Trezzano sul Naviglio is a comune in the Province of Milan in the Italian region Lombardy, located about 9 km southwest of Milan. As of 31 December 2004, it had a population of 18,819 and an area of 10.8 km2.Trezzano sul Naviglio borders the following municipalities: Buccinasco, Cusago, Cesano Boscone, Corsico, Gaggiano, Milan, Zibido San Giacomo. It is served by Trezzano sul Naviglio railway station.