UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 14A

Proxy Statement Pursuant to Section 14(a) of

the Securities Exchange Act of 1934 (Amendment No. )

LOGICBIO THERAPEUTICS, INC.

(Name of Registrant as Specified In Its Charter)

(Name of Person(s) Filing Proxy Statement, if other than the Registrant)

Payment of Filing Fee (Check the appropriate box):

(1) Amount Previously Paid:

LogicBio Therapeutics, Inc.

99 Erie St.65 Hayden Avenue, Floor 2

Cambridge,Lexington, MA 0213902421

NOTICE OF 20192020 ANNUAL MEETING OF STOCKHOLDERS

The 20192020 Annual Meeting of Stockholders (the “Annual Meeting”) of LogicBio Therapeutics, Inc. (the “Company” or “LogicBio”) will be held on June 25, 2019,19, 2020, at 1:9:00 p.m. EDTa.m. E.T. at Ropes & Gray LLP, 800 Boylston St., Boston, Massachusetts, for the purpose of considering and voting on the following two company-sponsored proposals:

We will also consider and act upon any other matters that properly come before the Annual Meeting or any adjournment or postponement thereof.

These proposals are more fully described in the Proxy Statement accompanying this Notice. This notice, the proxy statement and our Annual Report onForm 10-K for the year ended December 31, 2019 (the “Annual Report”) can be accessed at the following website: www.envisionreports.com/LOGC.

Our Board of Directors recommends that you vote “for” each nominee for Class III director (proposal no. 1) and “for” ratification of the proposed independent registered public accounting firm (proposal no. 2).

April 29, 2019,22, 2020 has been fixed as the record date for the determination of the stockholders entitled to notice of and to vote at the Annual Meeting or any adjournments thereof. A list of stockholders as of the record date will be available for stockholder inspection at the headquarters of the Company, 99 Erie Street, Cambridge,65 Hayden Avenue, Floor 2, Lexington, MA 02139,02421, during ordinary business hours, from June 14, 20199, 2020 to the date of the Annual Meeting. The list will also be available for inspection at the Annual Meeting.

Your vote is important. Whether or not you expect to attend the Annual Meeting, we urge you to vote your shares by following the instructions in the Important Notice Regarding the Availability of Proxy Materials that you previously received and submit your proxy by the Internet or telephone or by signing, dating and returning the proxy card included in these materials in order to ensure that your vote is recorded. If you choose to attend the Annual Meeting, you may still vote your shares in person, even if you have previously voted or returned your proxy by any of the methods described in our proxy statement. If your shares are held in a bank or brokerage account, please refer to the materials provided by your bank or broker for voting instructions. If you need assistance voting your shares, please call Matthias JafféBryan Yoon, Esq., Corporate Secretary of the Company, at (617)245-0399.

All stockholders are extended a cordial invitation to attend the Annual Meeting. We look forward to seeing you. Thank you for your ongoing support of and interest in LogicBio Therapeutics, Inc.

* We intend to hold our Annual Meeting in person. However, we are actively monitoring thecoronavirus (COVID-19) situation and are sensitive to the public health and travel concerns our stockholders may have and the protocols that federal, state, and local governments may impose. In the event it is not possible or advisable to hold our Annual Meeting in person, we will announce alternative arrangements for the meeting as promptly as practicable, which may include holding the meeting solely by means of remote communication. If we take this step, we will announce the alternative arrangements via press release, which will be filed as Definitive Additional Materials with the SEC, and details on how to participate will be available at www.envisionreports.com/LOGC.

TABLE OF CONTENTS

i

LogicBio Therapeutics, Inc.

99 Erie St.65 Hayden Avenue, Floor 2

Cambridge,Lexington, MA 0213902421

PROXY STATEMENT FOR 20192020 ANNUAL MEETING OF STOCKHOLDERS

To Be Held on Tuesday,Friday, June 25, 201919, 2020 at 1:9:00 p.m. EDTa.m. ET

This proxy statement, along with the accompanying Notice of 20192020 Annual Meeting of Stockholders, contains information about the 20192020 Annual Meeting of Stockholders of LogicBio Therapeutics, Inc., including any adjournments or postponements of the meeting, which we refer to as the Annual Meeting. We are holding the Annual Meeting at 1:9:00 p.m. EDTa.m. ET at Ropes & Gray LLP, 800 Boylston St., Boston, Massachusetts.

In this proxy statement, we refer to LogicBio Therapeutics, Inc. as “LogicBio,” “the Company,” “we” and “us.”

This proxy statement relates to the solicitation of proxies by our Board of Directors for use at the Annual Meeting.

On or about April 29, 2019,2020, we made available this proxy statement and the attached Notice of 20192020 Annual Meeting of Stockholders to all stockholders entitled to vote at the Annual Meeting, and we began sending the proxy card and the Important Notice Regarding the Availability of Proxy Materials to all stockholders entitled to vote at the Annual Meeting. Although not part of this proxy statement, we have also made available with this proxy statement our Annual Report on Form10-K for the fiscal year ended December 31, 2018,2019, containing our financial statements for the fiscal year ended December 31, 2018.2019.

IMPORTANT NOTICE REGARDING THE AVAILABILITY OF PROXY MATERIALS

FOR THE STOCKHOLDER MEETING TO BE HELD ON JUNE 25, 201919, 2020

This proxy statement and our Annual Report on Form10-K are available for viewing, printing and downloading at www.proxyvote.com.www.envisionreports.com/LOGC. To view these materials, please have your16-digit15-digit control number(s) available that appears on your proxy card.

Additionally, you can find a copy of our Annual Report on Form10-K on the website of the Securities and Exchange Commission, or the SEC, at www.sec.gov, or in the “SEC Filings” tab of the “Investors” section of our website at www.logicbio.com. You may also obtain a printed copy of our Annual Report, free of charge, by sending a written request to: LogicBio Therapeutics, Inc., 99 Erie St., Cambridge,65 Hayden Avenue, Floor 2, Lexington, MA 02139,02421, Attention: Corporate Secretary. Exhibits, if any, will be provided upon written request and payment of an appropriate processing fee.

EXPLANATORY NOTE

We are an “emerging growth company,” as defined in the Jumpstart Our Business Startups Act of 2012, or the JOBS Act, and therefore we are permitted and intend to rely on exemptions from certain disclosure requirements that are applicable to other public companies that are not emerging growth companies. These exemptions include reduced disclosure obligations regarding executive compensation. In addition, as an emerging growth company, we are not required to conduct votes seeking approval, on an advisory basis, of the compensation of our named executive officers or the frequency with which such votes must be conducted.

