Marjorie Muir Worthington was born in 1900 in New York City. She initially aspired to be an artist and attended various art schools during her early years. While still in high school she began selling poems to magazines. Thus encouraged, she turned to journalism, which she studied at New York University School of Journalism. Her novel Spider Web, the fifth she had written, was published by Cape & Smith in 1930.

In 1926, Worthington traveled to Paris where she joined ranks with other expatriate American artists and writers to whom Gertrude Stein referred as the "lost generation." There she met William Seabrook, well-known author in his own right, with whom she spent most of her time. She divorced her second husband, Lyman Worthington, in 1932; she had first been married to Carlton Beecher Stetson. While in France, Worthington and Seabrook socialized with notable figures of the age - Ford Maddox Ford, Sinclair Lewis, Gertrude Stein and Alice B. Toklas, Aldous Huxley, Thomas Mann, and Walter Duranty.

In 1932, Seabrook and Worthington journeyed to Africa to gather material for one of his books. While there, Worthington fell in love with Raymond Bauret, a Frenchman. She returned to France with Seabrook however, and they married in 1935. His experiments in witchcraft and voodooism, compounded by his bouts of sadism and alcoholism, led to their divorce in 1941. Seabrook committed suicide in 1945.

Meanwhile, Worthington continued to write novels and short stories. Eleven of her novels were published and many of her short stories appeared in magazines such as Vogue, McCall's, Vanity Fair, Harper's, and Cosmopolitan. Some of these short stories were adapted for radio and television. In the 1950's and 1960's, Worthington began writing biographies and three were published: Miss Alcott of Concord (Louisa May Alcott), The Immortal Lovers (Heloise and Abelard), and The Strange World of Willie Seabrook (William Seabrook). Her last major published work was the book about Seabrook, brought out in 1966.

After her divorce from Seabrook, Worthington spent the rest of her life in New York and Florida. During this time she continued to write despite publishers' rejections. In addition to writing, Worthington lectured and led writers' workshops. She died February 17, 1976 of cancer.