27-year-old O'Neill made his last appearance for his club in a reserve game, but a troublesome back injury made it impossible for him to play to his potential.
O’Neill confirmed what many had suspected in the game, for a while, today when announcing his retirement from football through a club statement.
It reads, 'As you can imagine, I feel robbed of my best footballing years, but I have been lucky enough to live out a dream for the last ten.'
'I have also been fortunate enough to work alongside the world’s best players and managers. That has been a great honour.'
'I wish Coventry City every success for the future and am sorry that I have not been able to contribute greatly over the last couple of years. For that, I can only apologise.'
'I would like to thank my family, girlfriend and all my friends who have been so supportive, sharing my highs and enduring my lows.'
'And finally, I retire content that I have had the opportunity to play football for the greatest nation in the world.'
O'Neill's playing career saw him begin with Norwich City and enjoy spells with Middlesboro and Coventry City.
He played 13 times for the Republic between 1996 and 1999, and was one of the brightest prospects to emerge from the early managerial days of Mick McCarthy. He made his debut under the Barnsley man as a substitute against Portugal in the summer of 1996. He also managed to score his first goal on his first start for Ireland, in a 2-2 draw at Lansdowne Road against Croatia.
Eerily enough Millwall's Richard Sadlier, also a striker, was forced to call it quits in September, as a hip injury ravaged the last years of his career.
O'Neill last played for the Republic as a substitute in a Euro 2000 qualifier 1-1 draw with Macedonia in Skopje in 1999. Sadlier unfortunately made just one appearance for his country.