Exhibit 31.3

CERTIFICATIONS

I, Marvin L. White, certify that:

1.I have reviewed this Amendment No. 1 to Form 10-K amending the Annual Report on Form 10‑K for the fiscal year ended December 31, 2020 of Aptevo Therapeutics Inc.;

2.Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report.