| Plachy-Buyon | |
| Commune Status: | Commune |
| Image Coat Of Arms: | Blason Ville Fr Plachy-Buyon (Somme).svg |
| Arrondissement: | Amiens |
| Canton: | Ailly-sur-Noye |
| Insee: | 80627 |
| Postal Code: | 80160 |
| Mayor: | Jean-Luc Huyon[1] |
| Term: | 2020 - 2026 |
| Intercommunality: | CC Somme Sud-Ouest |
| Coordinates: | 49.8164°N 2.2197°W |
| Elevation M: | 40 |
| Elevation Min M: | 37 |
| Elevation Max M: | 122 |
| Area Km2: | 10.13 |
Plachy-Buyon (in French pronounced as /plaʃi bɥijɔ̃/; Plachy-Bion) is a commune in the Somme department in Hauts-de-France in northern France.
The commune is situated on the D8 road, some 8miles south of Amiens, in the valley of the Selle river, a tributary of the Somme. It is heavily influenced by the proximity of Amiens.28% of the inhabitants are under the age of twenty.