Lac Sept Îles is a freshwater body straddling the municipalities of Saint-Ubalde and Saint-Alban, in the Portneuf Regional County Municipality, in the administrative region of Capitale-Nationale, in the province of Quebec, Canada.

A 360 m strip of land separates it with a bay on the west shore of Lac Montauban.

The mouth of Lac Sept Îles is located at the bottom of a bay in the far west.

Then, this river flows for one kilometer south to Lake Weller (length: 0.84 km oriented southwest) whose shape resembles a drum stick.

The toponym "Lac Sept Îles" was formalized on December 5, 1968, at the Place Names Bank of the Commission de toponymie du Québec.