On June 29, 1956, Monroe married playwright Arthur Miller, whom she first met in 1950, in a civil ceremony in White Plains, New York. City Court Judge Seymour D. Robinowitz presided over the hushed ceremony in the law office of Sam Slavitt (the wedding had been kept secret from both the press and the public). Monroe and Miller wed again two days later in a Jewish ceremony before a small group of guests. Rabbi Robert E. Goldburg, a Reform rabbi at Congregation Mishkan Israel, presided over the ceremony. Their nuptials were celebrated at the home of Miller's literary agent, Kay Brown, in Westchester County, NY. Some 30 friends and relatives attended the hastily arranged party. Less than two weeks after the wedding, the Millers flew to London, where they were greeted at Parkside House by Laurence Olivier and wife Vivien Leigh. Monroe created chaos among the normally staid British press. In reflecting on his courtship of Monroe, Miller wrote, "She was a whirling light to me then, all paradox and enticing mystery, street-tough one moment, then lifted by a lyrical and poetic sensitivity that few retain past early adolescence." Nominally raised as a Christian, she converted to Judaism before marrying Miller. After she finished shooting The Prince and the Showgirl with Laurence Olivier, the couple returned to the United States from England and discovered she was pregnant. Tony Curtis, her co-star from Some Like It Hot, claims he got Monroe pregnant during their on-off affair that was rekindled during the filming of Some Like It Hot in 1959, while she was still married to Arthur Miller.
Miller's screenplay for The Misfits, a story about a despairing divorcée, was meant to be a Valentine gift for his wife, but by the time filming started in 1960 their marriage was beyond repair. A Mexican divorce was granted on January 24, 1961 in Ciudad Juarez by Francisco José Gómez Fraire. On February 17, 1962, Miller married Inge Morath, one of the Magnum photographers recording the making of The Misfits.
In January 1964, Miller's play After The Fall opened, featuring a beautiful and devouring shrew named Maggie. Simone Signoret noted in her autobiography the morbidity of Miller and Elia Kazan resuming their professional association "over a casket". In interviews and in his autobiography, Miller insisted that Maggie was not based on Monroe. However, he never pretended that his last Broadway-bound work, Finishing the Picture, was not based on the making of The Misfits. He appeared in the documentary The Century of the Self, lamenting the psychological work being done on her before her death.