| Fagnano Olona | |
| Official Name: | Comune di Fagnano Olona |
| Coordinates: | 45.6667°N 60°W |
| Region: | Lombardy |
| Province: | Varese (VA) |
| Frazioni: | Bergoro |
| Mayor: | FEDERICO SIMONELLI |
| Area Total Km2: | 8.63 |
| Population Total: | 12.436 |
| Population As Of: | July 2024 |
| Population Demonym: | Fagnanesi (borgo), Bergoresi (frazione) |
| Elevation M: | 265 |
| Istat: | 012067 |
| Saint: | San Gaudenzio (borgo), San Giovanni Battista (frazione) |
| Postal Code: | 21054 |
| Area Code: | 0331 |
Fagnano Olona is a town and comune located in the province of Varese, in the Lombardy region of northern Italy.