The Tortue River South-West River (in French: rivière Tortue Sud-Ouest) is a tributary of the west bank of the Tortue River, which flows on the south shore of the St. Lawrence River, east of the village of L'Islet-sur-Mer.

The use of animal names is frequent in French Canadian toponymy to designate watercourses.

The term turtle usually refers to slow current due to the low drop.

The toponym Rivière Tortue Sud-Ouest was made official on December 5, 1968, at the Commission de toponymie du Québec.

This article related to a river in Canada is a stub.