Trejo spent many years of his early life in prisons on drug and robbery convictions. Trejo was a changed man after completing a life-changing 12-step rehabilitation program. Upon his release, Trejo got involved with several rehabilitation and counseling programs to help people struggling with problems he struggled once with.
In 1985, he met a young man at a Cocaine Anonymous meeting. He incidentally met the same struggling addict on the set of ‘Runaway Train,’ and Trejo was offered a role as a convict. Trejo was offered a chance to train Eric Roberts for a film, and interestingly he was eventually offered the role as his opponent in the ring.
After portraying several characters in films like ‘The Hidden (1987),’ ‘Lock-Up (1989),’ ‘Marked for Death (1990),’ ‘Mi Vida Loca (1993),’ and ‘Heat (1995),’ Trejo formed an alliance with Robert Rodriguez with the 1995 film ‘Desperado.’ The duo then moved to big-budget films like ‘Con Air (1997)’ and ‘The Replacement Killers (1998).’
Trejo portrayed the role of Uncle Isadore "Machete" Cortez in Robert Rodriguez’s 2001 super hit, ‘Spy Kids.’ He later appeared in sequels of both the films, and also starred in Rodriguez's ‘Once Upon a Time in Mexico (2002).’
He continued working on big as well as small screens in a variety of projects, such as Alias, The Devil's Rejects, Monk, SherryBaby, Snoop Dogg's Hood of Horror, and Smiley Face. Thereafter, he appeared in Valley of Angels, A Very Harold & Kumar Christmas, Saint John of Las Vegas, and Bad Ass.