The first formal description of the black redstart was by the German naturalist Samuel Gottlieb Gmelin in 1774 under the binomial name Mottacilla ochruros.

The genus name Phoenicurus is from phoinix, "red", and -ouros -"tailed", and the specific ochruros is from okhros, "pale yellow" and -ouros.

As these are separated by different behaviour and ecological requirements and have not evolved fertilisation barriers, the two European species can produce apparently fertile and viable hybrids.

Basal central and eastern Asian forms which diverged from the ancestral stock as the species slowly spread west (c. 3–1.5 mya).

The female is grey (western subspecies) to grey-brown (eastern subspecies) overall except for the orange-red lower rump and tail, greyer than the common redstart; at any age the grey axillaries and underwing coverts are also distinctive (in the Common Redstart these are buff to orange-red).

It is resident in the milder parts of its range, but north-eastern birds migrate to winter in southern and western Europe and Asia, and north Africa.

Migrant black redstarts arrive in Britain in October or November and either move on or remain to winter, returning eastward in March or April.

It will catch passing insects in flight, and migrants often hunt in coastal tide-wrack for flies or tiny crustaceans.

The nest is built by the female and is typically placed in a crevice or hole in rock or a wall or on a ledge of a building.

The nest consists of a loose cup of grass and stems and is lined with hair, wool and feathers.