10 cities
| City | County | 2025 Pop. ↓ |
|---|---|---|
| Janesville | Rock County | 66,622 |
| Jackson | Washington County | 8,245 |
| Jefferson | Jefferson County | 7,761 |
| Johnson Creek | Jefferson County | 3,412 |
| Juneau | Dodge County | 2,711 |
| Junction City | Portage County | 417 |
| Juda | Green County | 377 |
| Jim Falls | Chippewa County | 214 |
| Jolmaville | Ashland County | 129 |
| Jump River | Taylor County | 69 |