Spillmann's tapaculo is 12 cm (4.7 in) long. Males weigh 21 to 30 g (0.74 to 1.06 oz) and females 20 to 29.5 g (0.71 to 1.04 oz). The male is blackish gray above with a dark brown rump. It is lighter gray below with tawny to cinnamon flanks and vent area. Some females are like the male, but most have the upperparts heavily washed with brown and an orange lower belly. The juvenile is brown above and dusky below, with barring above and below.
Spillmann's tapaculo is found in all three Andean ranges of Colombia and south into Ecuador. In the west it extends to Cotopaxi Province and in the east into Morona-Santiago Province. It inhabits the undergrowth of humid montane forest and is especially partial to Chusquea bamboo. It ranges generally from 1,900 to 3,200 m (6,200 to 10,500 ft) but is found locally up to 3,500 m (11,500 ft) and as high as 3,700 m (12,100 ft) in western Napo Province, Ecuador.
Spillmann's tapaculo forages on the ground or near it, mostly for small insects.
Little is known about the breeding phenology of Spillmann's tapaculo, but it probably breeds throughout the year.