Milan B. Williams came from Mississippi and began playing the piano after watching his older brother Earl, who was a multi-instrumentalist. Prior to joining The Commodores, Milan did his keyboard-wizardry in a rivaling band called The Jays. When The Jays disbanded, Milan was recruited. He was in the very first edition of The Commodores and in 1969 traveled with the group to New York, where they recorded a single called "Keep On Dancing" on Atlantic Records.

Among the tracks Milan wrote are The Commodores' first hit record "Machine Gun", "The Bump", "Rapid Fire", "I'm Ready", "Better Never Than Forever", "Mary Mary", "Quick Draw", "Patch It Up", "X-Rated Movie", "Wonderland", "Old-Fashion Love" and "Only You" (a track Milan also produced, taken from The Commodores first Richie-less LP "13" in 1983).

In addition, Milan penned "You Don't Know That I Know", "Let's Get Started", "Brick House", "Too Hot Ta Trot" (with the group), "I Feel Sanctified" (with the group and Jeffrey Bowen), "Gonna Blow Your Mind" (with Walter Orange) and "Lay Back" (with Dennis Lambert, Franne Gold and Martin Page). Milan, together with James Anthony Carmichael, produced "I Wanna Rock You" (co-written by Milan with K. Cover) and "Ain't Givin' Up" with Hawk Wolinski, a track written by Milan, Tyron Stanton and Paula E. Smith.

Milan left the Commodores in 1989, allegedly after refusing to perform with them in South Africa.