He also owned the publication La Voix du Nord and served as president of the companies Mont-Laurier Aviation and Lievre Lumber.
Lalonde practised law in Mont-Laurier.He was first elected to Parliament at the Labelle riding in the 1935 general election and re-elected in 1940 and 1945.
Lalonde did not seek another term in the 1949 election.His son Fernand served in the Quebec assembly.