As a youth, Lalonde played in the 2003 Quebec International Pee-Wee Hockey Tournament with a minor ice hockey team from Cumberland, Ontario. Lalonde was drafted 68th overall by the Chicago Blackhawks in the 2008 NHL Entry Draft. Lalonde signed a three-year entry-level contract with the Blackhawks on December 31, 2009. At the time, Lalonde played for the Belleville Bulls, a junior team in the Ontario Hockey League. In the 2009–10 season, Lalonde led the Bulls' defense and finished first on his team by scoring with 56 points in 58 games, earning selection to the OHL Third All-Star Team. After finishing out of the OHL playoffs, Lalonde was assigned to play for the Blackhawks American Hockey League affiliate, the Rockford Icehogs, on March 16, 2010. Lalonde scored his first professional goal with the Icehogs in a 4–3 victory over the Peoria Rivermen on March 26, before appearing in three playoff games with the IceHogs. On April 14, 2011, the Chicago Blackhawks called Lalonde up to the NHL. Lalonde made his NHL debut for the Blackhawks on April 27, 2013, against the St. Louis Blues. He had 14:47 of ice time, playing both the wing and defence and finishing the game as a +1, being on ice for Chicago's only goal of the contest. Lalonde remained with the Blackhawks during their playoff run. On July 24, 2013, Lalonde left the Blackhawks organization and signed a one-year contract with German club Eisbären Berlin of the DEL. In the 2013–14 season, Lalonde quickly established himself amongst the Berlin blueline, finishing the season as the top scoring defenceman with 12 goals and 30 points. Unable to agree on an extension with Berlin on April 28, 2014, Lalonde signed a contract with Swedish club Färjestad BK. In his only season in Sweden, Lalonde failed to adapt his offensive presence and numbers from the DEL in producing 13 points from 50 regular season games. For the 2015–16 season he returned to Germany, signing a two-year contract with the Kölner Haie of the DEL. Lalonde regained his scoring touch for his previous stint in Germany and led all defenseman in the DEL in goals over the following two seasons. During the 2017–18 season, Lalonde posted 6 goals and 18 points in 44 games before his contract was terminated by Kölner Haie on February 27, 2018. He remained in Germany for the 2018-19 season, recording 8 goals and 31 points in 49 games with the Thomas Sabo Ice Tigers. As a free agent, Lalonde agreed to move to the KHL, signing a one-year contract with Russian club, Admiral Vladivostok, on May 10, 2019. In his debut season in the KHL in 2019–20, Lalonde co-led the team in scoring from the blueline registering 7 goals and 26 points in 54 games. On May 1, 2020, Lalonde left Admiral at the conclusion of his contract and moved to Severstal Cherepovets by agreeing to a one-year contract as a free agent.
