Mairengo is a former municipality in the district of Leventina in the canton of Ticino in Switzerland . On 1 April 2012, it was incorporated into the municipality of Faido along with the former municipalities of Anzonico , Calpiogna , Campello, Cavagnago , Chironico and Osco.

Mairengo is first mentioned in 1201 as Mairencho. During the Middle Ages the village belonged to the Degagna of Tarnolgio, which was part of the Vicinanza of Faido. Their annual meetings took place alternately, twice in Mairengo and once in Faido.

The parish of Mairengo also included Faido, Osco, Calpiogna and Campello.