Valle di Muggio (known as Valle Breggia in Italy) is a valley in the Canton of Ticino , Switzerland , located in the Mendrisio District at the extreme south of Ticino and crossed by the Breggia torrent. Half of its perimeter borders with Italy.

The name comes from the town of Muggio, which is the largest population centre in the valley. Roncapiano is the highest village in the valley, where the roads end. The river Breggia runs through it, before flowing into Italy and Lake Como . The valley comprises the municipality of Castel San Pietro on its right slope and the municipality of Breggia on its left slope.