UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 14A

(RULE 14a-101)

Proxy Statement Pursuant to Section 14(a) of the

Securities Exchange Act of 1934

Filed by the Registrant  ☒    Filed by a Party other than the Registrant  ☐

Check the appropriate box:

☐	Preliminary Proxy Statement
☐	Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)(2))
☐	Definitive Proxy Statement
☒	Definitive Additional Materials
☐	Soliciting Material Pursuant to §240.14a-12

Sixth Street Specialty Lending, 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):

☒	No fee required.
☐	Fee paid previously with preliminary materials.
☐	Fee computed on table in exhibit required by Item 25(b) per Exchange Act Rules 14a-6(i)(1) and 0-11

6 SIXTH STREET SPECIALTY LENDING SIXTH STREET SPECIALTY LENDING, INC. 2100 MCKINNEY AVENUE, SUITE 1500 DALLAS, TX 75201 Your Vote Counts! SIXTH STREET SPECIALTY LENDING, INC. 2024 Annual Meeting Vote by May 22, 2024 11:59 PM ET You invested in SIXTH STREET SPECIALTY LENDING, INC. and it’s time to vote! You have the right to vote on proposals being presented at the Annual Meeting. This is an important notice regarding the availability of proxy material for the stockholder meeting to be held on May 23, 2024. Get informed before you vote View the Notice & Proxy Statement, Annual Report on Form 10-K online OR you can receive a free paper or email copy of the material(s) by requesting prior to May 09, 2024. If you would like to request a copy of the material(s) for this and/or future stockholder meetings, you may (1) visit www.ProxyVote.com, (2) call 1-800-579-1639 or (3) send an email to sendmaterial@proxyvote.com. If sending an email, please include your control number (indicated below) in the subject line. Unless requested, you will not otherwise receive a paper or email copy. For complete information and to vote, visit www.ProxyVote.com Control # Smartphone users Point your camera here and vote without entering a control number Vote in Person at the Meeting* May 23, 2024 9:30 AM EDT Simpson Thacher & Bartlett LLP 425 Lexington Avenue, 30th Floor New York, NY 10017 *Please check the meeting materials for any special requirements for meeting attendance. At the meeting, you will need to request a ballot to vote these shares.

Vote at www.ProxyVote.com THIS IS NOT A VOTABLE BALLOT This is an overview of the proposals being presented at the upcoming stockholder meeting. Please follow the instructions on the reverse side to vote these important matters. Voting Items Board Recommends 1. Election of Directors Nominees: 01) David Stiepleman 02) Richard Higginbotham 03) Ronald Tanemura For 2. To ratify the selection of KPMG LLP as the Company’s independent registered public accounting firm for the fiscal year ending December 31, 2024. For NOTE: The named proxies are also authorized to transact such other business as may properly come before the 2024 Annual Meeting of Stockholders or any postponement or adjournment thereof. Prefer to receive an email instead? While voting on www.ProxyVote.com, be sure to click “Sign up for E-delivery”.