The Miocene deposits of the Agnevo Formation cropping out along the western coast of Sakhalin Island, Russia, are widely known for the well-preserved fossil remains of marine organisms, including a diverse assemblage of primarily benthic and demersal teleost fishes. †Sakhalinia multispinata, gen et sp. nov., a new cottoid fish from the Miocene (Serravallian-Tortonian) finely laminated sandstone of the Agnevo Formation, is described herein based on a single, nearly complete specimen in part and counterpart. Several morphological features indicate that †Sakhalinia multispinata is a basal member of the cottoid family Hexagrammidae. Within hexagrammids, †Sakhalinia multispinata exhibits a unique combination of features and is primarily typified by slender and recurved jaw teeth, 44 (22 22) vertebrae, 14 (6 8) principal caudal fin rays, a moderate consolidation of the caudal skeleton, an entire dorsal fin with 25 thick spines and 13 soft rays, anal fin with four strong spines and 12 soft rays, and ctenoid scales. The elongated, slender, and recurved jaw teeth displayed by †Sakhalinia multispinata suggest that this hexagrammid fish was specialized to feed mainly on small crustaceans.