Lenno is a comune (municipality) in the Province of Como in the Italian region Lombardy, located about 60 kilometres (37 mi) north of Milan and about 20 kilometres (12 mi) northeast of Como. As of 31 December 2004, it had a population of 1,800 and an area of 9.6 km².

Lenno borders the following municipalities: Bellagio, Bene Lario, Grandola ed Uniti, Lezzeno, Mezzegra, Ossuccio, Porlezza, Tremezzo.