The Rivière Noire Sud-Ouest (Black River Southwest) is a tributary of the south shore of the Noire River flowing, entirely in the unorganized territory from Mont-Élie in Charlevoix-Est Regional County Municipality, in Quebec, Canada.

The lower part of this valley is served by route 170 which links Saint-Siméon to Petit-Saguenay, which passes on the north shore of the Noire River.

The surface of "rivière Noire Sud-Ouest" is usually frozen from the beginning of December to the end of March, however, safe ice circulation is generally from mid-December to mid-March.

The main hydrographic slopes near the Black River are: The "rivière Noire Sud-Ouest" originates at the mouth of Julie Lake (length: 0.3 km (0.19 mi); altitude: 729 m (2,392 ft)).

The toponym "rivière Noire Sud-Ouest" was formalized on December 5, 1968 at the Bank of place names of the Commission de toponymie du Quebec.