We could be an emerging growth company through 2023, although circumstances could cause us to lose that status earlier, including if the market value of our common stock held bynon-affiliates exceeds $700.0 million as of any June 30 before that time or if we have total annual gross revenue of $1.07 billion or more during any fiscal year before that time, in which cases we would no longer be an emerging growth company as of the following December 31 or, if we issue more than $1.00 billion innon-convertible debt during any three-year period before that time, we would cease to be an emerging growth company immediately.

IMPORTANT INFORMATION ABOUT THE ANNUAL MEETING AND VOTING

Why is the Company Soliciting My Proxy?

The Board of Directors of LogicBio Therapeutics, Inc. is soliciting your proxy to vote at the 20192020 Annual Meeting of Stockholders to be held at 1:9:00 p.m. EDTa.m. ET on June 25, 2019,19, 2020, at Ropes & Gray LLP, 800 Boylston St., Boston, Massachusetts, including any adjournments or postponements of the meeting, which we refer to as the Annual Meeting. This proxy statement along with the accompanying Notice of 20192020 Annual Meeting of Stockholders summarizes the purposes of the meeting and the information you need to know to vote at the Annual Meeting.

We have made available to you on the Internet or have sent you this proxy statement, the Notice of 20192020 Annual Meeting of Stockholders, the proxy card and a copy of our Annual Report on Form10-K for the fiscal year ended December 31, 20182019 because you owned shares of LogicBio common stock on the record date.

We intend to hold our Annual Meeting in person. However, we are actively monitoring thecoronavirus (COVID-19) situation and are sensitive to the public health and travel concerns our stockholders may have and the protocols that federal, state, and local governments may impose. In the event it is not possible or advisable to hold our Annual Meeting in person, we will announce alternative arrangements for the meeting as promptly as practicable, which may include holding the meeting solely by means of remote communication. If we take this step, we will announce the alternative arrangements via press release, which will be filed as Definitive Additional Materials with the SEC, and details on how to participate will be available at www.envisionreports.com/LOGC.

When were this proxy statement and the accompanying materials sent to stockholders?

On or about April 29, 2019,2020, we began sending the Important Notice Regarding the Availability of Proxy Materials to all stockholders entitled to vote at the Annual Meeting.

When is the record date for the Annual Meeting?

The Company’s Board of Directors has fixed the record date for the Annual Meeting as of the close of business on April 29, 2019.22, 2020. Only stockholders who owned our common stock at the close of business on April 29, 201922, 2020 are entitled to vote at the Annual Meeting.

How many votes can be cast by all stockholders?

A total of 23,073,11423,323,336 shares of common stock of the Company were outstanding on April 29, 201922, 2020 and are entitled to be voted at the meeting. Each share of common stock is entitled to one vote on each matter.

What is the difference between being a stockholder of record and a beneficial owner?

Many of our stockholders hold their shares through stockbrokers, banks, or other nominees, rather than directly in their own names. As summarized below, there are some differences between being a stockholder of record and a beneficial owner.

What are the Board’s recommendations on how to vote my shares?

The Board of Directors recommends a vote:

Who pays the cost for soliciting proxies?

LogicBio will bear the cost of solicitation of proxies. This includes the charges and expenses of brokerage firms and others for forwarding solicitation material to beneficial owners of our outstanding common stock. LogicBio may solicit proxies by mail, personal interview, telephone or via the Internet through its officers, directors and other management employees, who will receive no additional compensation for such services.

May my broker vote for me?

Under the rules of the Financial Industry Regulatory Authority, ifIf your broker holds your shares in street name, the broker may vote your shares on certain routine matters even if it does not receive instructions from you. At the Annual Meeting, your broker may, without instructions from you, vote on Proposal 2, which is considered a routine matter, but not on any of the other proposals.

If there are insufficient votes to approve these proposals, your proxy may be voted by the persons named in the proxy card to adjourn the Annual Meeting in order to solicit additional proxies in favor of the approval of such proposal(s). If the Annual Meeting is adjourned or postponed for any purpose, at any subsequent reconvening of the meeting, your proxy will be voted in the same manner as it would have been voted at the original convening of the Annual Meeting unless you withdraw or revoke your proxy.

Could other matters be decided at the Annual Meeting?

LogicBio does not know of any other matters that may be presented for action at the Annual Meeting. Should any other business come before the meeting, the persons named on the enclosed proxy will have discretionary authority to vote the shares represented by such proxies. If you hold shares through a broker, bank or other nominee as described above, they will not be able to vote your shares on any other business that comes before the Annual Meeting unless they receive instructions from you with respect to such matter.

What happens if the meeting is postponed or adjourned?

YourSubject to the provisions of our bylaws, your proxy may be voted at the postponed or adjourned meeting. You will still be able to change your proxy until it is voted.

SECURITY OWNERSHIP OF CERTAIN BENEFICIAL OWNERS AND MANAGEMENT

The following table sets forth certain information as of March 31, 2019April 10, 2020 (unless otherwise specified), with respect to the beneficial ownership of our common stock by each person who is known to own beneficially more than 5% of the outstanding shares of common stock, each person currently serving as a director, each nominee for director, each named executive officer (as set forth in the Summary Compensation Table below) and all directors and executive officers as a group. The number of shares beneficially owned by each entity or person is determined in accordance with the rules of the SEC, and the information is not necessarily indicative of beneficial ownership for any other purpose. Under such rules, beneficial ownership includes any shares over which the individual has sole or shared voting power or investment power as well as any shares that the individual has the right to acquire within 60 days of March 31, 2019April 10, 2020 through the exercise of any stock options, warrants or other rights. Except as otherwise indicated, and subject to applicable common property laws, the persons in the table have sole voting and investment power with respect to all shares of common stock held by that person.

Shares of common stock subject to options, warrants or other rights that are now exercisable or are exercisable within 60 days after March 31, 2019April 10, 2020 are considered outstanding for purposes of computing the percentage ownership of the persons holding these options, warrants or other rights but are not to be considered outstanding for the purpose of computing the percentage ownership of any other person. As of March 31, 2019,April 10, 2020, there were 23,073,11423,302,669 shares of common stock outstanding. Unless otherwise indicated, the address for each beneficial owner is c/o LogicBio Therapeutics, Inc., 99 Erie St., Cambridge,65 Hayden Avenue, Floor 2, Lexington, MA 02139.02421.

