Some of Williams roles included Pretty Tony in The Mack (1973), the limo driver in Dog Day Afternoon (1975), Denzel Washington's father in Mo' Better Blues (1990) and Officer Allen in Edward Scissorhands (1990), and his other film credits include Uptight (1968), The Anderson Tapes (1971), Who Killed Mary What's 'Er Name?
(1971), Five on the Black Hand Side (1973), Deadly Hero (1975), The Deep (1977), An Almost Perfect Affair (1979), The Jerk (1979), The Night the City Screamed (1980), The Star Chamber (1983), Gardens of Stone (1987), The Players Club (1998), and Blood and Bone (2009).
Williams was a regular cast member on the post World War II–era ABC primetime soap opera Homefront (1991-1993), appearing in all 42 episodes as chauffeur Abe Davis.
Williams also starred in the documentary film The Meeting, about Malcolm X and Martin Luther King Jr. discussing the fate of black people in America.
In 1971–1972, Williams appeared in Melvin Van Peebles' acclaimed off-Broadway musical Ain't Supposed to Die a Natural Death.