Barbeau was born and raised in Sacramento, California, in 1945, the daughter of Armene (née Nalbandian) and Joseph Barbeau, who was a public relations executive for Mobil Oil. Her mother was of Armenian descent and her father's ancestry included French-Canadian, Irish, and German. She has a sister, Jocelyn, and a half brother on her father's side, Robert Barbeau, who still resides in the Sacramento area. She attended Del Mar High School in San Jose, California. In her autobiography, Barbeau says that she first caught the show Business bug while entertaining troops at army bases throughout Southeast Asia, touring with the San Jose Civic Light Opera.