MANAGEMENT AND CORPORATE GOVERNANCE

BOARD COMPOSITION AND STRUCTURE

Our amended and restated certificate of incorporation, or our certificate of incorporation, states that the Board of Directors shall consist of not fewer than three and not more than fifteen members, and the precise number of directors shall be fixed by a resolution of the Board of Directors. Each director holds office until his or her successor is duly elected and qualified or until his or her death, resignation or removal. Our certificate of incorporation provides that our directors may be removed only for cause by the affirmative vote of the holders of at least seventy-five percent (75%) of the voting power of the outstanding shares of capital stock of the Company entitled to vote generally in the election of directors, voting together as a single class, at a meeting of the stockholders called for that purpose. Any vacancy in the Board of Directors, including a vacancy that results from an increase in the number of directors, may be filled by a vote of the majority of the directors then in office.

Our certificate of incorporation provides that the Board of Directors is divided into three classes of directors, with the classes as nearly equal in number as possible. Each of our directors identified below serves in the class indicated. Subject to any earlier resignation or removal in accordance with the terms of our certificate of incorporation and amended and restated bylaws, or bylaws, our Class III directors, if elected at the Annual Meeting, will serve until the 20222023 annual meeting of stockholders, our Class II directors will serve until the 2020 annual meeting of stockholders and our Class III directors will serve until the 2021 annual meeting of stockholders and our Class I directors will serve until the 2022 annual meeting of stockholders. Any additional directorships resulting from an increase in the number of directors will be apportioned by the Board of Directors among the three classes.

The Board of Directors is currently comprised of nineeight members. Below is a list of the names, ages as of March 31, 20192020 and classification of the individuals who currently serve as our directors.

DIRECTOR BIOGRAPHIES

Information concerning our directors is set forth below. The biographical description of each director includes the specific experience, qualifications, attributes and skills that led to the Board of Directors’ conclusion at the time of filing of this proxy statement that each person listed below should serve as a director.

CLASSDIRECTOR NOMINEES (CLASS II DIRECTORS)

Leon Chen, Ph.D. has served as a member of our board of directors since January 2016. Dr. Chen is a partner at The Column Group, a healthcare investment firm, where he has been employed since October 2019. Prior to joining The Column Group, Dr. Chen was a venture partner at OriMed Advisors, a healthcare investment firm, where he had been employed since June 2013. Dr. Chen currently serves on the boards of several privately held life sciences companies. He has a B.A. in biochemistry from U.C. Berkeley, a Ph.D. in molecular pharmacology from Stanford and an M.B.A. from the Stanford Graduate School of Business. We believe that Dr. Chen’s venture capital experience, especially his experience investing in life sciences companies, provides him with the qualifications and skills to serve as a director.

Daniel O’Connell, M.D., Ph.D. has served as a member of our board of directors since June 2017. Since April 2020, Dr. O’Connell has been the executive director, corporate development at Bristol-Myers Squibb Company. From October 2016 until July 2019, Dr. O’Connell served as an investment director of Arix Bioscience, a healthcare and life science company. Previously, from March 2012 to August 2016, Dr. O’Connell served as an associate at OrbiMed Advisors, a healthcare investment firm. He formerly served as a director of PreciThera, Inc., a privately held company, from July 2017 until July 2019.

Dr. O’Connell earned his S.B. in both chemistry and mathematics from MIT and an M.D. and Ph.D. from Tufts University. We believe Dr. O’Connell’s investment experience in the healthcare space provides him with the qualifications and skills to serve as a director.

DIRECTORS WITH TERMS EXPIRING IN 2021 (CLASS III DIRECTORS)

Frederic Chereau has served as our President and Chief Executive Officer since April 2016. Prior to joining LogicBio, Mr. Chereau served as the President and Chief Operating Officer of aTyr Pharma Inc. from February 2014 to July 2015. Before that, he worked at Shire Pharmaceuticals, a biopharmaceutical company, serving as Senior Vice President—Global Franchise Lead, Angioedema, from September 2012 to December 2013. Before the acquisition of Pervasis Therapeutics by Shire, Mr. Chereau served as its Chief Executive Officer and President since October 2008. Before Pervasis, Mr. Chereau worked at Genzyme from 1999 to 2008, where he held various positions within the organization in Europe and in the United States, culminating in his position as Vice President and General Manager of the Cardiovascular Business Unit. Previously, he held various sales and marketing roles in a medical device company in France. Mr. Chereau serves on the board of directors of Dynacure, a biotechnology company dedicated to the development of new treatments for patients affected by centronuclear myopathies, and on the strategic advisory board of La Rochelle Business School in France. He holds a bachelor’s degree in physics from Paris University, a master’s degree from ESC La Rochelle and an M.B.A. from INSEAD. We believe that Mr. Chereau is qualified to serve as a member of our board based on his experience in the biotechnology industry, as well as his insight as our President and Chief Executive Officer.

Richard Moscicki, M.D. has served as a member of our board of directors since October 2018. Dr. Moscicki is currently the Executive Vice President for Science and Regulatory Advocacy and the Chief Medical Officer at Pharmaceutical Research and Manufacturers of America, a position he has held since October 2017. Previously, from March 2013 to October 2017, he served as Deputy Center Director for Science Operations for the U.S. Food and Drug Administration’s Center for Drug Evaluation and Research. Since June 2018, Dr. Moscicki has served as a director of Akcea Therapeutics, Inc. (Nasdaq: AKCA), where he is also a member of the nominating and governance committee and the compensation committee. He has also served as a director of KSQ Therapeutics, Inc. since September 2018. He received a B.S. and an M.D. from Northwestern University. We believe Dr. Moscicki is qualified to serve as a member of our board based on his extensive clinical and regulatory experience in the pharmaceutical industry.

Michael Wyzga has served as a member of our board of directors since September 2018. Mr. Wyzga is currently the President of MSW Consulting, Inc., a private company focused on strategic biotechnology consulting, a position he has held since November 2013. Prior to that, Mr. Wyzga served as President and Chief Executive Officer and a member of the Board of Directors of Radius Health, Inc., a publicly traded biopharmaceutical company, from 2011 until November 2013. Prior to that, Mr. Wyzga served in various senior management positions at Genzyme Corporation. Mr. Wyzga joined Genzyme in February 1998 and most recently served as Executive Vice President, Finance from 2003 until 2011 and as chief financial officer from 1999 until 2011. Mr. Wyzga has served as anon-executive director and a member of the audit committee of Mereo BioPharma Group plc (Nasdaq: MREO) since April 2019 and served as a director of OncoMed Pharmaceuticals, Inc. from February 2013 until its merger with Mereo in April 2019. Since February 2015, Mr. Wyzga has also served as a director of Exact Sciences Corporation (Nasdaq: EXAS), where he is also a member of the audit and compensation committees. Mr. Wyzga has served as the chairman of the board of X4 Pharmaceuticals, Inc. (Nasdaq: XFOR) since 2018 and has served as the chairman of the board of GenSight Biologics, a biotechnology company listed in Euronext Paris, since 2017. Mr. Wyzga also previously served as a director of Akebia Therapeutics, Inc. (Nasdaq: AKBA), a publicly traded biotechnology company, from February 2014 until December 2018, Idenix Pharmaceuticals, Inc., a publicly traded biotechnology company that was acquired by Merck (NYSE: MRK) in August 2014, where he also served as the chair of the audit committee and a member of the compensation committee, and as a member of the Supervisory Board of Prosensa Holding B.V., a publicly traded biopharmaceutical company, from June 2014 until its acquisition by BioMarin Falcon B.V. (Nasdaq: BMRN) in December 2014. He received an M.B.A. from Providence College and a B.S. from Suffolk University. We believe Mr. Wyzga’s extensive experience in the biotechnology space, and his financial experience, provide him with the qualifications and skills to serve as a director.

