ALLURION TECHNOLOGIES, INC.

FOR THE

2025 ANNUAL MEETING OF STOCKHOLDERS

TO BE HELD ON DECEMBER 18, 2025

This proxy statement (the “Proxy Statement”) is being furnished in connection with the solicitation by the Board of Directors (the “Board” or “Board of Directors”) of Allurion Technologies, Inc. (“Allurion”, the “Company”, “we”, “us” or “our”) of proxies to be voted at our Annual Meeting of Stockholders (the “Annual Meeting”) to be held on December 18, 2025, at 12:00 p.m. Eastern Time, and at any postponement or adjournment of the Annual Meeting. The Annual Meeting will be a completely virtual meeting conducted via live audio webcast. You will be able to attend the Annual Meeting online and submit your questions during the meeting by visitingwww.virtualshareholdermeeting.com/ALUR2025 and entering your 16-digit control number included on your proxy card or in the instructions that accompanied your proxy materials.

It is expected that the Notice of Meeting, this Proxy Statement and the accompanying proxy card, and our Annual Report on Form 10-K for the fiscal year ended December 31, 2024, as amended (the “2024 Annual Report”), will be mailed on or about November 24, 2025 to our stockholders as of the close of business on the Record Date (as defined below).

Record Date and Outstanding Shares

Holders of record of shares of our common stock, $0.0001 par value per share (the “common stock”), as of the close of business on October 31, 2025 (the “Record Date”), will be entitled to notice of and to vote at the Annual Meeting and any postponement or adjournment thereof.

As of the Record Date, there were 7,770,047 shares of common stock outstanding and entitled to vote at the Annual Meeting. Each share of common stock is entitled to one vote on any matter presented to stockholders at the Annual Meeting. The shares of common stock are our only voting securities.

Proposals

At the Annual Meeting, our stockholders will be asked:

corresponding increase to the number of shares of common stock that may be issued in respect of incentive stock options), (ii) amend the definition of Fully-Diluted Shares Outstanding, (iii) lower the non-employee director compensation limit, and (iv) extend the term of the plan, in each case, as described in such Proposal 3 (the “Plan Amendment Proposal” or “Proposal 3”);

Recommendations of the Board and Proxies

The Board recommends that you vote your shares as indicated below:

If you return a properly completed proxy card, or vote your shares by telephone or Internet, your shares of common stock will be voted on your behalf as you direct. If you return a signed and dated proxy card or otherwise vote without marking voting selections, your shares will be voted in accordance with the recommendations of the Board set forth above.

Any stockholder may revoke a proxy at any time prior to the Annual Meeting by signing and submitting a later-dated proxy or a written notice of revocation to our Secretary, or by granting a subsequent proxy through the Internet or telephone. Stockholders attending the Annual Meeting may also revoke their proxies by voting online at the Annual Meeting. Attendance at the Annual Meeting will not itself be deemed to revoke a proxy unless a stockholder gives affirmative notice at the Annual Meeting that such stockholder intends to revoke the proxy and vote online. If a stockholder’s shares are held in street name, such holder may change or revoke voting instructions by following the specific directions provided by the stockholder’s bank or broker. See “Can I change my vote after I submit my proxy?” below.

Quorum and Adjournment; Abstentions, Votes Withheld and Broker Non-Votes

The presence by remote communication (i.e., online) or by proxy of the holders of a majority in voting power of the shares of common stock issued and outstanding on the Record Date and entitled to vote is required to constitute a quorum at the Annual Meeting.

The stockholders that are present online or represented by proxy at the Annual Meeting may adjourn the meeting from time to time for any reason, regardless of whether a quorum is present. If the Annual Meeting is adjourned to another time, date or place (including an adjournment taken to address a technical failure to convene or continue a meeting using remote communication), notice is not required to be given of the adjourned meeting if the time, place (if any), and the means of remote communication by which stockholders and proxy holders may attend and participate at such adjourned meeting are announced at the Annual Meeting, displayed on the same electronic network used to enable stockholders and proxy holders to participate in the meeting by means of remote communication during the time scheduled for the Annual Meeting, or as set forth in the Notice of Annual Meeting. However, if the adjournment is for more than 30 days from the original meeting date, or if after the adjournment a new record date is fixed for the adjourned meeting, notice of the adjourned meeting and the means of remote communication, if any, will be given to each stockholder of record entitled to vote and each stockholder who, by law or under our organizational documents, is entitled to such notice.

At any adjourned Annual Meeting at which a quorum is present, any business may be transacted that might have been transacted at the Annual Meeting as originally scheduled.

Abstentions, votes withheld and brokernon-votes will count in determining whether a quorum is present at the Annual Meeting and any adjourned meeting. A brokernon-vote occurs if the broker or other nominee who holds shares represented by a proxy has not received instructions with respect to a particular proposal and does not have discretionary authority with respect to such proposal. Under the rules that govern brokers who are voting shares held in street name, brokers have the discretion to vote those shares on routine matters but not onnon-routine matters. Proposals 3, 4, 5, 6, 7 and 8 are considered to be“non-routine” under these rules, such that your broker may not vote your shares on those proposals in the absence of your voting instructions. Conversely, Proposals 1 and 2 are considered to be a “routine” matter under these rules and thus if you do not return voting instructions to your broker by its deadline, your shares may be voted by your broker in its discretion on Proposals 1 and 2.

The votes required, and the treatment of abstentions, votes withheld and brokernon-votes, for each matter to be voted on at the Annual Meeting are set forth in “How many votes are required for the approval of the proposals to be voted upon and how will votes withheld, abstentions and brokernon-votes be treated?” below.

Other Matters

We know of no other business that will be presented at the Annual Meeting. If any other matter properly comes before the stockholders for a vote at the Annual Meeting, the proxy holders named on our proxy card will vote your shares in accordance with their best judgment and consistent with applicable law.

None of our directors or executive officers since the beginning of the last fiscal year, or nominees for director, nor any associate of any of the foregoing, has any substantial interest, direct or indirect, by security holdings or otherwise, in any matter to be acted upon at the Annual Meeting, except as described below.

Certain of our named executive officers hold Eligible Options (as defined below) that would potentially benefit from the Option Repricing (as defined below), in each case subject to the terms and conditions described below under “Specifics of the Option Repricing” in Proposal 4. The following table sets forth, with respect to the named executive officers therein, the number of shares subject to Eligible Options held by such named executive officer and the weighted average exercise price of the Eligible Options, in each case, as of the Record Date.