| Castel San Giovanni | |
| Settlement Type: | Frazione |
| Pushpin Map: | Italy |
| Coordinates: | 42.8372°N 12.7067°W |
| Subdivision Type: | Country |
| Subdivision Name: |  Italy |
| Subdivision Type1: | Region |
| Subdivision Name1: | Umbria |
| Subdivision Type2: | Province |
| Subdivision Name2: | Perugia |
| Subdivision Type3: | Italian: [[Comune]] |
| Subdivision Name3: | Castel Ritaldi |
| Elevation Footnotes: | [1] |
| Elevation M: | 225 |
| Population Total: | 259 |
| Population As Of: | 2001 |
| Timezone1: | CET |
| Utc Offset1: | +1 |
| Timezone1 Dst: | CEST |
| Utc Offset1 Dst: | +2 |
| Postal Code Type: | Postcode |
| Postal Code: | 06044 |
| Area Code: | 0743 |
Castel San Giovanni is a frazione of the comune of Castel Ritaldi in the Province of Perugia, Umbria, central Italy. Founded as a castle by Cardinal Gil de Albornoz in 1376, it stands at an elevation of 225 metres above sea level. At the time of the Istat census of 2001 it had 259 inhabitants.