Plain-breasted piculet endemic to South America on the eastern side of the Andes where it lives in the western part of the Amazon basin. The species is present in southern Colombia, eastern Ecuador, Peru and western Brazil at altitudes of up to . It is found in open parts of humid lowland forests, flooded forests, riverside corridors, swamps, thickets and groves, and logged areas with secondary growth and wooded pastures. It often occurs in areas of young "Cecropia" and "Mimosa" trees. The plain-breasted piculet is usually seen by itself or in pairs, but it will occasionally joins small flocks of birds of
White-barred piculet with several other species of piculet where their ranges overlap; these include the varzea ("P. varzeae") along the Amazon River, the ochre-collared ("P. temminckii") in southeastern Brazil, the ocellated ("P. dorbignyanus") in Bolivia, and the white-wedged piculet ("P. albosquamatus"), also in Bolivia. The white-barred piculet is between long. The sexes differ in that the male has red streaks or a solid red patch on the fore-crown, while the female lacks this. The rest of the crown is black, speckled with white. The upper parts of the body are tan or olive-brown, faintly barred with white, and the main flight feathers