Pristimantis fenestratus is a species of frog in the family Craugastoridae. It is found in the Amazon Basin of eastern Peru, northeastern Bolivia, southeastern Ecuador, southeastern Colombia, and Brazil. Its common name is Rio Mamore robber frog, after Mamoré River, its type locality. Its natural habitats are tropical humid montane and lowland forests; it can also occur in secondary forest and forest edges. It is very common in parts of its range.