Valle Maggia (English, "Maggia Valley") is an alpine valley in the Vallemaggia district of canton of Ticino, the Italian-speaking canton of Switzerland . The valley is formed by the river Maggia and is situated between the Centovalli and Lago Maggiore as well as the Valle Verzasca in the East.

The Maggia valley has a spatial extension of 569.64 km2 (219.94 sq mi), equal to one-fifth of the canton of Ticino. It is the largest valley of the canton and one of the widest within the Alps' south side. The valley is formed by the river Maggia, whose source is the Cristallina peak in Val Sambuco (Lavizzara). The river runs through the valley down to Ascona, where it pours into the Lake Maggiore .