Marin, a Mexican American, was born in Los Angeles, California, the son of Elsa (née Meza), a secretary, and Oscar Marin, a policeman in the LAPD. He was raised Catholic. Marin is a graduate of California State University Northridge where he was a member of Phi Sigma Kappa. Fleeing from the U.S. draft during the height of the Vietnam War in 1968, Marin settled in Vancouver, British Columbia, where he met future comedic partner Tommy Chong.
As a part of the duo Cheech and Chong he participated in a number of comedy albums and feature film comedies. After he and Tommy went their separate ways, he starred in a number of films as a solo actor, most notably Born in East L.A., Tin Cup and Once Upon a Time in Mexico. His nickname "Cheech" is short for "Chicharron", a spicy fried pork skin which is a popular snack amongst Mexicans.
Marin made the transition to television when he co-starred with Don Johnson and Yasmine Bleeth in the police show Nash Bridges (1996-2001), in which they played San Francisco police-detective partners. In recent years he has been active in playing supporting roles in films and performing voice overs for animated features. His last television work included a supporting role in Judging Amy, where he played an independently wealthy landscape designer. He is a favorite of director Robert Rodriguez, who has worked with Marin seven times following the last two installments of his El Mariachi trilogy, the Spy Kids trilogy, From Dusk Till Dawn and the Machete trailer for Grindhouse. He provided his voice for several Disney animated films, most notably Tito in Oliver & Company (1988), Banzai in The Lion King (1994) and Ramone in Cars (2006). He also reprised the Banzai role in Kingdom Hearts II. He made a small appearance as a dockworker in the movie Ghostbusters 2. Marin has released a best-selling album in the children's music genre, My Name is Cheech, the School Bus Driver (1997). The album was released bilingually.
Marin is one of the foremost collectors of Chicano art in the United States, and his private collection is claimed to be the world's largest. Two national touring exhibitions have featured works from his collection. He is also an avid golfer, although Marin initially disliked the sport until he co-starred in Tin Cup. Marin was born with a cleft lip, which has long since been repaired. He speaks fluent Spanish[verification needed] and uses it in some of the movies he stars in. Marin's trademark is his character's Mexican-accented voice. The actor took a cue from his Nash Bridges counterpart as he resides in the San Francisco Bay Area year round, as a resident of the city's ritzy Sea Cliff neighborhood.
Marin was going to do the voice role of Cesar Vialpando from Grand Theft Auto: San Andreas but it went to Clifton Collins Jr.. In late 2006, Marin participated in Simon Cowell's Celebrity Duets, having sung with Peter Frampton, Randy Travis, Clint Black, Aaron Neville, and Al Jarreau. He was the fourth to be eliminated. In that same year, he voiced as Gaspar Gomez in Scarface: The World is Yours.
In the third season of the hit television series Lost, Marin plays Hurley's father.