We describe Atrimitra isolata sp. n. (Gastropoda: Mitridae), collected on the summit of seamounts (similar to 200 m water depth) in the vicinity of Desventuradas Islands, Chile insular territory. Additionally, we provide some insight into the habitat of this new species based on underwater imagery taken with a remotely operated vehicle. A. isolata sp. n. is characterized by its small size (up to 26 mm), elongate-ovate shape, solid shell and smooth appearance. It has a base brown color, with some specimens being tan or yellow. It is morphologically related to counterparts from shallow depths on the west coast of North, Central and South America (i.e., Atrimitra idae, Atrimitra orientalis and Atrimitra semigranosa), but has no affinities with species of the family reported from around Easter Island, on the far western side of the Salas y Gomez ridge (e.g., Strigatella flavocingulata, Imbricariopsis punctata and Neocancilla takiisaoi), or with other Indo-Pacific species. The present contribution adds to the knowledge of the poorly studied fauna of the seamounts in the southern portion of the Nazca ridge and easternmost section of the Sala y Gomez ridge, an area characterized by the high degree of endemism of its benthic fauna, and now protected within the large and newly created Nazca-Desventuradas Marine Park.