Fusio is a village and former municipality in the district of Vallemaggia in the canton of Ticino, Switzerland .

In 2004 the municipality was merged with the other, neighboring municipalities Broglio, Brontallo , Menzonio , Peccia and Prato-Sornico to form a new and larger municipality Lavizzara .

Fusio is first mentioned in 1258 as Fuxio.

The population reached its peak in the 16th–17th century (400–500 inhabitants), but towards the end of the 18th century began a slow decline. This slow decline accelerated dramatically after 1950 because of emigration to the cities. Most of the remaining population is elderly.