Gerenzano is a comune (municipality) in the Province of Varese in the Italian region Lombardy, located about 25 kilometres (16 mi) northwest of Milan and about 25 kilometres (16 mi) southeast of Varese.

Gerenzano borders the following municipalities: Cislago, Rescaldina, Rovello Porro, Saronno, Turate, Uboldo.

Gerenzano is served by train transportation with Gerenzano-Turate station, situated on the line connecting Varese and Laveno Mombello to Milan.

Gerenzano has two public primary schools (one entitled to Pope Giovanni XXIII and one to G.P.

Clerici) and one public middle school (entitled to the Italian scientist Enrico Fermi).