portillo’s was ranked the #1 restaurant company on America’s 2021 Best Midsized Employers by Forbesmagazine and #99 out of the 500 companies surveyed.

An Iconic and Beloved Brand with Obsessed, Lifelong Fans. Portillo’s captures thehearts, minds and stomachs of its guests with every meal. In the 59 years since Dick Portillo opened his first hot dog stand, Portillo’s has grown to become an iconic restaurant brand with a national following. Our menu features something foreveryone and appeals to a broad demographic that enables our restaurants to thrive across diverse trade areas and generate strong and

balanced volumes across multiple dayparts, weekdays and occasions. Our new restaurant openings draw massive crowds of passionate fans who line up overnight with lines stretching around the block.Additionally, we have received numerous accolades, including recognition as the “#1 Fast Casual Restaurant in the U.S.” by Trip Advisor in 2021.

We have a very engaged and passionate following on social media. As of August 3, 2022, our average Facebook post generates 26x more engagementthan the average industry brand post, while our average Twitter post generates 46x more engagement than the average industry brand post based on industry benchmarks study conducted by Socialinsider in 2022. Many of our fans beg us through socialmedia to bring a Portillo’s restaurant to their city (and we have received similar pleas from mayors), which we believe is indicative of the passion of our guests and the demand for more Portillo’s locations across the country. In asimilar vein, we have operated a direct shipping business for over 20 years, shipping a select menu of our most popular offerings to all 50 states, which provides us with an additional channel to build our national brand presence. In the past fiveyears we have shipped 2.7 million sandwiches (Italian beef, sausages and hot dogs) via our own direct-to-consumer direct shipping channel across all 50 states,creating fans all over the country. Based on a national survey powered by Dynata in July 2021, our nationwide net promoter score exceeded that of many notable fast casual competitors.

Distinctive, Diverse High-Quality Menu. Our menu offers something for everyone. We obsessover each and every ingredient and curate our menu to ensure that each item receives high marks from our guests and meets our rigorous quality standards. Our Italian beef sandwiches feature high-quality beef slow roasted for four hours, thinlysliced, served on freshly baked Turano French bread and dipped in hot gravy with a proprietary blend of spices perfected over 50 years and designed to deliver an amazing flavor. Our Chicago-style hot dogs feature mustard, relish, freshly choppedonion, sliced red ripe tomatoes, a kosher pickle and sport peppers piled high onto a perfectly steamed poppy seed bun, all finished with a few shakes of savory celery salt. Guests also love our craveablecrinkle-cut french fries that are cooked in beef tallow resulting in a perfectly salted, crispy outside with a soft inside. Lastly, for those craving something sweet, our famous homemade fluffy chocolate cakesare baked with love each morning in every restaurant and generously iced with rich chocolate frosting.

Everyone can be satisfied with a visit to one of our restaurants as demonstrated by oursales mix with no single menu category accounting for more than 26% of sales in 2021. As an example of how our guests order across our menu, we sold on average more than $600,000 worth of salad per restaurant in 2021. Menu variety is a majormotivator for guests and the difference with Portillo’s is, no matter what someone is craving, we have something for them.

MenuMix as % of 2021 Sales*

Robust Multichannel Sales Capabilities. Our restaurants are designed to provide speed andconvenience across multiple sales channels including drive-thru, dine-in, carryout/curbside, delivery and catering. We also serve guests outside our footprint through our website for direct shipping. In eachrestaurant, our high-energy, passionate team members deliver exceptional customer service to our guests whether they dine in one of our restaurants or order through the drive-thru where team members personally take and deliver orders car-side. At the onset of the COVID-19 pandemic, we quickly adapted to sales shifts and cross-trained our team members to allow us to significantly increase our drive-thrusales from $3.4 million per restaurant in 2019 to $4.6 million in 2020 and $4.7 million in 2021 and enhance our third-party delivery and self-delivery channels and capabilities. Our app and website, combined with our third-party deliverypartnerships, resulted in approximately 20% of our sales being placed digitally during fiscal 2020 and fiscal 2021 and approximately 21% in the twelve months ended June 26, 2022. Since nearly all of our restaurants were purpose built with a doublelane drive-thru and sizable parking areas to handle our large volumes, we were able to quickly respond to sales shifts without structural changes to our sites. Our ability to execute high sales volumes through our double drive-thrus combined with our robust digital capabilities enabled us to generate approximately 80% of our revenue through these order methods in fiscal 2020 and 74% in fiscal 2021. In a world where customersincreasingly value convenience and optionality, our longstanding multichannel expertise positions Portillo’s to continue to succeed and grow market share.

