After working small clubs in Milwaukee while awaiting the transfer of his Musicians Union card to the Chicago local, Aton responded to an advertisement in the Variety trade journal to audition with the Chicago-based Herbie Fields Band.

While not a commercial success, the Fields band of 1950, consisting of a 12-man unit and a six-man combo, nurtured several talented future jazz stars, including pianist Bill Evans, trumpeter Jimmy Nottingham and trombonist Frank Rosolino.

There followed a steady stream of work in Hollywood clubs with a variety of Jazz stars including Conley Graves, The Page Cavanaugh Trio, Calvin Jackson and Harold Land.

Aton departed the quintet (replaced by Carson Smith) to become a staff bassist at Gold Star Records, where he joined some of the most talented session players in the business.

In 1959, Aton joined pianist-singer Nancy Malcom, guitarist Al Viola and drummer Mel Lewis on the critically acclaimed RCA-Camden LP, The West Coast of Broadway (later reissued on CD).

In 1972, Aton settled in Lake Tahoe, where he worked a multi-year casino engagement playing organ in the Earl Hines Quartet, and as a first-call bassist for numerous shows in the Reno-Tahoe area.

In later years Aton frequently led small combos—often including trumpeter Fred Padden, bassist Chuck DiLaura and drummer Pete Spomer backing various vocalists.

Jim was the older brother of Richard "Dick" Aton (1927-2003), also an accomplished jazz pianist who performed over a long career with such West Coast recording artists as saxophonists Harold Land and Zoot Sims and trumpeter Jack Sheldon.