Born Tobias Vincent Maguire, Tobey's parents were 18 and 20 and unwed when he was born. His father, Vincent, was a cook. His mother, Wendy, was a secretary. They split two years after his birth, leaving Maguire to ricochet between them, moving constantly around California, Washington, and Oregon.

Tobey started out in the business working the usual commercial and TV-bit circuit taking on small parts untill eventually landing a starring role in a short-lived Fox sitcom, Great Scott!