Jean-Marc Lalonde (born 1935) is a politician in Ontario, Canada. He is currently a member of the Legislative Assembly of Ontario, representing the riding of Glengarry—Prescott—Russell for the Ontario Liberal Party.

Lalonde was employed in the Public Service of Canada from 1956 to 1990. He served for a time as the manager of the Canadian Government Printing Bureau, and was responsible for the establishment and operation of technical training and development for the Canada Communications Group. Outside of public service, Lalonde was a co-owner of the Hull Olympiques ice hockey team in the Quebec Junior Hockey League for the time, and was a director of the Canadian Amateur Hockey Association from 1972 to 1976.

He was also mayor of Rockland, Ontario from 1976 to 1991. For eleven years, Lalonde was a director of the Association of Municipalities of Ontario, and was also the vice-president of the Association for Francophone Municipalities of Ontario for a time.

Lalonde was first elected to the Ontario legislature in the 1995 provincial election, in the safe Liberal (and predominantly francophone) seat of Prescott and Russell in the easternmost section of the province. The Progressive Conservatives won the election, and Lalonde joined 29 other Liberals in the official opposition. He was re-elected without difficulty in the new riding of Glengarry-Prescott-Russell in the general election of 1999.

The Liberals won the 2003 election, in which Lalonde defeated his closest opponent by almost 20,000 votes. On September 27, 2004, he was named parliamentary assistant to Harinder Takhar, the Ontario Minister of Transportation.

Jean-Marc Lalonde now serves as the Parliamentary Assistant to the Minister of Economic Development and Trade.

In the 2007 election, Jean-Marc Lalonde was re-elected in his riding by a commanding margin over PC candidate Dennis Pommainville.