Beltran honed his acting skills as a member of the California Shakespeare Festival appearing in "A Midsummer Night's Dream", "Hamlet", and "Henry IV". He met celebrated playwright, screenwriter and director Luis Valdez and played a small role in his film adaptation of his play "Zoot Suit" (1981). Beltran went on to work with Valdez's "workers'" theater company "El Teatro Campesino" and had his first starring stage role in Valdez's "Corridos". He also collaborated with the playwright on "Rose of the Rancho", "La Pastorela" and "I Don't Have to Show You No Stinkin' Badges". Beltran remains active on the LA stage where he co-founded and serves as co-artistic director of the East Los Angeles Classic Theater Group.
Beltran tends to be cast as Chicanos and American Indians. He made his TV acting debut playing a Sioux brave in "The Mystic Warrior" (ABC, 1984), a historical miniseries. He went on to numerous guest shots and TV-movies as well as starring in several busted pilots. Beltran also had a recurring role on the primetime soap "Models Inc." (Fox, 1994) as the intrepid Lieutenant Soto. He hitched his fortunes to the stars as a regular on "Star Trek: Voyager" (UPN, 1995- ) playing the spiritual Native American First Officer Chakotay.