Average Restaurant Sales by Channel ($ Millions)

Note: Dine-in defined as any order served over the counter inside a restaurant, including dine-in-orders,orders that are “to go”, phone and online orders picked up inside the restaurant. Drive Thru includes all orders serviced outside the restaurant, including drive thru and curbside pickup. Direct-to-consumer shipping sales are not includedin the above. Drive thru, Dine-In and Delivery sales per restaurant includes data from all restaurants open since the beginning of the measurement period.

Energetic Restaurant Atmosphere that Engages the Senses. While our operating model is focused on getting delicious, made-to-order food to our guests quickly, the Portillo’s atmosphere makes the experience even more than a delicious meal. When guests walk into a Portillo’s, theyget an experience completely different than a typical chain restaurant visit. Our restaurants engage all the senses to create a fun, relaxed and memorable occasion.

Our dining areas evoke nostalgia and local influences. No two Portillo’s are alike. Each of our restaurants has its own themeddécor ranging from a 1930’s prohibition motif to a 1950’s jukebox, to a 1960’s hippie bus. The period music ties to the theme, from ragtime to doo wop to disco. No detail is too small, be it lighting, signage or even thestars subtly sparkling on the ceiling. Each restaurant also draws design elements from the community. The layouts create spaces comfortable for individual diners, families, large groups, and even wedding parties.

Beyond the space itself, the energy of a Portillo’s is unique. Our guests can see intoour huge, open kitchens, where their meals are prepared right before their eyes. The smells of burgers broiling, french fries frying, and beef simmering emanate from the kitchen. Each completed meal is announced with a fun rhyme (“Number two,we got you”; “Number seven, welcome to Portillo’s heaven”). But the most important element of

the energy is the enthusiasm of thescores of other guests who are all excited to be there and enjoying their Portillo’s. We want every guest that visits Portillo’s to leave with a memorable experience, a satiated appetite and a desire to return.

An Incredible, Everyday Value Proposition. Portillo’s redefined the fast casual andquick service value propositions by combining high-quality, craveable food served at incredible speed with multichannel convenience all inside a differentiated, energy-filled atmosphere. We do not discount and rarely engage in price promotion of ourproducts. Instead, we provide an exceptional value to our guests every day. We believe the combination of our craveable food made with high-quality ingredients, served fast however you want it, in an engaging atmosphere by our passionate teammembers—all at an affordable per-person spend of approximately $9.75—will continue to sustain and grow our volumes.

Proven Portability and Strong Unit Economics. Our concept is successful across diversemarkets throughout the United States. As of June 26, 2022, we had 71 restaurants open across nine states including Illinois, Arizona, Indiana, Florida, Iowa, Minnesota, Wisconsin, Michigan and California in a variety of urban and suburban tradeareas. Our broadly appealing menu and everyday value caters to a variety of customers and occasions as evidenced by our balanced daypart mix with nearly equal lunch and dinner revenues, as well as a balanced weekday sales mix.

As we increase our brand awareness and guest following outside Chicagoland, we believe our restaurants willbe even better positioned to consistently grow volumes over time, as evidenced by the performance of our Chicagoland restaurants.

