He then returned to Bohemians where he played for just one season (1999–20), gaining an FAI Cup Runners up medal before being snapped up on a free transfer by English Football League One club AFC Bournemouth, where he played 168 league games and scored 24 goals.
He made just one appearance in his final season for Burnley as a late substitute against Scunthorpe United in January 2008.
Rather unfortunately, Garreth never made the impact at Kenilworth Road that had been hoped for, and after just 7 appearances for Luton Town (3 coming in the League), he was released by manager Mick Harford as the January 2008 transfer window opened.
On the eve of the 2009 season, O'Connor returned to Dublin and signed for St. Patrick's Athletic after non fruitful trials with Bohemians and Dundalk.
Garreth scored a memorable goal in the 2–1 defeat to Steaua București in the Europa League play-off during St Pats 2009 European campaign.