Ron graduated from Glenville High School and attended Ohio State University, where he 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.

That same year, he acted in Charles Gordone's Pulitzer Prize-winning play No Place to Be Somebody,[1] he garnered even more attention, winning an Obie Award and several other prizes.

He played a recurring role as police detective, Isadore Smalls, in the TV series The Equalizer, which ran for three seasons in the mid-1980s and starred British actor, Edward Woodward.

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.

O'Neal 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.