Ourteam members’ focus on operational excellence enables our restaurants to drive exceptional throughput, creating substantial volumes and profitability. Restaurants in our Chicagoland market had AUVs of approximately $8.7 million in 2020, $9.6million in 2021 and $9.9 million in the twelve months ended June 26, 2022 and Restaurant-Level Adjusted EBITDA Margins of 31% in 2020, 31% in 2021 and 30% in the twelve months ended June 26, 2022. Restaurants outside of Chicagoland had AUVs ofapproximately $5.6 million in 2020, $5.8 million in 2021 and $5.8 million in the twelve months ended June 26, 2022 and Restaurant-Level Adjusted EBITDA Margins of 25% in 2020, 23% in 2021 and 19% in the twelve months ended June 26,2022. When considering new restaurant locations each year as part of our growth strategy, we target cash-on-cash returns of approximately 25% in our third year ofoperation, which we calculate by dividing our Restaurant-Level Adjusted EBITDA in the third year of operation by our initial investment costs (net of tenant allowances and excluding pre-opening expenses). Weare currently experiencing increased costs associated with building and opening new restaurant locations as a result of inflation.

Visionary Leadership Team. Our iconic brand, values-driven culture and growth strategies are guided by our highly experiencedsenior management team, led by our Chief Executive Officer Michael Osanloo. Mr. Osanloo joined Portillo’s in 2018 and has over 25 years of leadership experience, having previously served as CEO of P.F. Chang’s and EVP of Kraft Foods.In addition to Mr. Osanloo, we have a talented team of industry veterans leading the organization including Chief Financial Officer, Michelle Hook, previously VP of Finance,

FP&A and IR at Domino’s; Chief Operating Officer, Derrick Pratt whose prior experience includes VP-level operations roles at McDonald’s andStarbucks; and Chief Human Resource Officer, Jill Waite, former executive at 24 Hour Fitness and Sephora. Under Mr. Osanloo and the executive team’s leadership, we have made significant investments in our brand, people, culture, systems,and infrastructure. Under Mr. Osanloo and the executive team’s leadership, we have made significant investments in our brand, people, culture, systems, and infrastructure. We believe our experienced management team is a key driver of oursuccess and positions us well for long-term growth.

Our Growth Strategies

We believe we are well-positioned to take advantage of significant growth opportunities due to our values-driven culture, highly-trained andpassionate team members, differentiated brand experience and AUVs which are higher than other public fast casual restaurant concepts according to publicly available information, which drive impressive unit economics. We plan to expand our businessby executing on the following growth strategies:

Expand Our Restaurant Base. We are in the early stages of our nationwide growth with 71locations across nine states as of June 26, 2022. From November 2020 through June 26, 2022, we opened nine new restaurants, including new locations in Illinois, Michigan, Florida, Arizona, Indiana and Wisconsin. Since 2015, we have opened newrestaurants at a compound annual growth rate of approximately 8.7%. Over the long term, we plan to increase our number of restaurants by approximately 10% annually. Our near-term restaurant growth strategy is focused on leveraging our proven uniteconomic model primarily in adjacent and national markets outside Chicagoland with favorable macro-economic tailwinds where we already have a presence. We will also add select new restaurants in the Chicagoland market. We utilize a data drivenapproach with our real estate team to identify optimal sites and curate a high-quality restaurant pipeline. Given our leading volumes and the size of our restaurants, we typically do not compete for real estate with quick service or fast casualconcepts and tend to be a tenant of choice by landlords due to the significant traffic going through our restaurants. People are key to our growth, which is why we have invested in creating professional development plans for our team members toensure a steady flow of Portillo’s trained managers who are ready to staff our new restaurants. Additionally, we have established multiple new restaurant opening teams, which allow us to support our future pace of openings while driving newrestaurant opening success. Based on a whitespace analysis prepared for us by Forum Analytics in 2020, we believe we have a substantial runway for growth with a long-term opportunity to grow to more than 600 restaurants domestically over the next 25years and are well-positioned for global growth in the future. While we are optimistic about our ability to expand our restaurant base, we will continue evaluating the impact of the COVID-19 pandemic, which may continue to disrupt our business andaffect our ability to execute our expansion strategy. For more information, see “Part I. Item 1A. Risk Factors—Risks Related to Our Business, Industry and Growth Strategies—Our financial condition and results of operationshave been and may continue to be adversely affected by the COVID-19 pandemic or future pandemics or disease outbreaks” in our Annual Report which is incorporated by reference herein.

