Lawrence John Cannon (November 18, 1852 – January 30, 1921) was a Canadian lawyer and judge.

Born in Quebec City, Canada East, the son of Lawrence Ambrose Cannon and Mary Jane Cary, his godfather was Augustin-Norbert Morin.

He was called to the Quebec Bar in 1874 and practiced law in Arthabaskaville (Victoriaville) in partnership with Édouard-Louis Pacaud.

In 1882, he ran unsuccessfully as the Liberal candidate for the House of Commons of Canada in the riding of Drummond—Arthabaska losing to Désiré Olivier Bourbeau.

In 1891, he was appointed deputy attorney general and law clerk for the province of Quebec.