Saint-Léon-le-Grand (French pronunciation: [sɛ̃ leɔ̃ lə ɡʁɑ̃]) is a parish municipality in Quebec, Canada.

The first settlers arrived in 1896 from Baie-des-Sables, Cap-Chat, Sainte-Félicité, Chicoutimi and Lac Saint-Jean.

In the late 1880s, Jos Néron, François Gagné, Eusèbe Gagnon, Polyte Bouchard, Louis Girard, Henri Desbiens, Achille Potvin, Polyte Bouchard (the great) and Hector Desbiens were the first pioneers of the region.

The municipality was officially founded civilly on August 12, 1903 while the parish was canonically established four years later, on December 9, 1907.

The eponymous parish of Saint-Léon-le-Grand is located in the Roman Catholic Archdiocese of Rimouski and, more specifically, in the pastoral region of La Matapédia.