Increase Our Same-Restaurant Sales. We aim to continue delivering anoutstanding value proposition to our guests and enhance our experience to grow our volumes. We believe the following initiatives will drive same-restaurant sales growth:

Leverage Our Infrastructure to Drive Profitability. Our attractive business modelgenerates strong operating margins and cash flow. We constantly focus on restaurant-level operations while ensuring that we do not sacrifice the quality and experience for which we are known. Our AUVs, which were higher in fiscal 2021 than otherpublic fast casual restaurant concepts based on publicly available information, and strong operational focus give us the ability to manage variable costs and leverage our fixed costs. We believe we will continue to grow revenue and system-wideprofitability by executing our growth strategy and leveraging the experience of existing Portillo’s general managers to lead our new restaurants to drive successful and efficient new openings. Our investments to enhance our multichannelcapabilities and drive a frictionless guest order experience are also expected to further leverage our fixed costs. We have made significant investments at the corporate level, which we believe we will leverage in the future, exclusive of theadditional costs of operating as a public company.

Summary of Risk Factors

Our business is subject to numerous risks described in the section titled “Risk Factors” elsewhere in this prospectus and inthe section titled “Part I. Item 1A. Risk Factors” included in our Annual Report, which is incorporated by reference herein. These risks represent challenges to the successful implementation of our strategy and the growth ofour business. Some of these risks are:

Risks Related to this Offering and Ownership of Our Class A Common Stock

Risks Related to Our Business, Industry and Growth Strategies

Risks Related to Our Indebtedness

Risks Related to Our OrganizationalStructure

Risks Related to Intellectual Property, Information Technology, and Data Security

Risks Related toLegal and Regulatory Matters

General Risks

For a discussion of these and other risks you should consider before making an investment in our Class A common stock, see the sectionentitled “Risk Factors.”

ORGANIZATIONAL STRUCTURE

We currently conduct our business through Portillo’s OpCo and its subsidiaries. Portillo’s Inc. is a holding company and its solematerial asset is its ownership interest in Portillo’s OpCo.

In connection with the Reorganization Transactions (as defined herein),the amended and restated limited liability company agreement of Portillo’s OpCo was amended and restated to, among other things, convert all outstanding equity interests (except for those redeemable preferred units which were repaid in full inconnection with the IPO (as defined herein)) into one class of non-voting common units (the “LLC Units”).

On October 25, 2021, the Company closed its initial public offering of 23,310,810 shares of Class A common stock (the “IPO”). Inconnection with the IPO, we entered into the following series of transactions to implement an internal reorganization, which we collectively refer to as the “Reorganization Transactions.”

In connection with this offering, we have entered into an agreementwith the selling stockholders whereby we have agreed to use all of the net proceeds from this offering to purchase LLC Units from certain Continuing Pre-IPO LLC Members and to purchase shares of Class A common stock from the Reorganization Partiesin a “synthetic secondary” transaction, at a price per LLC Unit or share of Class A common stock, as applicable, equal to the public offering price per share of Class A common stock in this offering, less the underwriting discounts andcommissions and any withholding taxes.

