[2][3] After attending DePaul University for a period of time, he took courses from the Association for the Advancement of Creative Musicians, where he studied under founders Anthony Braxton and Roscoe Mitchell.

According to longtime Grateful Dead manager Rock Scully, Williams occasionally performed in ad-hoc ensembles at the Blues Bar (a private TriBeCa afterhours club operated by Saturday Night Live cast members Dan Aykroyd and John Belushi, throughout their tenure on the show in the late 1970s) with such 1960s rock luminaries as Rick Danko and Bill Kreutzmann.

[5][6] Williams toured and recorded with the Peter Brötzmann Tentet, the Vandermark 5, Cinghiale, Our Daughter's Wedding, and Mark Freeland's Electroman, and was the bandleader of several spin-off jazz groups: Grammy Award nominated, acid jazz pioneer Liquid Soul, Hal Russell's NRG Ensemble, Witches & Devils, Slam, and XmarsX.

He was active in the Chicago improvisational jazz underground scene both individually and as a member of the quartet Extraordinary Popular Delusions.

[9] With Boneshaker (Mars Williams, Paal Nilssen-Love, Kent Kessler) With the NRG Ensemble With Liquid Soul With Switchback (Mars Williams / Wacław Zimpel / Hilliard Greene / Klaus Kugel) With Harrison Bankhead With Peter Brötzmann With Hal Russell / NRG Ensemble With Ken Vandermark With The Swollen Monkeys With The Luck of Eden Hall (Alligators Eat Gumdrops, ltd edition 200, 2012) With Custard Flux