Macht was born in The Bronx, New York to Suzanna Victoria and actor Stephen Macht. He and his family moved to California when he was 5 years old. After graduating from high School he attended Carnegie Mellon College of Fine Arts.
Macht was nominated for the Best Young Motion Picture Actor award after playing his first role at age 8 in the film Why Would I Lie? under the stage name Gabriel Swann. He has appeared in many film and television roles including A Love Song for Bobby Long, Because I Said So, The Recruit and Archangel. Macht will play the title role in Frank Miller's adaptation of Will Eisner's The Spirit, scheduled for release in 2009.
Macht married actress Jacinda Barrett in 2004. The couple had their first child, a girl, Satine Anais Geraldine Macht, born August 20, 2007 in Los Angeles.