| Saint-Jean-du-Castillonnais | |
| Commune Status: | Commune |
| Arrondissement: | Saint-Girons |
| Canton: | Couserans Ouest |
| Insee: | 09263 |
| Postal Code: | 09800 |
| Mayor: | Philippe Martin-Lempereur[1] |
| Term: | 2020 - 2026 |
| Coordinates: | 42.9367°N 0.9319°W |
| Elevation M: | 710 |
| Elevation Min M: | 633 |
| Elevation Max M: | 1416 |
| Area Km2: | 4.74 |
Saint-Jean-du-Castillonnais (in French pronounced as /sɛ̃ ʒɑ̃ dy kastijone/; Occitan (post 1500);: Sent Joanh deth Castilhonés) is a commune in the Ariège department in southwestern France.
Inhabitants are called Saint-Jeantois in French.