Gaggiano ( or Gasgian ) is a comune (municipality) in the Province of Milan in the Italian region Lombardy, located about southwest of Milan. As of 31 December 2004, it had a population of 8,360 and an area of .
Gaggiano borders the following municipalities: Cusago, Cisliano, Albairate, Trezzano sul Naviglio, Vermezzo, Zibido San Giacomo, Gudo Visconti, Noviglio, Rosate.
Gaggiano is served by Gaggiano railway station.
Gaggiano is twinned with: