Watson was born in Oakland, California and grew up on a ranch near Stockton. His father was a sheep rancher and his mother a school Teacher. His grandparents were from Texas. He attended Franklin Elementary School and graduated from Elk Grove High School in 1958. His family didn't have a television during his childhood and like most families of that era listened to the radio for news and entertainment. After high school he went to San Francisco State University for two semesters where he studied acting for a short time under Victor French.

Watson has appeared in guest roles in numerous TV series such as Hawaii Five-O, Emergency!, McCloud, M*A*S*H, The Rockford Files, The A-Team, CHiPs, and Murder She Wrote, as well as movies including ...tick...tick...tick... (1970), The Wild Country (1970), Dirty Little Billy (1972), Charley and the Angel (1973), Papillon (1973), The Midnight Man (1974), Treasure of Matecumbe (1976), Up In Smoke (1978), Cujo (1983) and Bulletproof (1988). He also had a part in the TV miniseries War and Remembrance (1988), which he filmed in Hawaii.

The acting role he considers his personal favorite and most fun was as Deputy Perkins on The Misadventures of Sheriff Lobo. He appeared on the March 22-28, 1980 cover of TV Guide as the character along with co-stars Claude Akins and Brian Kerwin.

After appearing in a small independent film, he wanted to pursue more formal acting training and he applied to and was accepted as a student at the Royal Academy of Dramatic Art in London, where he acquired a lot of stage experience. Says Watson, "I figured if I got in, I wouldn't have any excuse to fail on a training level. I could never say I didn't get the right kind of training, because this was the best in the world." Returning from England, he moved to Lost Angeles and began appearing in television shows and movies, eventually retiring from acting in the early 1990s.

His last role was in the 1992 television film Gunsmoke: To the Last Man.