StepStone Group Inc.

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, DC 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:

STEPSTONE GROUP 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 all boxes that apply):

StepStone Group Inc.

277 Park Avenue, 45 th Floor

New York, NY 10172

NOTICE OF ANNUAL MEETING OF STOCKHOLDERS

September 8, 2026

1:00 p.m. Eastern Time

www.proxydocs.com/STEP

To Our Stockholders:

We are pleased to invite you to attend the 2026 Annual Meeting of Stockholders of StepStone Group Inc. (“StepStone,” the “Company,” “we,” “us” or “our”) on Tuesday, September 8, 2026 at 1:00 p.m., Eastern Time, online via live audio webcast by visitingwww.proxydocs.com/STEP (the “Annual Meeting”) for the following purposes:

1. To elect the seven director nominees named in the proxy statement, each to serve for aone-year term and until his or her successor has been duly elected and qualified, or until his or her earlier death, resignation, removal, retirement or disqualification (“Proposal 1”);

2. To ratify the appointment of Ernst & Young LLP as the Company’s independent registered public accounting firm for the fiscal year ending March 31, 2027 (“Proposal 2”);

3. To approve, on anon-binding and advisory basis, the compensation of our named executive officers (“Proposal 3” or“Say-on-Pay”); and

4. To transact any other business that may be properly presented at the Annual Meeting or any adjournment or postponement thereof.

The Company’s board of directors has determined to continue holding the Annual Meeting virtually. We believe that this is the right choice for StepStone as it provides expanded stockholder access regardless of the location of the Annual Meeting or resources available to stockholders, may improve communications, and allows the participants to attend the Annual Meeting conveniently from any location.

Stockholders of record as of the close of business on July 14, 2026 are entitled to notice of, and, as described in this paragraph, to vote at, the Annual Meeting, or any adjournment or postponement thereof. Holders of our Class A common stock and holders of our Class B common stock are entitled to one vote for each share held of record on all matters submitted to a vote of stockholders. Holders of our Class A common stock and Class B common stock will vote together as a single class on all matters presented to our stockholders for their vote or approval, except as otherwise required by applicable law.

As permitted by the Securities and Exchange Commission (“SEC”), we are providing access to our proxy materials online under the SEC’s “notice and access” rules. As a result, unless you previously requested electronic or paper delivery on an ongoing basis, we are mailing to our stockholders a Notice of Internet Availability of Proxy Materials (the “Notice”) instead of a paper copy of the proxy statement, our Annual Report on Form 10-K for the fiscal year ended March 31, 2026 (the “Annual Report”) and a form of proxy card or voting instruction card (together, the “proxy materials”). The Notice contains instructions on how to access the proxy materials online. The Notice also contains instructions on how stockholders can receive a paper copy of our proxy materials. If you elect to receive a paper copy, our proxy materials will be mailed to you. This distribution process is more resource- and cost-efficient. The Notice is first being mailed, and the proxy materials are first being made available, to our stockholders on or about July 21, 2026.

All stockholders are cordially invited to attend our Annual Meeting, conducted virtually via live audio webcast. To attend the Annual Meeting, vote, or submit questions during the Annual Meeting, you must first register for the Annual Meeting in advance by visitingwww.proxydocs.com/STEP. Upon completing your registration, you will receive a confirmation email, which will include additional information about virtually attending the Annual Meeting. For additional details, see “—How can I attend, participate in and vote at the Annual Meeting online?” in the “Questions & Answers About the Annual Meeting” section below. This proxy statement provides detailed information about the Annual Meeting. We encourage you to read this proxy statement carefully and in its entirety. When accessing our Annual Meeting, please allow ample time for online check-in, which will begin at 12:45 p.m. Eastern Time on Tuesday, September 8, 2026. If you experience technical difficulties during thecheck-in process or during the Annual Meeting, please call the phone number provided in your confirmation email for assistance. During the ten days prior to the Annual Meeting, a list of stockholders of record will be available at our principal executive offices located at 277 Park Avenue, 45th Floor, New York, New York 10172.

Your vote is important. Regardless of whether you participate in the Annual Meeting, we hope you vote as soon as possible. You may vote online or by phone, or, if you received paper copies of the proxy materials by mail, you may also vote by mail by following the instructions on the proxy card or voting instruction card. Voting online or by phone, written proxy or voting instruction card ensures your representation at the Annual Meeting regardless of whether you attend our virtual Annual Meeting online.

By Order of the Board of Directors,

Jennifer Y. Ishiguro

Chief Legal Officer & Secretary

New York, NY

July 21, 2026

IMPORTANT NOTICE REGARDING THE AVAILABILITY OF PROXY MATERIALS FOR THE ANNUAL MEETING OF STOCKHOLDERS TO BE HELD ON SEPTEMBER 8, 2026