It is endemic to northern Peru where it is only known from near its type locality, Tarapoto in the San Martín Province, on the eastern slopes of the Cordillera Oriental.

The tympanum is distinct and only barely obscured by the diffuse supratympanic fold above.

[4][3] In most Allobates, the eggs are deposited in leaf litter; after hatching, the parents transport the tadpoles on their backs to small pools.

[5] The presence of very large eggs in a female Allobates ornatus suggests that this developmental strategy applies to this species too.

[1][4] Allobates ornatus is known from disturbed lowland rainforest and humid montane forest at elevations of 350–680 m (1,150–2,230 ft) above sea level.