The white-throated swallow is 14–17 cm long. It has glossy dark blue upperparts and a bright chestnut crown. A dark blue-black breast band separates the white throat from the greyish white underparts and underwing coverts. The upper wings, underwing flight feathers and forked tail are blackish-blue, but the undertail has white patches near the feather tips. The white throat and blackish breast band are distinctions from similar Hirundo species. The outer feathers are slightly longer in the male than the female. Juveniles are duller than the adult, with shorter outer tail feathers and a browner crown. The call is a mix of warbles and twitters.