Gwen Welles was born in Chattanooga, Tennessee, as Gwen Goldberg. She was the daughter of Actress Rebecca Weis Welles (born 1928) and Barton Goldberg; her sisters were Elizabeth (Betsy) Goldberg Welles and Lori Yarom. Gwen graduated from University High School in Los Angeles, California and attended Vassar College in Poughkeepsie, New York. Welles was married to actor Harris Yulin in 1975.
Gwen Welles may be best remembered for her portrayal of talentless singer "Sueleen Gay", in Robert Altman's 1975 film Nashville, for which she was nominated for a BAFTA Award, for Best Supporting Actress. Welles also appeared in several films directed by Henry Jaglom, including New Year's Day (1989) and Eating (1990).
She died in 1993 from anal cancer, aged 42. Her younger sister, Elizabeth (Betsy Goldberg Welles), died from colon cancer 10 years later. Donna Deitch directed a documentary about Welles' illness in 1992, which appeared at the 1998 Berlin Film Festival.
