He was born to actor Stephen Macht and his mother Suzanne Victoria Pulier is a museum curator. He was raised in a Jewish family with three siblings, Ari, Jesse and Julie. He completed his schooling from the Beverly Hills High School and enrolled at the Carnegie Mellon College of Fine Arts for graduation and graduated in 1994.
Gabriel’s began his acting career when he was just eight with the film Why Would I Lie. He then went on to appear in several film and television roles for Archangel, Because I Said So, The Recruit and A Love Song for Bobby Long etc. He also starred in the 2001 film titled Behind Enemy Lines. For this film, the hangar bay #3 of the USS Carl Vinson was chosen, and he was asked to spend a week at sea. The film was filmed on corridors, flight deck and hangar.
Macht was signed to work in drama Suits by the USA Network in 2010. Through this drama Gabriel became a well-known celeb.
He married Australian actress Jacinda Barrett in 2004. The couple is blessed with a daughter Satine Anais Geraldine Macht and a son Luca.
He is a vegetarian and is an ardent supporter of green living.