GOLUB CAPITAL BDC, Inc.

We expect each of our officers and directors, as well as any person affiliated with our operations, to act in accordance with the highest standards of personal and professional integrity at all times and to comply with the Company’s policies and procedures and all laws, rules and regulations of any applicable international, federal, provincial, state or local government. To this effect, the Company has adopted a Code of Conduct, which is posted on the Company’s website atwww.golubcapitalbdc.com. The Code of Conduct applies to the Company’s directors, executive officers, officers and their respective staffs.

As required by the 1940 Act, we and GC Advisors have each adopted a Code of Ethics that establishes procedures that apply to our directors, executive officers, officers, their respective staffs and the employees of GC Advisors with respect to their personal investments and investment transactions. Our Code of Ethics generally does not permit investments by our directors, officers or any other covered person in securities that may be purchased or held by us. We filed our Code of Ethics as an exhibit to our Annual Report on Form 10-K, filed with the SEC on November 18, 2025, and you may access it via the Internet at the website of the SEC at www.sec.gov or our website atwww.golubcapitalbdc.com. We intend to disclose any material amendments to or waivers of required provisions of our Code of Conduct or the Code of Ethics on a Current Report on Form 8-K.

The Company has established a policy designed to prohibit officers, directors, and employees of the Company and GC Advisors from purchasing or selling securities of the Company while in possession of material nonpublic information, or otherwise using such information for their personal benefit or in any manner that would violate applicable laws and regulations. The policy also prohibits short-selling and margining of either the Company’s securities or the securities of existing or prospective portfolio companies. The policy does not expressly prohibit directors, executive officers or employees of the Company and its affiliates from purchasing financial instruments (including prepaid variable forward contracts, equity swaps, collars, and exchange funds), or otherwise engaging in transactions, that hedge or offset, or are designed to hedge or offset, any decrease in the market value of our common stock. However, the Company discourages trades by such persons that are of a short-term nature rather than for investment purposes, and all purchases and sales of the Company’s securities by directors, officers and employees of the Company and its affiliates must receive pre-clearance from the Company’s Chief Compliance Officer.