Sonic the Hedgehog 3, often abbreviated and literally known in Europe as Sonic 3, is a platform game in the Sonic the Hedgehog series for the Sega Mega Drive/Genesis. It was developed by Sonic Team in collaboration with Sega Technical Institute, and was published by Sega. The game debuted worldwide in the first half of 1994.

The game is closely tied to its direct sequel Sonic & Knuckles, as the two games were originally one until time constraints and cartridge costs forced the game to be split into two interlocking parts. Combined, both games have sold over 4 million copies.