The Legendre River (in French: rivière Legendre) is a tributary of the Felton River which flows into the Baie Sauvage to the south of Grand lac Saint François which constitutes the head lake of the Saint-François River.

The course of the Legendre River crosses the territories of the municipalities of Milan and Stornoway, in the Le Granit Regional County Municipality (MRC), in the administrative region of Estrie, on the South Shore of the St. Lawrence River, in Quebec, Canada.

The main neighboring hydrographic slopes of the "Legendre river" are: The Legendre River has its source on the northern slope of a mountain (summit at 550 metres (1,800 ft)) of Milan.

This source is located in a forest zone north of route 214.

The toponym "Rivière Legendre" was officially registered on December 5, 1968, at the Commission de toponymie du Québec.