Portillo’s Inc. is the sole managing member of Portillo’s OpCo. Because we manage andoperate the business and control the strategic decisions and day-to-day operations of Portillo’s OpCo and because we also have a substantial financial interest inPortillo’s OpCo, we have consolidated the financial results of Portillo’s OpCo, and a portion of our net income will be allocated to the noncontrolling interest to reflect the entitlement of the ContinuingPre-IPO LLC Members to a portion of Portillo’s OpCo’s net income. In addition, because Portillo’s OpCo is under the common control of the Pre-IPO LLCMembers before and after the Reorganization Transactions (both directly and indirectly through their ownership of the Company), we accounted for the Reorganization Transactions as a reorganization of entities under common control and initiallymeasured the interests of the Continuing Pre-IPO LLC Members in the assets and liabilities of Portillo’s OpCo at their carrying amounts as of the date of the completion of the consummation of theReorganization Transactions.

The following diagram depicts our organizational structure immediately following the IPO.This chart is provided for illustrative purposes only and does not purport to represent all legal entities within our organizational structure.

Our corporate structure following the completion of the IPO, asdescribed above, is commonly referred to as an umbrella partnership-C-corporation (or “Up-C”) structure, which is usedby partnerships and limited liability companies when they undertake an initial public offering of their business. Our Up-C structure allows the Continuing Pre-IPO LLCMembers to continue to realize tax benefits associated with owning interests in an entity that is treated as a partnership, or “pass-through” entity, for U.S. federal and applicable state and local income tax purposes following the IPO.One of these benefits is that taxable income of Portillo’s OpCo that is allocated to such owners will be taxed on a flow-through basis and, therefore, will generally not be subject to U.S. federal and applicable state and local income taxes atthe entity level. Additionally, because the LLC Units that the Continuing Pre-IPO LLC Members hold are redeemable or exchangeable for newly issued shares of Class A common stock on a one-for-one basis in accordance with the terms of the Amended LLC Agreement, our “Up-C” structure also provides theContinuing Pre-IPO LLC Members with potential liquidity that holders of nonpublicly traded limited liability companies are not typically afforded. See “Organizational Structure” and“Description of Capital Stock” elsewhere in this prospectus.

We also hold LLC Units, and therefore receive the same benefits as the Continuing Pre-IPO LLC Members with respect to our ownership in an entity treated as a partnership, or “pass-through” entity, for U.S. federal and applicable state and local income tax purposes. The acquisition ofLLC Units pursuant to the IPO (including the repayment of the redeemable preferred units), the Mergers and future taxable redemptions or exchanges by the Continuing Pre-IPO LLC Members for shares of ourClass A common stock or cash are expected to result in favorable tax attributes that will be allocated to us. These tax attributes would not be available to us in the absence of those transactions and are expected to reduce the amount of taxthat we would otherwise be required to pay in the future. In connection with the Reorganization Transactions, we entered into a Tax Receivable Agreement that obligates us to make payments to the TRA Parties in the aggregate generally equal to 85% ofthe applicable cash savings that we actually realize, or in certain circumstances are deemed to realize, as a result of these tax attributes and tax attributes resulting from certain payments made under the Tax Receivable Agreement. We retain thebenefit of the remaining 15% of these tax savings. See “Organizational Structure—Holding Company Structure and the Tax Receivable Agreement” elsewhere in this prospectus.

Under the Amended LLC Agreement, we receive a pro rata share of any distributions, including tax distributions, made by Portillo’s OpCoto its members. Such tax distributions will be calculated based upon an assumed tax rate, which, under certain circumstances, may cause Portillo’s OpCo to make tax distributions that, in the aggregate, exceed the amount of taxes thatPortillo’s OpCo would have paid if it were a similarly situated corporate taxpayer. Funds used by Portillo’s OpCo to satisfy its tax distribution obligations will not be available for reinvestment in our business. See the section entitled“Part I. Item 1A. Risk Factors—Risks Related to Our Organizational Structure” in our Annual Report.

Uponcompletion of this offering and the application of the Company’s net proceeds from this offering:

See “OrganizationalStructure” and “Description of Capital Stock” elsewhere in this prospectus for more information on the rights associated with our common stock and the LLC Units.

