According to an interview at the Tulane Jazz Archive with Oliver's widow Stella Oliver, in 1919 a fight broke out at a dance where Oliver was playing, and the police arrested Oliver and the band along with the fighters. This made Oliver decide to leave the Jim Crow South.
After travels in California, by 1922 Oliver was the jazz "King" in Chicago, with King Oliver and his Creole Jazz Band performing at the Royal Gardens (later renamed the Lincoln Gardens). Virtually all the members of this band had notable solo careers. Personnel was Oliver on cornet, his protegé Louis Armstrong, second cornet, Baby Dodds, drums, Johnny Dodds, clarinet, Lil Hardin, (later Armstrong's wife) on piano, Honore Dutray on trombone, and Bill Johnson, bass and banjo. Recordings made by this group in 1923 demonstrated the serious artistry of the New Orleans style of collective improvisation or Dixieland music to a wider audience.
In the mid and late 1920s Oliver's band transformed into a hybrid of the old New Orleans style jazz band and the nationally popular larger dance band, and was christened "King Oliver & His Dixie Syncopators". Oliver started to suffer from gum disease which started to diminish his playing abilities, but remained a popular band leader through the decade.
The Great Depression was harsh to Oliver; he lost his life savings when a Chicago bank collapsed, as he struggled to keep his band together on a series of hand-to-mouth gigs until the band broke up and Oliver was stranded in Savanah, Georgia, where he worked as a janitor and died in poverty.
As a player, Oliver was strongly interested in altering his horn's sound. He pioneered in the use of mutes, including the plumber's plunger, derby hat, and bottles and cups in the bell of his horn. His recording "WaWaWa" with the Dixie Syncopators can be credited with giving the name wah-wah to such techniques.
Although Oliver performed mostly on cornet, the instrument is virtually identical to the trumpet. Oliver is second on the historical list of the greatest jazz trumpet innovators: Buddy Bolden, Oliver, Armstrong, Roy Eldridge, Dizzy Gillespie, and Miles Davis.
Oliver was also noted as a composer, having written Armstrong's early hit, "Dippermouth Blues", as well as "Sweet Like This", "Canal Street Blues", and "Doctor Jazz", the latter virtually the theme song of Jelly Roll Morton, a frequent collaborator.
Louis Armstrong called Oliver his idol and inspiration all his life.