The band-bellied owl is fairly large, ranging from 44 to 48 cm (17 to 19 in) long. An analysis of the weight of 13 birds of both sexes showed a range of 590 to 1,250 g (1.30 to 2.76 lb) and an average of 873 g (1.925 lb). The adult has a dark brown facial disk and white "brows" over dark reddish brown eyes. Its upperparts are dark chocolate brown with scattered buffy-white spots. The tail is also dark brown, with thin white bars. The upper breast is reddish brown with buff barring. The rest of the underparts are white to creamy with reddish brown barring. The juvenile's plumage has not been described.
The nominate subspecies of band-bellied owl is found on the eastern slope of the Andes from central Colombia south through Ecuador and Peru. P. m. philoscia is found from there to west-central Bolivia. In elevation it ranges from about 650 to 2,200 m (2,130 to 7,220 ft). It primarily inhabits the interior of humid montane forest and foothills rainforest but is also found on forest edges and in clearings with scattered trees.
The band-bellied owl is nocturnal. Its diet is poorly studied but is known to include large insects.
Though there is no published information on the band-bellied owl's breeding phenology, it is presumed to nest in natural tree cavities.