| Castelletto Cervo | |
| Official Name: | Comune di Castelletto Cervo |
| Native Name: | Castlet |
| Coordinates: | 45.4833°N 24°W |
| Region: | Piedmont |
| Province: | Biella (BI) |
| Mayor: | Renzo Selva |
| Area Total Km2: | 15.0 |
| Population Footnotes: | [1] |
| Population Total: | 790 |
| Population As Of: | 31 December 2021 |
| Population Demonym: | Castellettesi |
| Elevation M: | 216 |
| Postal Code: | 13040 |
| Area Code: | 0161 |
Castelletto Cervo is a comune (municipality) in the Province of Biella in the Italian region Piedmont, located about 60km (40miles) northeast of Turin and about 20km (10miles) southeast of Biella.
Castelletto Cervo borders the municipalities of Buronzo, Gifflenga, Lessona, Masserano, and Mottalciata.