11 cities
| City | Parish | 2025 Pop. ↓ |
|---|---|---|
| Opelousas | St. Landry Parish | 15,131 |
| Oak Hills Place | East Baton Rouge Parish | 8,968 |
| Old Jefferson | East Baton Rouge Parish | 8,458 |
| Oakdale | Allen Parish | 6,281 |
| Ossun | Lafayette Parish | 2,645 |
| Oak Grove | West Carroll Parish | 1,329 |
| Olla | LaSalle Parish | 1,297 |
| Oberlin | Allen Parish | 1,289 |
| Oil City | Caddo Parish | 850 |
| Oretta | Beauregard Parish | 813 |
| Oak Ridge | Morehouse Parish | 110 |