[1] After college, Williams moved to Philadelphia, where he collaborated with the New Freedom Theatre as an actor, worked as a salesman to pay his bills, and wrote in his free time.

[4] As Samm Williams, he wrote the play Welcome to Black River, produced by the Negro Ensemble Company (NEC) at St. Mark's Playhouse in 1975; and as Samm-Art Williams, The Coming and Do Unto Others, both at the Billie Holiday Theatre in Brooklyn in 1976; A Love Play produced by the NEC that same year; The Last Caravan (1977); and Brass Birds Don't Sing, at New York City's Stage 73 in 1978.

[citation needed] Williams participated in the NEC Playwrights Workshop under the guidance of playwright-in-residence Steve Carter, who strongly influenced his work.

"[5] Williams' comedy Home was mounted by the Negro Ensemble Company at St. Mark's Playhouse from 1979 to 1980,[citation needed] moving to Broadway's Cort Theatre from May 7, 1980, to January 4, 1981.

In the mid-1980s he appeared in television series including The New Mike Hammer, 227, and Frank's Place, a CBS dramedy for which he also served as a story editor.

Williams wrote the PBS productions Kneeslappers (1980) and Experiment in Freedom (American Playhouse, 1985); episodes for the series Cagney and Lacey, The New Mike Hammer, Miami Vice, and The Fresh Prince of Bel Air; the "John Henry" episode of the Showtime cable network series Shelley Duvall's Tall Tales & Legends; and the NBC special Motown Returns to the Apollo (1986), among other work.

[citation needed] Williams wrote and directed the comedy The Dance on Widows' Row, produced by the New Federal Theatre at Manhattan's Harry De Jur Playhouse at Henry Street Settlement from June 25 to July 30, 2000.

[9] In 2011, The Black Rep of St. Louis, Missouri, produced the world premiere of his play The Montford Point Marine, starring J. Samuel Davis.