After his Major junior career was over, he signed as an undrafted free agent with the Vancouver Canucks. He played seven games with the Canucks, but played most of his first professional season with the Dallas Black Hawks of the Central Hockey League. McDonnell bounced around in the AHL until the 1984–85 NHL season where he played 40 games with the Pittsburgh Penguins, scoring 2 goals and 11 points for the Penguins in 40 games that season. After playing only three games in the NHL next season; all with the Penguins, he retired from professional hockey.
After being fired by the Rangers, McDonnell found work with the Detroit Red Wings as an amateur scout. After eight seasons as a scout, McDonnell was promoted to Director of Amateur Scouting for the Red Wings. He won the Stanley Cup four times with Detroit, in 1997, 1998, 2002 and 2008.[4] McDonnell, along with Red Wings General managerKen Holland, former Red Wings executive Jim Nill, and current Red Wings scout Håkan Andersson have been partially credited with the success of the Detroit Red Wings.[5][6]
On July 6, 2013, McDonnell as well as Red Wings scout Mark Leach followed former colleague Jim Nill to the Dallas Stars, where McDonnell was hired as Director of Amateur Scouting for the Dallas Stars, the same position he held in Detroit.[7]