A detailed description and illustrations of a new terebellid species are provided, and molecular information based on partial sequences of the mitochondrial cytochrome c oxidase subunit I (COI) gene are included. The new species, Neoamphitrite undevigintipes sp. nov., is described from the deep sea off the eastern coast of South Korea. It is similar to Neoamphitrite groenlandica (Malmgren, 1866) in that the thorax has 19 notopodial chaetigers. However, Neoamphitrite undevigintipes sp. nov. is clearly distinguishable from N. groenlandica in having the uncini of the first abdominal chaetiger arranged in a single row and in having 12 ventral shields. A taxonomic key to all known Neoamphitrite species is also included.