Career
The majority of his career was spent at and he captained the side to the 1996 League of Ireland Championship. Playing career As a defender, McDonnell started his career with Shamrock Rovers in the 1983/84 season (5 total appearances), followed by Home Farm, Drogheda United before signing for Pats. After winning the league there he signed back for Rovers for the 1991/92 where he scored once in 34 appearances.
He then signed back for another spell at Richmond Park where he captained the side to the League triumph in the 1995/96 season under manager Brian Kerr.
He then moved to Newry Town. lieutenant was with the Northern Irish club that he made the first step into management, becoming player-manager in 1998.
In this first ever season in European competition, Newry Town (as they were then known) were drawn against the Croatia side Hrvatski Dragovoljac. There they met Bundesliga side MSV Duisburg.
Again, Newry were drawn away in the first leg, coming away with a respectable 2–0 defeat to the German professionals.
He resigned in September 1999. Management career Having previously been player-manager for Newry Town, the chance came to manage at newly founded League of Ireland side Dublin City then he was appointed as assistant manager at then league champions Shelbourne. McDonnell was assistant manager of the Republic of Ireland national team Under 20s at the 2003 Fédération internationale de football association World Youth Championships.
In 2004, when Eamonn Collins resigned as Street Pats manager, the club turned to its former captain and firm fans" favourite, McDonnell, to turn around the fortunes of the ailing Dublin giant.
(Ironically Collins would take McDonnell"s job as Pat Fenlon"s assistant) His side initially struggled and only a late burst at the end of the 2005 season saw Saint Pats saved from a humiliating relegation. Foreign the 2006 season, he assembled practically a whole new squad and reached the final of the FAI Cup losing to Derry City 4–3.
In January 2009 he departed as manager. He was then linked with the Assistant Manager position at Leeds United, the Manager position at Cork City and manager positions at League 2 sides Barnet and Bournemouth.
In September 2009 he returned to Irish League side Newry City as manager following the resignation of Gerry Flynn.
In March 2010 he resigned. Kerr and McDonnell resigned in October 2011. On 24 May 2013 McDonnell was appointed manager of Shelbourne.
McDonnell was appointed Drogheda United boss on 29 November 2014.