Creamy-bellied Antwren is endemic to the east slope of the Andes in central and southern Peru, where it is found in the canopy and subcanopy of humid montane forest at 900–2100 m. Like other species of Herpsilochmus, pairs regularly join mixed species foraging flocks. Creamy-bellied Antwren was formerly treated as a subspecies of Bahia Antwren (Herpsilochmus pileatus), which at that time also incorporated those populations in central and eastern South America that now are known as Black-capped Antwren (Herpsilochmus atricapillus). The cream colored wash on the breast and belly of this antwren is pale, and often is not readily apparent in the field. Otherwise the plumage pattern of this species is similar to that of many other species in the genus. The upperparts are primarily gray, but it has a black crown, tail, and wings, the latter with white wingbars' There is a conspicuous whitish supercilium, and the underparts are pale off-white, with a creamy wash on the throat and breast. The sexes are similar, but the female has a buffy forecrown, and the crown is streaked with white. Otherwise very little is known about the natural history of Creamy-bellied Antwren.