| Belcastel-et-Buc | |
| Commune Status: | Commune |
| Image Coat Of Arms: | Blason ville Belcastel-et-Buc 11.svg |
| Arrondissement: | Limoux |
| Canton: | La Région Limouxine |
| Insee: | 11029 |
| Postal Code: | 11580 |
| Mayor: | Anne-Marie Valmigere[1] |
| Term: | 2020 - 2026 |
| Intercommunality: | Limouxin |
| Coordinates: | 43.0386°N 2.3411°W |
| Elevation M: | 490 |
| Elevation Min M: | 273 |
| Elevation Max M: | 802 |
| Area Km2: | 14.15 |
Belcastel-et-Buc (in French pronounced as /bɛlkastɛl e byk/; Occitan (post 1500);: Bèlcastèl e Buc) is a commune in the Aude department in southern France.