Was briefly engaged to novelist, essayist and screenwriter Gore Vidal before breaking the engagement to pledge herself to eventual husband Paul Newman. The new couple, who remained friends with Vidal, briefly lived with him in a house in Los Angeles.
When she was 9 years old, Joanne traveled with her mother to Atlanta for the premiere of Gone with the Wind (1939). During the parade, she leapt into a limousine carrying Laurence Olivier and sat in his lap as she had a crush on him after seeing Wuthering Heights (1939). Years later when the two were working on Come Back, Little Sheba (1977) (TV), Olivier claimed to remember the incident vividly.
Wore a handmade dress that cost about $100 to the 1957 Oscar ceremony (the year she won Best Actress for Three Faces of Eve).