Recruited from Melbourne High School Old Boys Association, Ahern made his VFL debut in round 1 in 1989 against Fitzroy, having eight disposals.
Ahern did not player senior football for North Melbourne and was delisted at the end of the 1991 season.
Following his retirement, Ahern began a career in hospitality by obtaining the lease of the Mortlake Pub TAB.
The successful creation of the Hamilton Sporting Club was his first major project from conception to completion from 1994 to 1997.
In 2002 with a strong management background he moved into ownership, commencing with successful nightclub Aqua.