Harris was born on June 4, 1931, in Oklahoma City, Oklahoma, the daughter of John P., an oil executive, and Dora (Veal) Harris. Harris was educated in her home state, attending Cottey College from 1945 to 1951, then transferring to the University of Oklahoma, where she received a bachelor of arts degree in 1953 and a master of arts degree in 1955.

Harris's first collection of short stories, King's Ex, was published by Doubleday in 1967. After that Harris proved a prolific author, publishing seventeen books, including novels, short stories, romance/ historical fiction and children's fiction in a twenty-year period from 1970 to 1989. These works, in addition to those listed above, include In the Midst of Earth (1969), The Peppersalt Land (1970), The Runaway's Diary (1971), The Conjurers (1974), Bledding Sorrow (1976), The Portent (1980), The Last Great Love (1981), Warrick (1985), Night Games (1987), and Lost and Found (1991). Harris's work has received a wide readership; in 1983, nine million of her books were in print, and her work has been translated into many languages, including French, German, Spanish, Portuguese, Polish, and Japanese. She has also been an author in residence at Oklahoma's Central State University.