She was born in Philadelphia, Pennsylvania, and died after an automobile accident in Monaco. Her Irish Catholic family were new but prominent figures in Philadelphia society. Her father John B. Kelly, Sr., was a self-made millionaire and a gold-medal-winning Olympic sculler, and her brother "Jack" followed in that tradition, and Kelly Drive in Philadelphia is named for John, Jr., who was a city councilman there.
Though her family had opposed her becoming an actress, Kelly became a fashion model and appeared in her first film, Fourteen Hours (1951), when she was 22. The following year she starred in High Noon (1952), a generally praised but somewhat controversial western starring Gary Cooper.
The film Mogambo, a drama set in the Kenyan jungle (1953), centers on the love triangle portrayed by Kelly, Clark Gable, and Ava Gardner and earned Kelly an Oscar nomination for Best Actress in a Supporting Role. (Donna Reed won for her role in From Here to Eternity.) Kelly made three films with Alfred Hitchcock: Dial M for Murder, Rear Window, and To Catch a Thief.
In 1955 she was awarded the Academy Award for Best Actress in a Leading Role for The Country Girl (1954). While it was being filmed she had engaged in a brief affair with its star Bing Crosby that was kept quiet to protect both their reputations.
The musical comedy High Society (1956) was her last film, as her marriage to Prince Rainier III of Monaco marked her retirement from acting. Before her marriage, she was previously involved with Clark Gable, Bing Crosby, Ray Milland, William Holden, Oleg Cassini, and Jean-Pierre Aumont. She reportedly was surprised to learn from Rainier that she was to give up her film career entirely but followed his wishes.
Her being Catholic and able to bear children were key factors in her being chosen to marry Prince Rainier, as dynasties always make great import of their survival. Tales were circulated that because Monaco would revert to France because there was no heir, and though there is no requirement for a Catholic marriage, it was thought unlikely that a Catholic prince would divorce and remarry if his chosen wife was barren. In fact, there was really little actual danger that Monaco would revert to France as, since 1882, a childless prince of Monaco has been able to adopt an unrelated heir, thereby ensuring Monaco's survival as a principality. Prince Rainier's paternal grandfather, Prince Louis II of Monaco had done just that in 1919, when he adopted his illegitimate daughter, Charlotte Louvet, who would become Rainier's mother, and made her his heir, Princess Charlotte of Monaco. Nonetheless, survival of the nation was a different matter than the survival of the dynasty, and here there was a history of concern about fertility. Before Grace Kelly came on the scene, French film star Gisèle Pascal was Rainier's love interest for six years (she was born Gisèle Tallone in Cannes, France). Gisele and Rainier supposedly parted when a physical examination reportedly found her to be infertile (she later married and had children).
Prince Rainier and Princess Grace had three children:
At the age of 52, Princess Grace suffered a stroke while driving on the same stretch of highway in Monaco that had figured in To Catch a Thief. It resulted in an accident, and she died the next day without regaining consciousness. Princess Stephanie, who was alleged in some sources to have been the actual driver of the car, suffered only minor injuries.