IN8BIO, INC.

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. )

Filed by the Registrant ☒

Filed by a party other than the Registrant ☐

Check the appropriate box:

IN8bio, 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):

350 5th Avenue, Suite 5330

New York, New York 10118

NOTICE OF 2026 ANNUAL MEETING OF STOCKHOLDERS

To Be Held on May 7, 2026 at 9:00 a.m. Eastern Time

Dear Stockholder:

On behalf of our board of directors, we are pleased to invite you to attend the 2026 Annual Meeting of Stockholders of IN8bio, Inc., a Delaware corporation. The Annual Meeting will be held virtually on May 7, 2026 at 9:00 a.m. Eastern Time. Stockholders attending the virtual meeting will be afforded the same rights and opportunities to participate as they would at anin-person meeting. You will be able to attend the Annual Meeting, vote your shares and ask questions during the meeting by visitingwww.proxydocs.com/INAB. You will not be able to attend the meeting in person as the meeting is being held virtually.

Your vote is very important. Whether or not you plan to attend the meeting, we urge you to vote by proxy to ensure your vote is counted.

The Annual Meeting will be held for the following purposes, which are more fully described in the proxy statement accompanying this Notice:

To participate in the Annual Meeting, you will need to register using the control number located on the Notice of Internet Availability of Proxy Materials for the 2026 Annual Meeting of Stockholders, your proxy card or voting instruction form. Additional details regarding access to the Annual Meeting and the business to be conducted at the Annual Meeting are described in the accompanying proxy statement. We recommend that you log in a few minutes early to ensure you are logged in when the Annual Meeting starts.

The record date for the Annual Meeting is the close of business on March 18, 2026. Only stockholders of record at the close of business on that date may vote at the Annual Meeting or any adjournment thereof. A complete list of our stockholders of record will be available for examination on a reasonably accessible electronic network by any stockholder for any purpose germane to the Annual Meeting for a period of 10 days ending on the day before the Annual Meeting date. If you would like to view the list, please email us at ir@in8bio.com.

By Order of the Board of Directors,

Chief Financial Officer and Corporate Secretary

New York, New York

March 26, 2026

You are cordially invited to attend the virtual Annual Meeting. You will not be able to attend the Annual Meeting in person. Whether or not you expect to attend the meeting, please vote over the telephone or the internet as instructed in these materials, or, if you receive a paper proxy card by mail, by completing and returning the proxy mailed to you, as promptly as possible in order to ensure your representation at the meeting. Even if you have voted by proxy, you may still vote online if you attend the meeting. Please note, however, that if your shares are held of record by a broker, bank or other similar organization and you wish to vote during the meeting, you must follow the instructions from such organization.

TABLE OF CONTENTS

WEBSITE REFERENCES

You may also access additional information about IN8bio, Inc. atwww.in8bio.com and investors.in8bio.com. References to our websites throughout this proxy statement are provided for convenience only and the content on our website does not constitute a part of this proxy statement.

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350 5th Avenue, Suite 5330

New York, New York 10118

PROXY STATEMENT

FOR THE 2026 ANNUAL MEETING OF STOCKHOLDERS

To Be Held on May 7, 2026 at 9:00 a.m. Eastern Time