| Chastel-Arnaud | |
| Commune Status: | Commune |
| Arrondissement: | Die |
| Canton: | Le Diois |
| Insee: | 26080 |
| Postal Code: | 26340 |
| Mayor: | Frédéric Teyssot[1] |
| Term: | 2020 - 2026 |
| Coordinates: | 44.6636°N 5.2131°W |
| Elevation Min M: | 352 |
| Elevation Max M: | 1539 |
| Area Km2: | 12.65 |
Chastel-Arnaud (in French pronounced as /ʃastɛl aʁno/) is a commune in the Drôme department in southeastern France.