DIRECTORS WITH TERMS EXPIRING IN 2022 (CLASS I DIRECTOR NOMINEESDIRECTORS)

Erez Chimovits has served as a member of our board of directors since January 2016. Mr. Chimovits is a senior managing director with OrbiMed, a healthcare investment firm, where he has been employed since 2010. He has more than fourteen years of operational experience, including ten years of senior managerial experience in public companies. Prior to joining OrbiMed, he was the Chief Executive Officer of NasVax Ltd. Previously, Mr. Chimovits spent more than seven years with

Compugen, as President, Compugen USA Inc. and Executive Vice President, Commercial Operations. He currently serves as a member of the board of directors of Novus Therapeutics, Inc. and BiomX, Inc. Mr. Chimovits earned his M.B.A., M.Sc. in Microbiology and his B.Sc. from Tel Aviv University. We believe Mr. Chimovits is qualified to serve on our board of directors due to his vast operational and managerial experience in the biopharmaceutical industry, much of which took place in public companies.

and Corporate Governance Committee does not have a written policy regarding stockholder nominations, but has determined that it is the practice of the committee to consider candidates proposed by stockholders if made in accordance with our bylaws.

Board Meetings and Attendance

The Board of Directors held ninefive meetings during the year ended December 31, 2018.2019. Each of the directors attended at least seventy-five percent (75%) of the meetings of the Board of Directors and the committees of the Board of Directors on which he or she served during the year ended December 31, 20182019 (in each case, which were held during the period for which he or she was a director and/or a member of the applicable committee and excluding any meetings in which a director was an interested party).

Thenon-employee directors met in executive session during each of the regularly scheduled Board of Directors meetings during the year ended December 31, 2018.2019.

BOARD COMMITTEES

The Board of Directors has a standing Audit, Compensation and Nominating and Corporate Governance Committee, each of which is comprised solely of independent directors and is described more fully below. Each committee operates pursuant to a written charter, and each reviews and assesses the adequacy of its charter periodically and submits its charter to the Board of Directors for approval. The charter for each committee is available on our website (www.logicbio.com) under the “Investors—Corporate Governance” section.

The following table describes which directors serve on each of the Board of Directors’ committees.

Nominating and Corporate Governance Committee

Our Nominating and Corporate Governance Committee is composed of Tomer KarivMark Enyedy and Richard Moscicki, M.D., with Dr. Moscicki serving as Chair of the committee. Mr. Kariv was a member of our Nominating and Corporate Governance Committee throughout 2019 and until his resignation from our Board of Directors on March 12, 2020. Mr. Enyedy joined our Nominating and Corporate Governance Committee upon his appointment to our Board of Directors becoming effective on March 17, 2020. The Board of Directors has determined that each member of the Nominating and Corporate Governance Committee is “independent” as defined under the applicable listing standards of Nasdaq. The Nominating and Corporate Governance Committee’s responsibilities include:

Compensation Committee

Our Compensation Committee is composed of Leon Chen, Ph.D., Erez Chimovits and Daniel O’Connell, M.D., Ph.D., with Dr. Chen serving as Chair of the committee. The Board of Directors has determined that each member of the Compensation Committee is “independent” as defined under the applicable listing standards of Nasdaq and meets the independence criteria set forth in Rule10C-1. The Compensation Committee’s responsibilities include:

compensation advisors as compensation consultants to the Compensation Committee has not created any conflicts of interest, and that Pay GovernanceArnosti Consulting is independent pursuant to the independence standards set forth in the Nasdaq listing standards promulgated pursuant to Section 10C of the Exchange Act.

Delegation of Authority and The Role of Management

The Compensation Committee may delegate to subcommittees, consisting of one or more members of the Compensation Committee, any of the responsibilities of the full committee.committee and may delegate any of its responsibilities to the extent permitted by applicable law to the CEO and/or other senior officers, except that compensation actions affecting the CEO or other senior officers may not be so delegated to any senior officer.

OurA subset of our executive officers, including our Chief Executive Officer, participate in general sessions of our Compensation Committee. Management does not participate in executive sessions of our Compensation Committee. At the request of our Compensation Committee, our Chief Executive Officer makes compensation-related recommendations to the Compensation Committee with respect to annual base salary, target bonus opportunities and long-term incentive award grants for the namedour executive officers (other than himself). No member of the management team, including our Chief Executive Officer, has a role in determining his or her own compensation.

Compensation Committee Interlocks and Insider Participation

None of the members of our Compensation Committee has at any time during the prior three years been one of our officers or employees. None of our executive officers currently serves, or in the past fiscal year has served, as a member of the board of directors or compensation committee of any entity that has one or more executive officers serving on our Board of Directors or Compensation Committee. For a description of transactions between us and members of our Compensation Committee and affiliates of such members, please see “Certain Relationships and Related Party Transactions.”

Risks Related to Compensation Practices and Policies

The Compensation Committee maintains apay-for-performance compensation philosophy, but also recognizes that providing certain types of compensation incentives may inadvertently motivate individuals to act in ways that could be detrimental to the Company in order to maximize personal compensation. To minimizemitigate such risk, the Compensation Committee reviews at least annually the overall structure and components of our compensation program and, with respect to our executive officers, the levels of executive compensation under such program. The Compensation Committee has reviewed our compensation program and has determinedbelieves that it does not encourage inappropriate actions or risk taking and is not reasonably likely to have a material adverse effect on our business. In addition, we do not believe that the mix andor design of the components of our executive compensation program encourage managementencourages our executive officers to assume excessive risks. We believe that our compensation program, current business process and planning cycle fosters the behaviors and controls that would mitigate the potential for adverse risk caused by the action of our executives, including the following:

post on our website any amendment to, or waiver under, a provision of the Code of Business Conduct and Ethics that applies to our directors and certain of our executive officers within four business days following the date of such amendment or waiver.

