Bréal-sous-Montfort (French pronunciation: [bʁeal su mɔ̃fɔʁ], literally Bréal under Montfort; Gallo: Beréau, Breton: Breal-Moñforzh) is a commune in the Ille-et-Vilaine department in the region in Brittany in northwestern France.

It is located in the outer southwest district of Rennes, near the Broceliand woods.

The Meu forms the commune's northeastern border.

Inhabitants of Bréal-sous-Montfort are called Bréalais in French.

This Ille-et-Vilaine geographical article is a stub.