10 cities
| City | County | 2025 Pop. ↓ |
|---|---|---|
| Owensboro | Daviess County | 60,772 |
| Oakbrook | Boone County | 10,297 |
| Oak Grove | Christian County | 7,982 |
| Owenton | Owen County | 1,680 |
| Orchard Grass Hills | Jefferson County | 1,628 |
| Owingsville | Bath County | 1,589 |
| Olive Hill | Carter County | 1,521 |
| Old Brownsboro Place | Jefferson County | 381 |
| Oneida | Clay County | 234 |
| Oakland | Warren County | 195 |