A copy of the Corporate Governance Guidelines may also be accessed free of charge by visiting our website at www.logicbio.com and going to the “Corporate Governance” tab under the “Investors” section, or by requesting a copy in writing from our Corporate Secretary at our Cambridge,Lexington, Massachusetts office.

EXECUTIVE OFFICERS

Below is a list of the names, ages as of March 31, 20192020 and positions, and a brief account of the business experience of the individuals who serve as our executive officers.

EXECUTIVE OFFICER BIOGRAPHIES

Biographical information for Frederic Chereau, our Chief Executive Officer and President, is included herein under “Director Biographies—Directors with Terms Expiring in 2021 (Class III Directors).”

Dean Falb, Ph.D. has served as our Chief Scientific Officer since May 2018. Before joining LogicBio, from October 2013 to May 2018, Dr. Falb served as founder and chief technology officer of Synlogic, Inc., a biotechnology company. Before that, he was an entrepreneur in residence with Atlas Ventures, a venture capital firm, from 2012 to 2014. He also held senior research positions at Praecis Pharmaceuticals and Stryker Regenerative Medicine, and was a founding scientist at Millennium Pharmaceuticals in 1993. Dr. Falb holds a B.S. in chemistry from Purdue University and a Ph.D. in biochemistry and molecular biology from Harvard University.

Matthias Jaffé has served as our Chief Financial Officer since September 2017. Prior to joining LogicBio, from October 2012 to July 2017, Mr. Jaffé served as Chief Financial Officer of Constellation Pharmaceuticals, a biopharmaceutical company. Before that, he served as Chief Financial Officer of Zafgen, Pervasis Therapeutics and Alantos Pharmaceuticals. He holds an M.S. in biology from MIT and an M.B.A. from INSEAD.

Tom WiltonBryan Yoon, Esq. has served as our Chief BusinessAdministrative Officer, General Counsel and Corporate Secretary since September 2017. From April 2015November 2019. Mr. Yoon was most recently the General Counsel and Secretary at Nightstar Therapeutics plc, a gene therapy company focused on inherited retinal diseases, from November 2017 until its acquisition by Biogen in June 2019. At Nightstar, he was responsible for the legal, compliance and intellectual property functions, in addition to Septemberleading all human resources activities, through a period of significant growth. Prior to Nightstar, Mr. Yoon worked at Intercept Pharmaceuticals, Inc., a leading biopharmaceutical company focusing on nonviral liver diseases, from January 2013 until November 2017, Mr. Wiltonwhere he most recently served as Chief Business Officer for the UniversitySenior Vice President—Legal Affairs and Secretary. Previously, Mr. Yoon worked at Mintz, Levin, Cohn, Ferris, Glovsky and Popeo P.C. and Simpson Thacher & Bartlett LLP, where he advised clients, including a number of Pennsylvania’s Gene Therapy Program. Before that, from September 2010 to April 2015,life sciences companies, on a variety of corporate and other legal matters. Mr. Wilton served as a senior director at GlaxoSmithKline, a pharmaceutical company. HeYoon holds a B.S.B.A. in medical scienceEconomics and an M.Eng. in Operations Research and Industrial Engineering from Cornell University. He received his J.D. from the University of London, a master’s degree from the University of Leeds in health systems research and a master’s degree from Brunel University London in strategic technology management.

EXECUTIVE COMPENSATION

Introduction

This section provides an overview of our compensation arrangements with our principal executive officer and our next two most highly compensated executive officers in respect of their service to us in 2018.2019. These individuals, who we refer to as our “named executive officers,” are:

*Ms. Poole resigned from her position as Chief Operation Officer and terminated employment effective as of March 31, 2019.

Summary Compensation Table

The following table sets forth the compensation awarded to, earned by, or paid to our named executive officers in respect of their service to us during 20182019 and, if applicable, 2017.2018.

Narrative Disclosure to Summary Compensation Table

Agreements with Our Named Executive Officers

Mr.Messrs. Chereau and Yoon and Dr. FalbHuttner are each party to an amended and restated employment agreement with us that sets forth the terms and conditions of their employment with us and are also each party to a confidential information and invention assignment agreement with us. Prior to her resignation in March 2019, Ms. Poole was also party to an amended and restated employment agreement and a confidential information and invention assignment agreement with us. The material terms of these agreements are summarized below. As used in the summary below, the terms “cause,” “disability,” “good reason” and “change of control” have the meanings set forth in the applicable agreement.

Sandra Poole. We entered into an employment agreement with Ms. Poole, pursuant to which she agreed to serve as our Chief Operating Officer beginning on April 30, 2018. The employment agreement was amended and restated in connection with our initial public offering. Under the amended and restated agreement, Ms. Poole was entitled to receive an annual base salary of $390,000 per year and was eligible to receive an annual bonus with a target annual bonus of 35% of her annual base salary. If Ms. Poole’s employment was terminated by us other than for cause and other than due to her death or disability or if Ms. Poole resigned for good reason, she would have been entitled to the same severance benefits described above for Dr. Falb. Ms. Poole did not receive any severance payments or benefits in connection with her resignation in March 2019.

Restrictive Covenants. Each of our named executive officers has entered into a confidential information and invention assignment agreement, which contains covenants regarding confidential information and invention assignment, as well as a covenant not to solicit our employees during the named executive officer’s employment with us and for one year thereafter.

Base Salaries

TheMr. Chereau’s base salaries for our named executive officers are set forthsalary was increased to $510,000 per year in their employment agreements with us, as described above. In connection with our initial public offering in October 2018 and was not increased in 2019. The base salaries for Mr. Yoon and Dr. Huttner were established in connection with their commencing employment with us in 2019 at $380,000 per year and $360,000 per year, respectively.

Effective as of January 1, 2020, Mr. Chereau’s annual base salary was increased from $385,000 to $510,000, Dr. Falb’s$526,800, Mr. Yoon’s annual base salary was increased from $325,000 to $340,000,$392,500 and Ms. Poole’sDr. Huttner’s annual base salary was increased from $350,000 to $390,000.$371,900. In April 2020, in light of theCOVID-19 pandemic, Mr. Chereau agreed to decrease his annual base salary to $421,440, Mr. Yoon agreed to decrease his annual base salary to $314,000 and Dr. Huttner agreed to become a part-time employee and decrease his annual base salary to $185,950.

Annual Bonuses

Each of our named executive officers is eligible to receive an annual bonus, with the target amount of such bonus, expressed as a percentage of the named executive officer’s annual base salary, set forth in the named executive officer’s employment agreement with us, as described above. In connection with our initial public offering, Dr. Falb’s target annual bonus was increased from 30% to 35% of his annual base salary and Ms. Poole’s target annual bonus was increased from 30% to 35% of her annual base salary. Mr. Chereau’s target annual bonus was not adjusted in connection with our initial public offering.

