Three specimens of the scorpionfish Scorpaenopsis obtusa Randall & Eschmeyer, collected from Okinawa, Ryukyu Islands, Japan (URM-P 21256, 40.4 mm SL), Lizard Island, Queensland (AMS I. 19482-190, 37.8 mm SL) and Bedwell Island, Clerke Reef, Rowley Shoals, Western Australia (WAM-P 28037-001, 34.8 mm SL), represent the first reliable records from Japan and Australia (and the Indian Ocean) and northernmost and southernmost records of the species. The specimens are described herein and detailed comparisons made with a related species, S. gibbosa (Bloch & Schneider). The colour pattern of the inner surface of the pectoral fin of S. obtusa and a colour photograph of a fresh specimen are also figured for the first time. In addition, a nominal species, Scorpaena axillaris Bliss, 1883, is regarded as a junior synonym of Scorpaenopsis gibbosa. Validity of the previously recognized taxonomic characters of both species is assessed and new diagnostic characters are proposed.