Shawn Lalonde was born on March 10, 1990, in Orleans, Ontario. An offensive defenceman from the Belleville Bulls of the Ontario Hockey League, Lalonde was selected by the Chicago Blackhawks in the third round of the 2008 NHL Entry Draft.
When his Bulls missed out on the OHL playoffs, Lalonde was assigned to play for the Blackhawks American Hockey League affiliate, the Rockford Icehogs, for the remainder of the 2009-10 season. He would appear in eight regular season games and three playoff games for the club, scoring a goal and adding an assist.
Lalonde made his NHL debut for the Blackhawks on April 27, 2013 against the St. Louis Blues. Playing both the wing and defence, he finished with a +1 rating, having been on the ice for the only goal of the hockey game.
On July 24, 2013, Lalonde left the Blackhawks organization and signed a one-year contract with German club, Eisbären Berlin.