Wallace's hawk-eagle is a small, boldly-patterned bird of prey. The head is orangey-brown, with blackish streaks, and a dark crest with white tips sticks up from the back of the head. The upperparts are very dark brown, and the underparts are buffish-white with narrow, dark barring. There are two subspecies; unlike Nisaetus nanus nanus, Nisaetus nanus stresemanni juveniles have white heads and underparts. It is frequently confused with Blyth's hawk-eagle (Spizaetus alboniger), making this species’ status hard to determine.