Sometimes considered conspecific with Brown Nunlet (Nonnula brunnea), on account of their plumages being very similar and their ranges being allopatric, the natural history of Fulvous-chinned Nunlet is very poorly known. This species is unobtrusive, and apparently is uncommon, or local in distribution. Nothing has been reported to date regarding its diet or reproductive biology. Its distribution extends from eastern Peru south to northern Bolivia, and east across southwestern Amazonian Brazil to the west bank of the Rio Madeira. Fulvous-chinned Nunlet is found in the open understory of primary lowland terra firme and seasonally flooded forests, often in or near bamboo thickets.