The canton Muzillac has 15 communes.
| Code | Name | Population ▼ |
|---|---|---|
| 56143 | Muzillac | 5 089 |
| 56147 | Nivillac | 4 951 |
| 56058 | Férel | 3 499 |
| 56153 | Péaule | 2 929 |
| 56126 | Marzan | 2 684 |
| 56212 | Saint-Dolay | 2 645 |
| 56149 | Noyal-Muzillac | 2 548 |
| 56002 | Ambon | 2 101 |
| 56155 | Pénestin | 2 085 |
| 56052 | Damgan | 1 943 |
| 56004 | Arzal | 1 846 |
| 56030 | Camoël | 1 183 |
| 56018 | Billiers | 1 066 |
| 56077 | Le Guerno | 989 |
| 56195 | La Roche-Bernard | 746 |