Janice Rule was born in Norwood, Ohio, to parents of Irish origin. Her father was a dealer in industrial diamonds.
She began dancing at the Chez Paree nightclub at fifteen, which paid for ballet lessons, and was a dancer in the 1949 Broadway production of Miss Liberty. Rule also studied acting at the Chicago Professional School.
She was pictured on the cover of Life magazine of 8 January 1951, as being someone to watch in the entertainment industry. Given a contract by Warner Bros., her first credited screen role was as Virginia in Goodbye My Fancy (1951), which featured Joan Crawford in the lead. The established star though, belittled the younger woman, making her work on the film difficult, although it should be noted that Joan Crawford years later wrote a letter of apology to Ms. Rule for treating her badly on this film. and Rule's Warner contract was allowed to lapse after only two films. She was troubled by the attitude toward women's beauty at the studios in the early 1950s: "Because I was afraid of being robbed of my individuality, I fought with the makeup people, the hairdressers, and I didn't understand problems of the publicity department," she was reported as saying in 1957.
During the 1960s she became interested in psychoanalysis. She began her formal studies in 1973, specializing in treating her fellow actors, and received her Ph.D ten years later from the Southern California Psychoanalytic Institute in Los Angeles. She practiced in New York and Los Angeles and continued to act occasionally until her death from a cerebral hemorrhage in 2003.