The Bras à Pierre is a tributary of the Saint-Jean river, flowing in the municipality of L'Anse-Saint-Jean, in the Le Fjord-du-Saguenay Regional County Municipality, in the administrative region of Saguenay–Lac-Saint-Jean, in the province from Quebec, to Canada.

The surface of "Bras à Pierre" is usually frozen from the beginning of December to the end of March, however the safe circulation on the ice is generally done from mid-December to mid-March.

The main watersheds neighboring the "Bras à Pierre" are: The "Bras à Pierre" originates in the marsh area (length: 2.7 km (1.7 mi); maximum width: 0.4 km (0.25 mi))) between the mountains in the northern part of the Rivière à la Catin.

This source of the watercourse is located at: From the mouth of its source, the course of "Bras à Pierre" descends on 9.0 km (5.6 mi), according to a drop in level of 194 m (636 ft) according to the following segments: Pierre's arm spills out onto the south bank of the Saint-Jean River.

The toponym "Bras à Pierre" was formalized on December 5, 1968, by the Commission de toponymie du Québec.