Menzonio 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, Fusio, Peccia and Prato-Sornico to form a new and larger municipality Lavizzara.
Menzonio is first mentioned in 1364 as Menzone. Until the beginning of the 15th Century, Menzonio and Brontallo formed a single municipality, and together with Bignasco and Cavergno it formed a Vicinanza which was under the jurisdiction of the Lavizzara valley. At the time of the Swiss Confederation rule over Ticino, Menzonio was one of seven villages in the valley. The village church was part of the parish of Cevio until 1513 when it split away to form a parish with Brontallo. In 1655, this parish was dissolved and Menzonio formed its own parish. The Church of SS Giacomo e Filippo was first mentioned in the 15th Century. The current building was built in 1585 and was rebuilt in 1644 and finally in 1905.
In the 17th Century, the population reached its peak and then decreased gradually, initially because of emigration to Italy. Later the residents emigrated to California and finally they moved away from the villages to the cities of Ticino and the rest of Switzerland. For centuries the local economy was dominated by grazing and agriculture. In the 19th Century there was a soapstone quarry and four mills. The road that connects Menzonio with the valley floor, was built in 1949. In 2000, three-quarters of the workforce were commuters.
Menzonio has an area, as of 1997[update], of 10.68 square kilometers (4.12 sq mi). Of this area, 0.23 km2 (0.089 sq mi) or 2.2% is used for agricultural purposes, while 5.84 km2 (2.25 sq mi) or 54.7% is forested. Of the rest of the land, 0.09 km2 (22 acres) or 0.8% is settled (buildings or roads), 0.15 km2 (37 acres) or 1.4% is either rivers or lakes and 4.12 km2 (1.59 sq mi) or 38.6% is unproductive land.