Adults are 13 cm (5.1 in) long and weigh 18 g (0.63 oz) on average, and are mostly blue with black masks, wings, and tails.

The blue-and-black tanager is listed as being of least concern by the International Union for Conservation of Nature (IUCN) on the IUCN Red List due to its large range, relative commonness, and lack of significant population declines, but is threatened by habitat destruction.

[2] Blue-and-black tanager is the official common name designated by the International Ornithologists' Union.

[5] The blue-and-black tanager is an average-sized species for its genus, with a mean length of 13 cm (5.1 in) and mass of 18 g (0.63 oz).

Populations of the subspecies atrocoerulea may also be confused with the golden-naped tanager, but can be distinguished by their blacker back and lack of cinnamon underparts.

[5] The blue-and-black tanager's calls include a thin, high-pitched tsit, a slightly lower swit, a repeated swit-swit-swit, and a hard SWIT-it.

[5] The blue-and-black tanager is found in Bolivia, Colombia, Ecuador, Peru and Venezuela in the northern and central Andes, at elevations of 1,500–3,500 m (4,900–11,500 ft).

It also inhabits forest edges, vegetation in clearings, and patches of growth near the tree line.

[5] The blue-and-black tanager joins large mixed-species flocks while foraging, most often in pairs or groups of 3–6 individuals.

It makes cup nests out of moss and rootlets, lined on the outside with Chusquea bamboo leaves and on the inside with fibers and animal hair.

[7] The subspecies atrocoerulea, which is considered a distinct species by the IUCN, is also listed as least concern for the above reasons.