UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d)

of the Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): January 27, 2021

Sixth Street Specialty Lending, Inc.

(Exact name of registrant as specified in charter)

Registrant’s telephone number, including area code: (469) 621-3001

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

Securities registered pursuant to Section 12(b) of the Act:

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter).

Emerging growth company  ☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act.  ☐

Item 8.01 – Other Events

On January 27, 2021, Sixth Street Specialty Lending, Inc. (the “Company”) entered into an underwriting agreement (the “Underwriting Agreement”) by and among the Company, Sixth Street Specialty Lending Advisers, LLC (the “Adviser”) and BofA Securities, Inc., as representative of the several underwriters named in Schedule 1 thereto (the “Underwriters”), in connection with the issuance and sale of $300,000,000 aggregate principal amount of the Company’s 2.500% Notes due 2026 (the “Offering”).

The Offering was made pursuant to the Company’s effective shelf registration statement on Form N-2 (Registration No. 333-231271) previously filed with the Securities and Exchange Commission, as supplemented by a preliminary prospectus supplement dated January 27, 2021 and a final prospectus supplement dated January 27, 2021.

The foregoing description of the Underwriting Agreement does not purport to be complete and is qualified in its entirety by reference to the full text of the Underwriting Agreement filed with this report as Exhibit 1.1 and which is incorporated herein by reference.

Item 9.01 – Financial Statements and Exhibits

(d) Exhibits:

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, as amended, the Registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.