O'Donnell had started his professional career with Motherwell in 1990 and claimed a Scottish Cup winner's medal in his first season. He continued to impress, winning the Scottish PFA Young Player of the Year Award in 1992 and 1994. In 1994, he transferred to Celtic for a fee of £1.75 million, which remains the highest fee ever earned by a Motherwell player.
He earned another Scottish Cup medal and won a league title with Celtic, but his time in Glasgow was plagued by injuries and he left the club in 1999. After an uneventful time at Sheffield Wednesday, where he made only 20 appearances in four seasons, he returned to Motherwell in 2004.
Motherwell were enjoying a successful season in 2007-08. Going into the match on 29 December, they were sitting third in the table, which is where they would finish the season.
O'Donnell was just about to be substituted before he collapsed. His nephew, David Clarkson, was also playing for Motherwell that day and had to be substituted himself after seeing his uncle taken away in an ambulance.
After O'Donnell's death, supporters around the world paid tribute, some by leaving mementos, including scarves and shirts, at Motherwell's Fir Park ground.