Cobb left in 1950 to join Earl Bostic, and cut his first recordings with him. He played with Dinah Washington over three years, then worked with Cannonball Adderley, Stan Getz, and Dizzy Gillespie. He took over for Philly Joe Jones in the Davis band in 1958, and was on hand for several seminal dates. He finally left, along with Paul Chambers, to team with Wynton Kelly. The trio played and recorded with Wes Montgomery, Kenny Burrell, and J.J. Johnson before it disbanded. Cobb played on the soundtrack for the film Seven Days in May, and later worked with David Amram. He worked with Sarah Vaughan through the '70s, and was featured on a public television film of a Vaughan concert at the Wolf Trap Jazz Festival. Cobb also worked with Richie Cole, Sonny Stitt, Nat Adderley, and Ricky Ford. During the '80s he worked with the Joe Albany trio.

For all his session work from the '50s onward, Cobb was not particularly known as a leader on his own dates, and rather extraordinarily began developing his own discography in earnest beginning during the late '90s and extending across the first decade of the 2000s, starting (after 1994's Encounter, a duo release with singer Ada Montillanico) with Only for the Pure of Heart by Jimmy Cobb's Mob in 1998. A second Cobb's Mob album, Cobb's Groove, was released by Milestone in 2003. Tribute to Wynton Kelly & Paul Chambers by the Jimmy Cobb Trio was issued by the Japanese Sound Hills label in 2004, followed by two Chesky releases by the Jimmy Cobb Quartet, Cobb’s Corner in 2007 and Jazz in the Key of Blue in 2009. In addition, the Marsalis Music Honors series released a Jimmy Cobb volume in 2006, featuring Cobb on drums along with Ellis Marsalis on piano, Andrew Speight on saxophone, and Orlando Le Fleming on bass. Cobb received a National Endowment for the Arts Jazz Masters award in October 2008.