Born in Bellshill, O'Donnell began his career with Dundee United, making his first-team début in March 2002 and featuring six times in the final months of 2001–02, signing an extended contract in the process. The following season, O'Donnell featured in fourteen matches, scoring a hat-trick in the League Cup and netting in the Scottish Cup defeat to Hibernian.
Born in Bellshill, O'Donnell started his career with Dundee United, making his first-team debut in March 2002 and appearing six times towards the end of the 2001–02 season, securing an extended contract during that time. The following year, O'Donnell played in fourteen matches, scoring a hat-trick in the League Cup and netting in the Scottish Cup loss to Hibernian.