The rare jawfish Opistognathus trimaculatus Hiramatsu and Endo 2013 is newly recorded from the East China Sea, based on a single specimen collected from the west of Yaku-shima Island, Kagoshima, Japan. It was previously known only from Tosa Bay (type locality) and the Kii Channel, both located off the Pacific coasts of southern Japan. The new specimen, therefore, represents the first record of O. trimaculatus from the East China Sea, extending its known range approximately 640 km southwest from Tosa Bay. The species’ diagnosis is amended, with comments on interspecific variation.