EXHIBIT 32.1

CERTIFICATION PURSUANT TO

18 U.S.C. SECTION 1350,

AS ADOPTED PURSUANT TO

SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

In connection with the quarterly report of Apollo Investment Corporation (the “Company”) on Form 10-Q for the period ended December 31, 2021 (the “Report”), I, Howard Widra, Chief Executive Officer of the Company, and I, Gregory W. Hunt, Chief Financial Officer of the Company, each certify, pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, that:

1.To my knowledge, the Report fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934; and

2.The information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of the Company.

/s/ HOWARD WIDRA

Howard Widra

Chief Executive Officer

February 3, 2022

/s/ GREGORY W. HUNT

Gregory W. Hunt

Chief Financial Officer and Treasurer

February 3, 2022