The fourhorn sculpin was first formally described as Cottus quadricornus in the 10th edition of Linnaeus's Systema Naturae with its type locality given as the Baltic Sea.

[4] The deepwater sculpin Myoxocephalus thompsonii of continental North American freshwater lakes (e.g., the Great Lakes) is closely related to the fourhorn sculpin and alternatively considered as a subspecies of the latter, Myoxocephalus quadricornis thompsonii.

The fourhorn sculpin has a large knobbly head with protruding lips and four bony protuberances, though the latter are not present in freshwater, lake forms of this fish.

[5] The fourhorn sculpin is a demersal fish distributed mainly in brackish arctic coastal waters in Canada, Greenland, Russia, and Alaska, and also as a relict in the boreal Baltic Sea.

There are also freshwater populations in the lakes of Norway, Sweden, Finland and Karelia and in Arctic Canada (Nunavut and Northwest Territories).