Hamilton was born in New York City. In 1941, he received a BA from Harvard University. He was later a conscientious objector during World War II. He wrote 14 plays, which were produced in New York, Los Angeles and other cities as well as several novels, the most important of which is Kevin (St. Martin's Press, 1980).
Kevin tells the story of the teenager of the same name, a boy from a broken home who meets Bruce, a 35-year-old man, while hustling at the waterfront. In 1992, Kevin was adapted as Gossenkind, a German movie by Peter Kern. Hamilton also reviewed books for The Village Voice and other publications.
Hamilton died on September 5, 1983 in Beth Israel Medical Center, one week after injuring himself in a fall at his home in Greenwich Village.