Learned married Oscar winner Robert Donat's nephew Peter Donat, a Canadian citizen, when she was 17 years old, a marriage that lasted 17 years and produced three sons. She learned her craft while acting for the Shakespeare Festivals in both Canada and the U.S. while simultaneously raising a family. She and her husband Peter acted together with San Francisco's American Conservatory Theatre (ACT) in the early 1970s. Her breakthrough came when she was appearing in an ACT production of Noel Coward's "Private Lives", where she was spotted by producer Lee Rich, who cast her as Olivia Walton in his new television series about a Depression era family, "The Waltons" (1971).

Learned won three Emmy Awards playing the role, and another Emmy for her next foray into series TV, "Nurse" (1981). She escaped typecasting as Olivia Walton (although she re-prised the role that made her famous in a 1995 TV-movie reunion) while appearing on numerous shows and TV movies, including top-drawer, made-for-TV specials such as the 1986 adaptation of Arthur Miller's "American Playhouse: All My Sons (#6.1)" (1987) with co-star James Whitmore.