For 2018,2019, each of our named executive officers received a bonus based on the achievement of corporate objectives that were determined by our board of directors,Compensation Committee, including financial and product development-related objectives related to the

no portion of the payments or benefits would constitute a “parachute payment” or (ii) the full amount of such payments and benefits, whichever results in the payment of the greatergreater after-tax amount to the named executive officer.

Employee Benefits

We currently provide broad-based health and welfare benefits, including health, dental, vision, life and short- and long-term disability insurance, that are available to all of our full-time employees, including our named executive officers. In addition, we maintain a SIMPLE IRA retirement plan for all of our full-time employees. In 2019 and 2018, we contributed an amount equal to 2% of each participating employee’s eligible employee’s compensation to this plan. Our named executive officers are eligible to participate in these plans on the same basis as other eligible employees.

Outstanding Equity Awards at FiscalFiscal Year-End Table

The following table sets forth information concerning the equity awards held by our named executive officers as of December 31, 2018.2019.

DIRECTOR COMPENSATION

Under ournon-employee director compensation policy in effect during 2019, which our Board of Directors adopted in connection with our initial public offering, eachnon-employee director receivesreceived an annual cash retainer for service to our boardBoard of directorsDirectors and an additional annual cash retainer for service on any committee of our boardBoard of directorsDirectors or for serving as the chair of our boardBoard of directorsDirectors or any of its committees, in each case, prorated for partial years of service, as follows:

In connection with our initial public offering, eachOur Board of Directors elected to maintain the annual cash retainer at the same levels for 2020.

Ournon-employee director was granted an option to purchase shares of our common stock intended to have a grant date fair value of approximately $175,000compensation policy in effect during 2019 provided that vests in equal annual installments over three years or upon an earlier change in control, subject to thenon-employee director’s continued service through the applicable vesting date.

Eachanynon-employee director who is first elected to our boardBoard of directors following the completion of our initial public offeringDirectors will be granted an option to purchase shares of our common stock having a grant date fair value of $175,000, such$175,000. For 2020, ournon-employee director compensation policy provides that anynon-employee director first elected to our Board of Directors will be granted an option to purchase 20,000 shares of our common stock. Option granted to anon-employee director who is first elected to our Board of Directors will vest in equal annual installments over three years or upon an earlier change in control, subject to thenon-employee director’s continued service through the applicable vesting date.

CommencingThenon-employee director compensation policy in 2019 also provides that each annualnon-employee director who was not first elected withinhas served on our Board of Directors for more than six months at thesix-month period immediately preceding time of the first meeting of our boardBoard of directorsDirectors following the annual meeting of our stockholders will be granted at such board meeting an option to purchase shares of our common stock having a grant date fair value of $87,500,$87,500. For 2020, anynon-employee director who has served on our Board of Directors for more than six months at the time of the annual meeting of stockholders will be granted an option to purchase 10,000 shares of our common stock on the date our annual meeting of stockholders is held. Any such option granted to anon-employee director will vest in full on the earlier of the first anniversary of the date of grant or the date of the following annual meeting of our stockholders, with prorated accelerated vesting upon a change in control prior to such date, in each case, subject to thenon-employee director’s continued service through the applicable vesting date. On December 19, 2019, each of ournon-employee directors received an option to purchase 10,869 shares of our common stock at a price per share of $12.65. These options vest 100% on the earlier of July 15, 2020 or the 2020 Annual Meeting of Stockholders, or upon an earlier change in control, subject to thenon-employee director’s continued service through the applicable vesting date.

All options granted to ournon-employee directors have a per share exercise price at least equal to the fair market value of a share of our common stock on the date of grant and expire not later than ten years after the date of grant. All cash retainers are paid quarterly, in arrears, or upon the earlier resignation or removal of thenon-employee director. For the calendar quarter during which anon-employee director is newly elected or appointed to our initial public offering was completed,board, all cash retainers wereare prorated based on the number of calendar days served by suchnon-employee director following the completion of our initial public offering.his or her election or appointment.

Eachnon-employee director is also entitled to reimbursement for reasonable travel and other expenses incurred in connection with attending meetings of our board of directors and any committee on which he or she serves.

The following table sets forth a summary of the compensation we paid to ourour non-employee directors directors during 2018.2019. Mr. Chereau, our President and Chief Executive Officer, receives no compensation for his services as a director and, as a result, is not included in the table below. The compensation received by Mr. Chereau in 20182019 for his services as an employee is described in the “Summary Compensation Table” above and the accompanying narrative description.

Consulting Agreement with Dr. Kay

We entered into a consulting agreement with Dr. Kay on December 18, 2015, pursuant to which he agreed to provide services to us ona project-by-project basis. Dr. Kay received $67,500 per year in consulting fees under this agreement. We entered into a new consulting agreement with Dr. Kay on April 1, 2018, pursuant to which he agreed to continue to provide consulting services to us onan as-requested basis. Under this agreement, Dr. Kay is entitled to receive $67,500 per year in consulting fees and an additional $5,000 for every Scientific Advisory Board meeting that he attends in person. Dr. Kay also agreed to certain covenants regarding confidential information and invention assignment, as well as a covenant not to solicit our employees during the term of the agreement and for one year thereafter.

AUDIT COMMITTEE REPORT

The Audit Committee has reviewed the audited consolidated financial statements of LogicBio for the year ended December 31, 2019, and has discussed these statements with management and Deloitte & Touche LLP, or Deloitte, the Company’s independent registered public accounting firm. LogicBio management is responsible for preparing the Company’s financial statements and for maintaining an adequate system of disclosure controls and procedures and internal control over financial reporting for that purpose. The independent registered public accounting firm audits the annual consolidated financial statements prepared by management, expresses an opinion as to whether those consolidated financial statements present fairly the consolidated financial position, results of operations and cash flows of LogicBio in conformity with U.S. generally accepted accounting principles and discusses any issues it believes should be raised with us. The Audit Committee is responsible for providing independent, objective oversight of the Company’s accounting functions and internal controls. The Audit Committee also reviewed management’s report on its assessment of the effectiveness of the Company’s internal control over financial reporting as of December 31, 2019.

The Audit Committee also received from, and discussed with, Deloitte the written disclosures and other communications that the Company’s independent registered public accounting firm is required to provide to the Audit Committee, including the matters required to be discussed by the applicable requirements of the Public Company Accounting Oversight Board, or PCAOB, and the Securities and Exchange Commission.

