Born in St. Paul, Minnesota, Boyle grew up in Cincinnati, Ohio. She studied architecture at Parson's School of Fine and Applied Arts in New York and elsewhere, took courses at Columbia, and studied violin briefly at the Cincinnati Conservatory of Music. She married French-born engineer Richard Brault in 1922 while helping to edit the experimental literary magazine Broom. She moved to France with her husband the following year, and she lived mostly in France from 1923 to 1941, where she was well known among the American expatriate community.
In 1926 she was erroneously diagnosed as suffering from tuberculosis. By that time the marriage to Brault had largely disintegrated, and she moved to Grasse, France, to live with Ernest Walsh, editor of This Ouarter. When Walsh died the following year, Boyle, who was then pregnant, moved to Paris. There she became active in the avant-garde artist and writers community and signed the famous "Revolution of the Word" manifesto in Eugene Jolas' magazine transition. Several of her books were published in the late 1920s and early 1930s, including Short Stories (1929), Wedding Day and Other Stories (1930), and the novel Plagued by the Nightingale (1931) . In the latter book a couple decides not to have children and are attacked as a result by their conservative family.
Boyle married Laurence Vail in 1932. During that decade they lived not only in France but also in Austria and England. Two lyrical novels, Year Before Last (1932) and My Next Bride (1934) draw on her own experience to assert a woman's right to sexual freedom and artistic independence. In 1936 she published Death of a Man, a novel that attacked Nazism before most Americans were aware it was a problem. The following year she wrote "A Communication to Nancy Cunard."
Boyle returned to the U.S. in 1941, divorced Vail in 1943, and married Baron Joseph von Franckenstein the same year. A series of novels about the German occupation of France and the French resistance to the Nazis followed: Primer for Combat (1942), Avalanche (1944), and A Frenchman Must Die (1946) . In 1947 the couple moved to Germany, Boyle to serve as a European correspondent for The New Yorker and von Franckenstein to work in the U.S. Foreign Service. After the onset of McCarthyism, von Franckenstein was fired. Back in the U.S. she was active in progressive movements for decades and was herself blacklisted. Meanwhile, The Smokinq Mountain: Stories of Germany During the Occupation (1951) is an unsually sensitive collection. A 1960 novel Generation Without Farewell takes the point of view of a German journalist who rejects his own country and admires Americans but finally realizes he belongs to neither county.
In 1963, after her husband's death, she moved to San Francisco and began teaching at San Francisco State University. Being Geniuses Together (1966) alternates her memoirs with those of Robert McAlmon. The Underground Woman (1975) is a novel about the student protest movement, a movement in which she participated. Altogether, she published ten novels, half a dozen short novels and numerous short story collections, three children's books, along with essays and several volumes of poetry.