Frank O'Hara, the son of Russell Joseph O'Hara and Katherine (née Broderick) was born on March 27, 1926, at Maryland General Hospital, Baltimore, and grew up in Grafton, Massachusetts. He attended St. John's High School. He grew up believing he had been born in June, but in fact had been born in March, his parents having disguised his true date of birth because he was conceived out of wedlock. He studied piano at the New England Conservatory in Boston from 1941 to 1944 and served in the South Pacific and Japan as a sonarman on the destroyer USS Nicholas during World War II.
With the funding made available to veterans he attended Harvard University, where artist and writer Edward Gorey was his roommate. O'Hara was heavily influenced by visual art and by contemporary music, which was his first love (he remained a fine piano player all his life and would often shock new partners by suddenly playing swathes of Rachmaninoff when visiting them). His favorite poets were Arthur Rimbaud, Stéphane Mallarmé, Boris Pasternak, and Vladimir Mayakovsky. While at Harvard, O'Hara met John Ashbery and began publishing poems in the Harvard Advocate. Despite his love of music, O'Hara changed his major and graduated from Harvard in 1950 with a degree in English.
He then attended graduate school at the University of Michigan in Ann Arbor. While at Michigan, he won a Hopwood Award and received his M.A. in English literature in 1951. That autumn O'Hara moved into an apartment in New York City with Joe LeSueur, who would be his roommate and sometime lover for the next 11 years. It was during this time that he began teaching at The New School.
Known throughout his life for his extreme sociability, passion, and warmth, O'Hara had hundreds of friends and lovers throughout his life, many from the New York art and poetry worlds. Soon after arriving in New York, he was employed at the Museum of Modern Art, selling postcards at the admissions desk, and began to write seriously.
O'Hara was active in the art world, working as a reviewer for Artnews, and in 1960 was Assistant Curator of Painting and Sculpture Exhibitions for the Museum of Modern Art. He was also a friend of the artists Willem de Kooning, Norman Bluhm, Larry Rivers and Joan Mitchell.
In the early morning hours of July 24, 1966, O'Hara was struck by a jeep on the Fire Island beach, after the beach taxi in which he had been riding with a group of friends broke down in the dark. He died the next day of a ruptured liver. Attempts to bring negligent homicide charges against 23 year-old driver Kenneth L. Ruzicka were unsuccessful; many of O'Hara's friends felt the local police had conducted a lax investigation to protect one of their own locals. O'Hara was buried in Green River Cemetery on Long Island. The painter Larry Rivers, a longtime friend and lover of O'Hara's, delivered one of the eulogies, along with Bill Berkson, Edwin Denby and René d'Harnoncourt.