The Shaft-tailed Whydah is a small bird, around 13 cm in length. The male Shaft-tailed Whydah in breeding plumage has a long tail, up to 16 cm in length, made up of 4 feathers, ending with a flag feather.
The breeding male has a black back and crown. The rest of his plumage is golden in colour.
The bill is red and the legs are a pink to red colour. The female and non-breeding male Shaft-tailed Whydah have a dark brown crown with rusty coloured streaks. The bill and feet are pink in colour.
The Shaft-tailed Whydah is polygynous, with the male having several females in his group. This whydah is a brood parasite and the female lays her eggs in the nest of a waxbill.
The violet-eared waxbill (Granatina granatina) being the primary host and the black-faced waxbill (Estrilda erythronotos) being the secondary host.