Bromfield's father was from New England and his mother's family were Ohio pioneers. Louis Bromfield grew up in Mansfield, Ohio. He studied agriculture at Cornell University, then journalism at Columbia University but left before completing a degree to served in the American Field Service in France during World War I. He received the Legion of Honor and the Croix de Guerre for his service. After the war, he worked as a reporter in New York.
He first novel, The Green Bay Tree (1924), drew immediate attention. It tells the story of a mysterious man who builds an estate outside a midwestern town, fueling speculation about his intentions and his endeavors. After the man's death, his widow and daughters continue to be the topic of fascination in the town. Eventually, steel mills surround the estate.
In 1925, Bromfield and his family visited France, a country Bromfield had become fascinated with during the war. They remained there until just before World War II. He became associated with the literary American ex-patriate community in Paris, making friends with Natalie Barney, Ernest Hemingway, Sinclair Lewis, Gertrude Stein, and Edith Wharton, among others.
Bromfield wrote 30 books, both fiction and non-fiction. Among them were A Good Woman (1927), about a woman who thinks of herself as righteous but ruins her son's life; The Rains Came (1937), a romance set in India; and Mrs. Parkington (1943), the story of a chambermaid who became a society matron; The Rains Came was adapted for a film in 1939, starring Tyrone Power, Myrna Loy, George Brent, and Brenda Joyce. Mrs. Parkington was produced as a film in 1944, starring Greer Garson and Walter Pidgeon.
Bromfield bought a 1,000-acre farm near his hometown in Ohio and pursued his studies in agriculture, becoming an early advocate of organic and self-sustaining gardening. He banned pesticide use on his farm.