Le Petit Bras is a tributary of the southwest bank of the lower part of the watercourse Le Gros Bras, flowing in the municipality of Saint-Urbain, in the Charlevoix Regional County Municipality, in the administrative region of Capitale-Nationale, in the province of Quebec, in Canada.

The water level of the river varies with the seasons and the precipitation; the spring flood generally occurs in April.

This mouth is located at: From the mouth of Le Petit Bras, the current descends on 1.9 kilometres (1.2 mi) following the course of Le Gros Bras towards the south-east; then on 25.3 kilometres (15.7 mi) with a drop of 56 metres (184 ft) following the course of the rivière du Gouffre which flows into Baie-Saint-Paul in the St. Lawrence River.

Note: A stream officially named on the sheet 21M / 07, located eight kilometers to the southeast.

The toponym "Le Petit Bras" was formalized on September 22, 1976 at the Place Names Bank of the Commission de toponymie du Québec.