| Castillon-de-Saint-Martory | |
| Commune Status: | Commune |
| Arrondissement: | Saint-Gaudens |
| Canton: | Bagnères-de-Luchon |
| Insee: | 31124 |
| Postal Code: | 31360 |
| Mayor: | Patrick Sudre[1] |
| Term: | 2020 - 2026 |
| Intercommunality: | Cagire Garonne Salat |
| Coordinates: | 43.1353°N 0.8597°W |
| Elevation M: | 400 |
| Elevation Min M: | 283 |
| Elevation Max M: | 488 |
| Area Km2: | 10.98 |
Castillon-de-Saint-Martory (in French pronounced as /kastijɔ̃ də sɛ̃ maʁtɔʁi/; Occitan (post 1500);: Castilhon de Sent Martòri) is a commune in the Haute-Garonne department in the Occitanie region in southwestern France.