[1] O'Neill played four years at Yale University before spending the 1989–90 season with Tappara Tampere of the SM-liiga.
O'Neill returned to the minors and, in 1995–96, made 74 appearances with the Baltimore Bandits, an AHL record.
[citation needed] O'Neill was signed as a free agent by Anaheim and made his debut on December 11, 1997 against Pittsburgh relieving Mikhail Shtalenkov halfway through the second period, allowing 3 goals on 10 shots.
He then signed with the Washington Capitals as a free agent in August 1997 and played 47 games for the Portland Pirates of the AHL in 1997–98.
[citation needed] O'Neill played for EC VSV in Austria in the 1998–99 season before returning to North America to play for the Long Beach Ice Dogs and the Michigan K-Wings during 1999–00 season.