| Cartosio | |
| Official Name: | Comune di Cartosio |
| Coordinates: | 44.6°N 33°W |
| Region: | Piedmont |
| Province: | Alessandria (AL) |
| Mayor: | Mario Morena |
| Area Total Km2: | 16.7 |
| Population Footnotes: | [1] |
| Population Total: | 734 |
| Population As Of: | 30 November 2019 |
| Population Demonym: | Cartosiani |
| Elevation M: | 230 |
| Postal Code: | 15015 |
| Area Code: | 0144 |
Cartosio is a comune (municipality) in the Province of Alessandria in the Italian region Piedmont, located about 80km (50miles) southeast of Turin and about 40km (30miles) southwest of Alessandria.
Cartosio borders the following municipalities: Castelletto d'Erro, Cavatore, Malvicino, Melazzo, Montechiaro d'Acqui, Pareto, and Ponzone.