Career
His position of preference was at prop. After attending Liston College, O'Neil started his career with the Marist Saints before making the Waitakere City Raiders side in the Lion Red Cup. He was an Auckland Warriors junior but did not break into first grade and instead played for the reserve grade team.
St Helens
In 1997 O'Neill moved to England and joined the St. Helens in the Super League competition. He played for St Helens RLFC at prop forward in their 1999 Super League Grand Final victory over Bradford Bulls. O'Neill played for St Helens RLFC at prop forward in their 2000 Super League Grand Final victory over Wigan Warriors.
Widnes
In 2001 O'Neill joined the Wakefield Trinity Wildcats but this move was not successful and O'Neill decided to move again at the end of the year, joining the Widnes Vikings. O'Neill spent four years at the Vikings, playing in 96 games for the club. In 2003 he played alongside namesake Julian O'Neill, who adopted the nickname Jules to avoid confusion.
Return to Auckland
In 2006 he returned to Auckland, playing for the Auckland Lions in the Bartercard Cup. He also made the New Zealand Residents side that competed in the 2006 Trans Tasman Quadrangular Series. In 2009 O'Neill played in the Fox Memorial competition for the Mt Albert Lions.
O'Neill also represented the United States national rugby league team.
