The name commemorates the last German Emperor and King of Prussia, Wilhelm II of Germany.

These two species, along with the red bird-of-paradise, are the only Paradisaea that perform inverted display.

The emperor bird-of-paradise is large, approximately 33 cm long, yellow and brown with a reddish-brown iris, bluish-grey bill and purplish-brown legs.

The male has an extensive dark emerald green face and throat, two very long tail wires and large white ornamental flank plumes.

The female is almost similar to the male, but has an all brown plumage, smaller in size and has no ornamental plumes.