Our Sponsor

Berkshire Partners hasinvested more than $16 billion in over 145 private equity investments and as of December 31, 2021, had $23.8 billion in assets under management within Berkshire Private Equity. Berkshire’s current private equity portfolio comprises investmentsacross five sectors — business services & technology, consumer, communications, healthcare, and industrials. The Berkshire Partners team includes more than 65 investment professionals across North America.

In August 2014, we entered into a merger transaction through which we were acquired by funds affiliated with or managed by Berkshire (the“Berkshire Acquisition”).

Following the closing of this offering, funds managed by Berkshire are expected to own (i)approximately 52.7% of the combined voting power of our common stock (or approximately 51.1% of the combined voting power of our common stock, if the underwriters exercise their option to purchase additional shares of Class A common stock in full)and (ii) approximately 52.7% of the economic interest in Portillo’s OpCo (or approximately 51.1% of the economic interest in Portillo’s OpCo, if the underwriters’ option to purchase additional shares is fully exercised). In addition,following the closing of this offering, funds managed by Berkshire are expected to own approximately 38.4% of the LLC Units, or 37.2% if the underwriters’ option to purchase additional shares is fully exercised. As a result, Berkshire will beable to exercise significant voting influence over fundamental and significant corporate matters and transactions. See “Part I. Item 1A. Risk Factors—Risks Relating to This Offering and Ownership of Our Common Stock” inour Annual Report and “Principal Stockholders” elsewhere in this prospectus.

Corporate Information

Portillo’s Inc. was incorporated in Delaware on June 8, 2021. Our principal executive offices are located at 2001 Spring Road, Suite400, Oak Brook, IL 60523, and our telephone number is (630) 954-3773. Our corporate website address is www.portillos.com. Our corporate website and the information contained on, or that can be accessedthrough, the website is not deemed to be incorporated by reference in, and is not considered part of, this prospectus. You should not rely on any such information in making your decision whether to purchase our Class A common stock.

Implications of Being an Emerging Growth Company

As a company with less than $1.07 billion in gross revenue during our last fiscal year, we qualify as an “emerging growthcompany” as defined in the Jumpstart Our Business Startups Act (the “JOBS Act”). An emerging growth company may take advantage of specified reduced reporting and other regulatory requirements for up to five years that are otherwiseapplicable generally to public companies. These provisions include, among other matters:

We will remain an emerging growth company until the last day of the fiscal year following the fifth anniversary of the completion of ourinitial public offering unless, prior to that time, we have more than $1.07 billion in annual gross revenue, have a market value for our common stock held by non-affiliates of more than $700 millionas of the last day of our second fiscal quarter of the fiscal year and a determination is made that we are deemed to be a “large accelerated filer,” as defined in Rule 12b-2 promulgated under theSecurities Exchange Act of 1934, as amended (the “Exchange Act”), or issue more than $1.0 billion of non-convertible debt over a three-year period, whether or not issued in a registeredoffering. We have availed ourselves of the reduced reporting obligations with respect to audited financial statements and related Management’s Discussion and Analysis of Financial Condition and Results of Operations and executive compensationdisclosure in this prospectus and expect to continue to avail ourselves of the reduced reporting obligations available to emerging growth companies in future filings.

In addition, Section 107 of the JOBS Act also provides that an emerging growth company can take advantage of the extended transitionperiod provided in Section 7(a)(2)(B) of the Securities Act of 1933, as amended (the “Securities Act”) for complying with new or revised accounting standards. An emerging growth company can, therefore, delay the adoption of certainaccounting standards until those standards would otherwise apply to private companies. As an emerging growth company, we elected to take advantage of the extended transition period provided in Section 13(a) of the Exchange Act, for complyingwith new or revised accounting standards.

