7 cities
| City | County | 2026 Pop. ↓ |
|---|---|---|
| Orangeburg | Orangeburg County | 13,478 |
| Oak Grove | Lexington County | 12,433 |
| Olympia | Richland County | 1,601 |
| Oakland | Lee County | 825 |
| Olanta | Florence County | 548 |
| Oswego | Lee County | 260 |
| Olar | Bamberg County | 203 |