The tree martin was formally described in 1817 by the French ornithologist Louis Vieillot under the binomial name Hirundo nigricans.

[4][5] The tree martin is now one of ten swallows placed in the genus Petrochelidon that was introduced in 1851 by the German ornithologist Jean Cabanis.

The adult has an iridescent blue back and crown, brown wings and tail, a rufous forehead and a whitish rump.

The sexes are similar, but young birds are duller and browner, with a paler forehead and pale fringes to the back and wing feathers.

Nests are constructed in natural holes in dead trees or rock crevices, but increasingly in artificial sites on bridges and buildings.