Ron O'Neal grew up in a working-class neighborhood of Cleveland, Ohio, to the parents of Eunice and Ernest O'Neal a former jazz musician who earned his living as a factory worker; Ernest died when Ron was 16 years old. Only six months later his brother, who worked as a truck driver, was killed in an accident. Following these tragedies his mother found a job in a hospital to sustain the family. He graduated from Glenville High School, then attended Ohio State University, and there became interested in acting after seeing the play Finian's Rainbow. He joined the Karamu House company in Cleveland, Ohio, working with the oldest African-American theatre company in the United States from 1957 until 1964, during which period he appeared in plays such as Kiss Me, Kate, A Streetcar Named Desire and A Raisin in the Sun, while working as a housepainter to earn his living. In 1964, he went to New York, teaching acting classes at the Harlem Youth Arts Program and appearing in Off-Broadway plays.
In 1969, his theatrical breakthrough came in the Broadway play Ceremonies in Dark Old Men. In 1970, appearing in Charles Gordone's Pulitzer Prize-winning play No Place to Be Somebody, he garnered even more attention, winning an Obie Award and several other prizes. From there, he moved on to cinema with two minor roles in Move (1970) and The Organization (1971), after which he was contacted by a friend from Cleveland, Screenwriter Phillip Fenty, who suggested he star in an all-black film about a drug dealer. Although shot on a meager budget, the film, Super Fly (1972), went on to become a major hit at the box office.
O'Neal was first married to Actress Carol Tillery Banks, from November 1973 until 1980 (divorced), and then to Audrey Pool, from 1993 until his death in 2004.
During those years, film roles that went beyond stock characters were few and far between, notable exceptions being his roles in Brothers (1977), the television movie Brave New World (1980), and the miniseries The Sophisticated Gents (1981). He had a number of television guest appearances, frequently playing detective roles. In 1988, O'Neal had a recurring role as Mercer Gilbert on the popular NBC television sitcom A Different World, playing the wealthy father of the spoiled southern belle Whitley Gilbert (Jasmine Guy). His appearances lasted through 1992. In 1996, he appeared in the Blaxploitation reunion film Original Gangstas.
He died in Los Angeles on January 14, 2004, after a four-year battle with pancreatic cancer, on the same day Super Fly was released on DVD in the United States.
The Wu-Tang Clan's 2014 album A Better Tomorrow includes a song called "Ron O'Neal".
