The Port-au-Saumon River is a tributary of the northwest shore of the St. Lawrence River, flowing into the town of La Malbaie, into the Charlevoix-Est Regional County Municipality, in the Capitale-Nationale administrative region, Quebec, Canada.

The lower part of the valley of this watercourse is served by route 138 which runs along the northwest shore of the St. Lawrence River and by the road of the rang Sainte-Anne.

The "chemin des érables" and Port-au-Saumon Lake Road serve the upper reaches of this stream.

From the mouth of Port-au-Saumon Lake, the course of the Port-au-Saumon River descends by traveling 20.8 km (12.9 mi) according to the following segments: Upper part of the Port au Saumon River (segment of 15.1 km (9.4 mi)) Lower part of the Port au Saumon River (segment of 5.7 km (3.5 mi)) The French toponym "Port-au-Saumon" is linked to the bay, the hamlet, the river and the lake.

The toponym "Port-au-Saumon River" was formalized on December 5, 1968, at the Bank of place names of the Commission de toponymie du Quebec.