| Ploumilliau | |
| Native Name: | Plouilio |
| Commune Status: | Commune |
| Image Coat Of Arms: | Blason de la ville de Ploumilliau (Côtes-d'Armor).svg |
| Coordinates: | 48.6808°N -3.5228°W |
| Insee: | 22226 |
| Postal Code: | 22300 |
| Arrondissement: | Lannion |
| Canton: | Plestin-les-Grèves |
| Mayor: | Yann Kergoat[1] |
| Term: | 2020 - 2026 |
| Intercommunality: | Lannion-Trégor Communauté |
| Elevation Min M: | 0 |
| Elevation Max M: | 133 |
| Area Km2: | 34.69 |
Ploumilliau (in French pronounced as /plumijo/;) is a commune in the Côtes-d'Armor department of Brittany in northwestern France.
Inhabitants of Ploumilliau are called milliautais in French.
The municipality launched a linguistic plan through Ya d'ar brezhoneg on 12 December 2006.