O'Neill was one of the players from the Balmain club who was offered a contract to play for the newly formed Wests Tigers side.

O'Neill played in Wests Tigers inaugural match in round 1 of the 2000 NRL season against Brisbane at Campbelltown Stadium which finished in a 24–24 draw.

[4] Three weeks later, he was on the receiving end of a serious case of foul-play in 2004 when Danny Williams of the Melbourne Storm punched O'Neill in the face in an off the ball incident.

[5] In 2005 he was voted team captain, a title Scott Prince took over during O'Neill's twelve weeks absence with an elbow injury.

[7][8] O'Neill's contract at Leeds was not renewed and he spent 2007 at Hull Kingston Rovers where he played his final year in professional rugby league before retiring.