From St. Louis, Missouri he was the eldest of seven children from a family that splintered when his mother died. At that time, he left home and rode the railroad at just twelve years old. He returned to St. Louis, and attended school while living at the home of Jewel Richie, his English and Diction teacher. In 1954, Gunn began a three-year service in the Army; he received his B. A. degree from Tennessee State University in 1959. After that he studied at the University of Kansas in their graduate program for speech and drama, they belatedly awarded him an M. A. degree in 1989. An authoritative Black character actor of film and TV, Gunn also enjoyed a successful career on stage, he made his NY stage debut in the original off-Broadway production of Jean Genet's The Blacks (1962).
A co-founder of the celebrated Negro Ensemble Company, he distinguished himself in many of their productions, notably The First Breeze of Summer (1975). Gunn was also known for his Shakespearean performances with the Yale Repertory Theatre and the New York Shakespeare Festival. Gunn rarely had comparable roles to showcase his talents in films, but his large, regal features and booming yet somewhat raspy voice stood out during his 25-year film career. Gunn may be best remembered as Bumpy Jonas, the powerful Harlem gangster whose daughter is kidnapped in Gordon Parks' Shaft (1971).
He reprised that role in Parks' Shafts Big Score (1972). Gunn was also memorable as Booker T. Washington in Ragtime (1981). His last major film was Clint Eastwood's Heartbreak Ridge (1986), in which he played aging vet Sergeant Webster. Gunn also worked extensively in TV. He was nominated for an Emmy for his portrayal of African chief Kintango in the first installment of "Roots" (ABC, 1977). Gunn joined the cast of the hit CBS sitcom "Good Times" in 1977 as Carl Dixon, the appliance store owner who marries the widowed Esther Rolle and whisks her away from the projects.
He was also a guest star on numerous series, including "The Cosby Show," "Equal Justice" and "Homicide". Moses Gunn costarred in South African playwright Athol Fugard’s Blood Knot and My Children, My Africa in 1993. He died on December 16 that same year in Guilford, Connecticut.