Cozzens grew up on Staten Island, N.Y., graduated from the Kent (Conn.) School (1922), and attended Harvard University for two years. In a year of teaching in Cuba he accumulated background material for the short novels Cockpit (1928) and The Son of Perdition (1929). He gained critical attention in 1931, when his novella S.S. San Pedro won the Scribner's prize. Thereafter he published increasingly complex novels, most of which focus on professional people. In The Last Adam (1933) the protagonist is a doctor; Men and Brethren (1936) depicts the life of an Episcopalian minister; The Just and the Unjust (1942) and By Love Possessed (1957) are about lawyers; and Guard of Honor (1948) concerns air force officers and men. Ask Me Tomorrow (1940) is an autobiographical novel, and Children and Others (1964) is a short-story collection.

Cozzens' works reflect a philosophy of political and social conservatism, and some have maintained that he was slow to receive widespread critical acclaim because of his conservative views. Acclaim did come, however; he received the Pulitzer Prize for fiction in 1949 for Guard of Honor and the Howells Medal of the American Academy of Arts and Letters in 1960 for By Love Possessed. The latter was also Cozzens' greatest popular success. His later works became increasingly convoluted in plot and style, especially his last novel, Morning Noon and Night (1968). A collection of his works, with critical appraisals, can be found in Just Representations (1978).