Pete Duel was born in Rochester, New York, the eldest of three children born to Dr. Ellsworth and Lillian Deuel (née Ellstrom).

He had a younger brother, Geoffrey, who also became an actor, and a sister, Pamela. He attended Penfield High School, where he worked on the yearbook staff, campaigned for student government, and was a member of the National Thespians Society. Moving to New York, Deuel landed a role in a touring production of the comedy Take Her, She's Mine.