The canton Seignanx has 8 communes.
| Code | Name | Population ▼ |
|---|---|---|
| 40312 | Tarnos | 12 957 |
| 40209 | Ondres | 6 533 |
| 40273 | Saint-Martin-de-Seignanx | 6 238 |
| 40248 | Saint-André-de-Seignanx | 1 945 |
| 40044 | Biaudos | 1 041 |
| 40268 | Saint-Laurent-de-Gosse | 745 |
| 40251 | Saint-Barthélemy | 412 |
| 40042 | Biarrotte | 347 |