The two London clubs were the subject of separate FA investigations - West Ham in relation to their game at Tottenham on November 25, and Millwall over abuse caught on camera by Sky Sports News' Special Report team.
Police arrested several West Ham fans following allegations of anti-semitic abuse at White Hart Lane, while two Millwall supporters featured in February's Special Report were subsequently issued with club banning orders.
And FA investigators are satisfied with both clubs' continuing efforts to deal with abusive behaviour.
Among the conclusions drawn in a statement on its website, the FA noted West Ham's work ahead of a return fixture with Tottenham which passed off without incident.
And, with reference to Millwall, the statement highlighted "the work the club continues to do in partnership with its local community to educate supporters and help tackle discriminatory language/behaviour".