Sonic is a mobian hedgehog with blue fur that covers most of his body, peach skin that covers his arms, muzzle and torso. He had jet black eyes in his younger years but developed emerald green eyes as he became older (although this trait has been portrayed inconsistently). He was also shorter and stubbier as a child, but has grown significantly taller and thinner since then.

Sonic has six head quills dropping back from the back of his head, two quills protruding from his back drooping downward.