He came to prominence as sideman with the likes of Lester Young, Gerry Mulligan, Count Basie and Lena Horne. Hamilton then struck out as a bandleader, first with a quintet featuring the cello as a lead instrument, an unusual choice for a jazz band in the 1950s, and subsequently leading a number of groups over the years that performed cool jazz, post bop and jazz fusion.
Hamilton started his career in a band with Charles Mingus, Illinois Jacquet, Ernie Royal, Dexter Gordon, Buddy Collette and Jack Kelso before he had finished high school. Engagements with Lionel Hampton, Slim & Slam, T-Bone Walker, Lester Young, Count Basie, Duke Ellington, Charlie Barnet, Billy Eckstine, Nat King Cole, Sammy Davis Jr., Billie Holiday, Gerry Mulligan and Lena Horne established his career.
Hamilton appeared in You’ll Never Get Rich (1941) as part of the backing group supporting Fred Astaire. Hamilton also performed on the soundtrack of the Bing Crosby and Bob Hope film Road to Bali (1952).