He has been working steadily since 1979 in both theater and in films. He has won The Nosostros Golden Eagle Award for Outstanding Actor in a Television Series (1997) and been nominated for the NCLR Bravo Award for Outstanding Television Series Actor in a Crossover Role (1996), the Alma Award for Outstanding Individual Performance in a Television Series in a Crossover Role (1998, 1999).

Beltran is the seventh son of first generation Mexican-American parents, and refers to himself as being "Latindio". He has seven brothers and two sisters. He was born in Bakersfield, California where he attended East Bakersfield High School and Bakersfield College. He graduated from California State University, Fresno with a degree in Theater Arts and moved on to Los Angeles to begin his acting career. He had his first film role in Zoot Suit, in 1981.

Beltran founded and co-directed the East LA Classic Theater Group. He is also a member of the Classical Theater Lab, an ensemble of professional actors who co-produced his production of Hamlet in 1997, which he directed as well as starred in.

One of Beltran's siblings was born with Down Syndrome and for four years (1998 - 2001), he hosted the Galaxy Ball, a fund raising event for the Down Syndrome Association of Los Angeles (DSALA), which brought together actors from other Star Trek series for a small convention. During the evening, there was a cabaret and a dinner dance. In 2001, it was reported in USA Today that the Galaxy Ball raised more than US$50,000 for the DSALA, as well as other charities.

One of Robert's brothers is the well-known Latin Jazz musician Louie Cruz Beltran.