11 cities
| City | County | 2026 Pop. ↓ |
|---|---|---|
| Owensboro | Daviess County | 60,870 |
| Oakbrook | Boone County | 9,557 |
| Oak Grove | Christian County | 7,992 |
| Owenton | Owen County | 1,678 |
| Orchard Grass Hills | Jefferson County | 1,646 |
| Owingsville | Bath County | 1,589 |
| Olive Hill | Carter County | 1,509 |
| Old Brownsboro Place | Jefferson County | 383 |
| Oakland | Warren County | 195 |
| Onton | Webster County | 107 |
| Oneida | Clay County | 100 |