Deloitte also provided the Audit Committee with the written disclosures and the letter required by Rule 3526 of the PCAOB. PCAOB Rule 3526 requires independent registered public accounting firms annually to disclose in writing all relationships that in their professional opinion may reasonably be thought to bear on independence, to confirm their perceived independence and engage in a discussion of independence. The Audit Committee has reviewed this disclosure and has discussed with Deloitte its independence from LogicBio.

Based on its discussions with management and Deloitte, and its review of the representations and information provided by management and Deloitte, the Audit Committee recommended to the Board of Directors that the audited consolidated financial statements be included in the LogicBio Annual Report on Form10-K for the year ended December 31, 2019, for filing with the Securities and Exchange Commission.

The Audit Committee of LogicBio Therapeutics, Inc.

Michael Wyzga, Chair

Leon Chen

Mark Enyedy

Principal Accountant Fees and Services

We regularly review the services and fees of our independent registered public accounting firm. These services and fees are also reviewed by the Audit Committee on an annual basis. The aggregate fees billed for the fiscal years ended December 31, 2018 and 2019 for each of the following categories of services are as follows (in thousands):

Audit Fees. Consistfees in 2018 include fees, including out of aggregate fees for professional services providedpocket expenses, in connection with the annual audit of our consolidated financial statements, the review of our quarterly condensed consolidated financial statements, consultations on accounting matters directly related to the audit, and comfort letters, consents and assistance with and review of documents filed with the SEC.

Audit-Related Fees. Consist of aggregate fees for accounting consultations and other services that were reasonably related to the performance of audits or reviews of our consolidated financial statements and were not reported above under “Audit Fees.”

Tax Fees. Consist of aggregate fees for tax compliance, tax advice and tax planning services including the review and preparation of our federal and state income tax returns.

All Other Fees. Consist of aggregate fees billed for products and services provided by the independent registered public accounting firm other than those disclosed above.

The Audit Committeepre-approved all services performed since thepre-approval policy was adopted.

Policy on Audit CommitteePre-Approval of Audit and PermissibleNon-Audit Services of Independent Registered Public Accounting Firm

The Audit Committeepre-approves all auditing services, internal control related services and permittednon-audit services (including the fees and terms thereof) to be performed by Deloitte, subject to thede minimis exception fornon-audit services that are approved by the Audit Committee prior to the completion of an audit. The Audit Committee may delegatepre-approval authority to one or more members of the Audit Committee consistent with applicable law and listing standards, provided that the decisions of such Audit Committee member or members must be communicated to the Audit Committee at its next scheduled meeting.

CERTAIN RELATIONSHIPS AND RELATED PARTY TRANSACTIONS

Except as described below, there have been no transactions since January 1, 2019 in which we were a party, the amount involved exceeded or will exceed $120,000 and in which any related person had a direct or indirect material interest.

Indemnification Agreements and Directors’ and Officers’ Liability Insurance

We have entered into indemnification agreements with each of our directors and executive officers. We also maintain a general liability insurance policy, which covers certain liabilities of directors and officers of the Company arising out of claims based on acts or omissions in their capacities as directors or officers.

Related Person Transactions Policy

We have adopted a related person transactions policy that governs the review and approval of related person transactions. Pursuant to this policy, if we want to enter into a transaction with any of our executive officers, directors, director nominees, beneficial owners of more than 5% of our common stock or immediate family members of any of the foregoing, the Audit Committee will review all of the material facts of the proposed transaction and either approve or disapprove of such transaction. If advance approval by the Audit Committee of such a transaction is not feasible, such matter will be reviewed and, if the Audit Committee determines it to be appropriate, ratified at the next regularly scheduled meeting of the Audit Committee. In determining whether to approve or ratify a related person transaction, the Audit Committee will take into account, among other factors it deems appropriate, whether such transaction is on terms no less favorable than terms generally available to an unaffiliated third party under the same or similar circumstances and the extent of the related person’s interest in the transaction.

PROPOSAL NO. 1—ELECTION OF DIRECTORS

In accordance with the Company’s certificate of incorporation and bylaws, the Board of Directors is divided into three classes. The members of each class are elected to serve a three-year term with the term of office of each class ending in successive years. Leon Chen and Daniel O’Connell are the Class II directors whose terms expire at the 2020 Annual Meeting of Stockholders. Drs. Chen and O’Connell have each been nominated for and have agreed to stand for election to the Board of Directors to serve as a Class II director of the Company for three years and until his successor is duly elected and qualified or until his earlier death, resignation or removal.

Our bylaws provide for a majority voting standard for the election of directors in an uncontested election. Accordingly, a director nominee will be elected at the Annual Meeting only if the votes properly cast FOR his election exceed the votes properly cast AGAINST his election.

It is intended that, unless you give contrary instructions, shares represented by proxies will be voted FOR the election of the nominees listed. LogicBio has no reason to believe that the nominees will be unable to serve. In the event that the nominees are unexpectedly not available to serve, proxies may be voted for another person nominated as a substitute by the Board of Directors, or the Board of Directors may determine that no directors are to be elected at the Annual Meeting. Information relating to the nominees for election as directors and for each continuing director, including his period of service as a director of LogicBio, principal occupation and other biographical material is shown earlier in this proxy statement.

THE BOARD OF DIRECTORS UNANIMOUSLY RECOMMENDS THAT YOU VOTE “FOR” THE NOMINEES FOR CLASS II DIRECTORS.

PROPOSAL NO. 2—RATIFICATION OF SELECTION OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

We are asking our stockholders to ratify the Audit Committee’s selection of Deloitte & Touche LLP, or Deloitte, as our independent registered public accounting firm for the fiscal year ending December 31, 2020. Deloitte has served as our independent registered public accounting firm since 2019.

The Audit Committee annually reviews the independent registered public accounting firm’s independence, including reviewing all relationships between the independent registered public accounting firm and us and any disclosed relationships or services that may impact the objectivity and independence of the independent registered public accounting firm, and the independent registered public accounting firm’s performance. Although ratification is not required by our bylaws or otherwise, the Board of Directors is submitting the selection of Deloitte to our stockholders for ratification as a matter of good corporate practice. If the selection is not ratified, the Audit Committee will consider whether it is appropriate to select another independent registered public accounting firm. Even if the selection is ratified, the Audit Committee in its discretion may select a different registered public accounting firm at any time during the year if the committee determines that such a change would be in the best interests of the Company and our stockholders.

We expect that a representative of Deloitte will attend the Annual Meeting and the representative will have an opportunity to make a statement if he or she so chooses. The representative will also be available to respond to appropriate questions from stockholders.

THE BOARD OF DIRECTORS UNANIMOUSLY RECOMMENDS THAT YOU VOTE “FOR” THE RATIFICATION OF THE SELECTION OF DELOITTE & TOUCHE LLP AS THE COMPANY’S INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM FOR THE FISCAL YEAR ENDING DECEMBER 31, 2020.