As a result of our decision to avail ourselves of certain provisions of the JOBS Act, theinformation that we provide may be different than what you may receive from other public companies in which you hold an equity interest. In addition, it is possible that some investors will find our Class A common stock less attractive as aresult of our elections, which may cause a less active trading market for our Class A common stock and more volatility in our stock price.

THE OFFERING

stockholders are entitled to vote generally, except as otherwise required by law. See“Description of Capital Stock—Common Stock” elsewhere in this prospectus.

Except as otherwise indicated,the number of shares of our Class A common stock outstanding after this offering:

Unless otherwise indicated or the context otherwise requires, references in this prospectus to the exercise of theunderwriters’ option to purchase additional shares of Class A common stock give effect to the use of the net proceeds therefrom.

SUMMARY HISTORICAL AND PRO FORMA CONSOLIDATED FINANCIAL ANDOTHER DATA

The following tables present the summary historical consolidated financial and other data for Portillo’s Inc. and itssubsidiaries and the summary pro forma consolidated financial and other data for Portillo’s Inc. PHD Group Holdings LLC is the predecessor of the issuer, Portillo’s Inc., for financial reporting purposes. The statements of operations datafor the years ended December 26, 2021, December 27, 2020 and December 29, 2019 and balance sheet data as of December 26, 2021 has been derived from Portillo’s Inc.’s audited consolidated financial statements and the relatednotes thereto incorporated by reference from our Annual Report. The summary historical consolidated financial information as of June 26, 2022 and for the two quarters ended June 26, 2022 and June 27, 2021 have been derived from the unauditedcondensed consolidated financial statements and the related notes thereto incorporated by reference from the 2022 Q2 Quarterly Report. The unaudited condensed consolidated financial statements have been prepared on a basis consistent with ouraudited financial statements and, in our opinion, contain all adjustments, consisting of only normal recurring adjustments, necessary for fair presentation of such financial data. Results for any interim period are not necessarily indicative of theresults that may be expected for the full fiscal year or any future period.

Portillo’s Inc. was formed as a Delaware corporation onJune 8, 2021 and prior to the IPO did not conduct any activities other than those incident to its formation, those in preparation for the Reorganization Transactions and preparation of the IPO. The summary historical financial and other data ofPortillo’s Inc. has not been presented because Portillo’s Inc. was a newly incorporated entity, had no business transactions or activities, assets or liabilities during the periods presented. Immediately following the IPO, Portillo’sInc. became a holding company with its sole material asset being a controlling equity interest in Portillo’s OpCo. Portillo’s Inc., through Portillo’s OpCo, operates and conducts our business. Portillo’s OpCo is considered ourpredecessor for accounting purposes and its consolidated financial statements are our historical financial statements.

The summaryunaudited pro forma combined and consolidated financial data of Portillo’s Inc. presented below have been derived from our unaudited pro forma combined and consolidated financial statements included elsewhere in this prospectus. The unauditedpro forma consolidated statement of operations for the year ended December 26, 2021 gives effect to the pro forma adjustments related to the IPO and the Reorganization Transactions and this offering and the use of net proceeds therefrom as if allsuch transactions had been completed as of December 28, 2020. The unaudited pro forma consolidated statement of operations for the two quarters ended June 26, 2022 presents our consolidated results of income to give pro forma effect to this offeringand use of net proceeds therefrom, as if all such transactions had been completed as of December 27, 2021. The summary unaudited pro forma consolidated balance sheet data as of June 26, 2022 gives effect to this offering and the use of the netproceeds therefrom, each as if they had occurred on June 26, 2022. The summary unaudited combined and consolidated pro forma financial data is presented for illustrative purposes only and is not necessarily indicative of the results of operations orfinancial position that would have occurred if the relevant transactions had been consummated on the dates indicated, nor is it indicative of future operating results or financial position. See “Unaudited Pro Forma Consolidated FinancialInformation” and “Organizational Structure” elsewhere in this prospectus.