GENERAL MATTERS

Availability of Certain Documents

A copy of our 20182019 Annual Report on Form10-K has been posted on the Company’s website (www.logicbio.com) along with this proxy statement. Upon written request, we will mail, without charge, a copy of our 20182019 Annual Report on Form10-K, excluding exhibits. Please send a written request to our Corporate Secretary at:

LogicBio Therapeutics, Inc.

99 Erie St.65 Hayden Avenue, Floor 2

Cambridge,Lexington, MA 0213902421

Attention: Corporate Secretary

Phone: (617)245-0399

SEC rules concerning the delivery of annual disclosure documents allow us or your broker to send a single notice or, if applicable, a single set of our proxy materials to any household at which two or more of our stockholders reside, if we or your broker believe that the stockholders are members of the same family, unless we have received contrary instructions from one or more of the stockholders. This practice, referred to as “householding,” benefits both you and us. It reduces the volume of duplicate information received at your household and helps to reduce our expenses. The rule applies to our notices, annual reports, proxy statements and information statements.

We will undertake to deliver promptly, upon written or oral request, a separate copy to a stockholder at a shared address to which a single copy of the notice or proxy materials was delivered. You may make a written or oral request by sending a notification to our Corporate Secretary at the address or telephone number above, providing your name, your shared address, and the address to which we should direct the additional copy of the notice or proxy materials. Multiple stockholders sharing an address who have received one copy of a mailing and would prefer us to mail each stockholder a separate copy of future mailings should contact us at our principal executive offices. Additionally, if current stockholders with a shared address received multiple copies of a mailing and would prefer us to mail one copy of future mailings to stockholders at the shared address, notification of that request may also be made through our principal executive offices. Stockholders who participate in householding will continue to have access to and utilize separate proxy voting instructions.

Stockholder Proposals and Nominations

Requirements for Stockholder Proposals to be Considered for Inclusion in our Proxy Materials. To be considered for inclusion in next year’s proxy statement, stockholder proposals pursuant to Rule14a-8 under the Exchange Act must be received by our Corporate Secretary at our principal executive offices no later than the close of business on December 31, 2019,30, 2020, which is 120 days prior to the date that is one year from April 29, 2020, the date this year’s mailing date of April 29, 2019.proxy statement was released to shareholders.

Requirements for Stockholder Proposals or Director Nominations to be Brought Before an Annual Meeting. Our bylaws provide that, for stockholder nominations to the Board of Directors or other proposals to be considered at an annual meeting, the stockholder must have given timely notice thereof in writing to the Corporate Secretary at LogicBio Therapeutics, Inc., 99 Erie St., Cambridge,65 Hayden Avenue, Floor 2, Lexington, MA 02139. The nominating and corporate governance committee does not have a written policy regarding stockholder nominations, but has determined that it is the practice of the committee to consider candidates proposed by stockholders if made in accordance with our bylaws.02421. To be timely for the 20202021 annual meeting, although not included in the proxy statement, the stockholder’s notice must be delivered to or mailed and received by us not earlier than the close of business on the 120th day nor later than the close of business on the 90th day prior to the anniversary date of the prior year’s annual meeting, except that if the annual meeting is set for a date that is not within 30 days before or after such anniversary date, we must receive the notice not later than the close of business on the tenth day following the day on which we first provide notice or public disclosure of the date of the meeting. Assuming the date of our 20192020 annual meeting is not so advanced or delayed, stockholders who wish to make a proposal at the 20202021 annual meeting must notify us no earlier than February 26, 202019, 2021 and no later than March 27, 2020.21, 2021. Such notice must provide the information required by our bylaws with respect to each matter the stockholder proposes to bring before the 20202021 annual meeting.

Contacting the Board of Directors

Stockholders wishing to communicate with the Board of Directors may do so by writing to the Board or to thenon-employee members of the Board as a group, at:

LogicBio Therapeutics, Inc.

99 Erie St.65 Hayden Avenue, Floor 2

Cambridge,Lexington, MA 0213902421

Attention: Corporate Secretary

The communication must prominently display the legend “BOARD COMMUNICATION” in order to indicate to the Corporate Secretary that it is a communication for the Board. Upon receiving such a communication, the Corporate Secretary will promptly forward the communication to the relevant individual or group to which it is addressed. Certain items that are unrelated to the Board’s duties and responsibilities may be excluded. The Corporate Secretary will not forward any communication determined in his good faith belief to be frivolous, unduly hostile, threatening, illegal or similarly unsuitable.

Other Matters

As of the date of this proxy statement, the Board of Directors does not intend to present any matters other than those described herein at the Annual Meeting and is unaware of any matters to be presented by other parties. If other matters are properly brought before the meeting for action by the stockholders, proxies will be voted in accordance with the recommendation of the Board or, in the absence of such a recommendation, in accordance with the judgment of the proxy holder.

Small steps make an impact. Help the environment by consenting to receive electronic delivery, sign up at www.envisionreports.com/LOGC Notice of 2020 Annual Meeting of Stockholders Proxy Solicited by Board of Directors for Annual Meeting June 19, 2020 Frederic Chereau, Bryan Yoon, or either of them, each with the power of substitution, are hereby authorized to represent and vote the shares of the undersigned, with all the powers which the undersigned would possess if personally present, at the Annual Meeting of Stockholders of LogicBio Therapeutics, Inc. to be held on June 19, 2020 or at any postponement or adjournment thereof. Shares represented by this proxy will be voted by the stockholder. If no such directions are indicated, the Proxies will have authority to vote FOR the election of the nominees listed in Proposal 1 and FOR Proposal 2. In their discretion, the Proxies are authorized to vote upon such other business as may properly come before the meeting. (Items to be voted appear on reverse side) Proxy LogicBio Therapeutics, Inc. q IF VOTING BY MAIL, SIGN, DETACH AND RETURN THE BOTTOM PORTION IN THE ENCLOSED ENVELOPE. Q Change of Address Please print new address below. Comments Please print your comments below. C Non-Voting Items Important Notice Regardingnotice regarding the AvailabilityInternet availability of Proxy Materialsproxy materials for the Annual Meeting:

Meeting of Stockholders. The Form 10-K, Noticematerial is available at: www.envisionreports.com/LOGC 2020 Annual Meeting Admission Ticket 2020 Annual Meeting of Stockholders of LogicBio Therapeutics, Inc. June 19, 2020, 9:00 a.m. ET Ropes & Proxy Statement are availableGray LLP 800 Boylston Street, Boston, Massachusetts 02199 Upon arrival, please present this admission ticket and photo identification atwww.proxyvote.com the registration desk.

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