Our historical results are notnecessarily indicative of future results of operations. You should read the information set forth below together with “Organizational Structure,” “Unaudited Pro Forma Consolidated Financial Information,”“Capitalization” elsewhere in this prospectus as well as the audited consolidated financial statements and the related notes thereto included in our Annual Report and the unaudited condensed consolidated financial statements and therelated notes thereto included in the 2022 Q2 Quarterly Report.

Management uses Adjusted EBITDA and Adjusted EBITDA Margin (i) to evaluate our operating results and the effectiveness of our businessstrategies, (ii) internally as benchmarks to compare our performance to that of our competitors and (iii) as factors in evaluating management’s performance when determining incentive compensation. The use of Adjusted EBITDA andAdjusted EBITDA Margin as performance measures permit a comparative assessment of our operating performance relative to our performance based on our GAAP results, while isolating the effects of some items that are either non-recurring in nature or vary from period to period without any correlation to our ongoing core operating performance.

Adjusted EBITDA and Adjusted EBITDA Margin or similar non-GAAP measures are frequently used bysecurities analysts, investors and other interested parties as supplemental measures of financial performance within our industry. Management believes that Adjusted EBITDA and Adjusted EBITDA Margin provide investors with additional transparency ofour operations.

Our presentation of Adjusted EBITDA and Adjusted EBITDA Margin should not be construed to imply that our future resultswill be unaffected by these items that are excluded. Adjusted EBITDA and Adjusted EBITDA Margin are supplemental measures of operating performance and our calculations thereof may not be comparable to similar measures reported by other companies.Adjusted EBITDA and Adjusted EBITDA Margin have important limitations as analytical tools, and you should not consider them in isolation or as substitutes for analysis of our results as reported under GAAP. Some of these limitations are:

In evaluating Adjusted EBITDA and Adjusted EBITDA Margin, you shouldbe aware that in the future we may incur expenses similar to those adjusted for in the reconciliation of net income (loss), the most directly comparable GAAP measure to Adjusted EBITDA. We compensate for these limitations by providing specificinformation regarding the GAAP amounts excluded from such non-GAAP financial measures. We further compensate for the limitations in our use of non-GAAP financialmeasures by presenting comparable GAAP measures more prominently.

See below for a reconciliation of net income, the most directlycomparable GAAP measure, to EBITDA, Adjusted EBITDA and Adjusted EBITDA Margin:

Restaurant-Level Adjusted EBITDA and Restaurant-Level Adjusted EBITDA Margin are importantmeasures we use to evaluate the performance and profitability of our restaurants, individually and in the aggregate. Additionally, Restaurant-Level Adjusted EBITDA and Restaurant-Level Adjusted EBITDA Margin or similarnon-GAAP financial measures are frequently used by analysts, investors and other interested parties to evaluate companies in our industry. We believe that Restaurant-Level Adjusted EBITDA and Restaurant-LevelAdjusted EBITDA Margin, when used in conjunction with GAAP financial measures, provide useful information about our operating results, identify operational trends, and allow for greater transparency with respect to key metrics used by us in ourfinancial and operational decision making. We use Restaurant-Level Adjusted EBITDA and Restaurant-Level Adjusted EBITDA Margin to make decisions regarding future spending and other operational decisions. However, you should be aware thatRestaurant-Level Adjusted EBITDA and Restaurant-Level Adjusted EBITDA Margin are financial measures, which are not indicative of overall results for the Company, and Restaurant-Level Adjusted EBITDA and Restaurant-Level Adjusted EBITDA Margin do notaccrue directly to the benefit of stockholders because of corporate-level expenses excluded from such measures. In addition, our calculations of Restaurant-Level Adjusted EBITDA and Restaurant-Level Adjusted EBITDA Margin thereof may not becomparable to similar measures reported by other companies, have limitations as analytical tools and should not be considered as a substitute for analysis of our results as reported under GAAP.

See below for a reconciliation of operating income, the most directly comparable GAAP measure, to Restaurant-Level Adjusted EBITDA.