11 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Janesville | 1 | 66,622 | 65,651 | 0.29% | 1,935 | 34 | City |
| Beloit | 2 | 36,611 | 36,721 | -0.06% | 2,111 | 17 | City |
| Edgerton | 3 | 6,186 | 5,945 | 0.78% | 1,487 | 4 | City |
| Evansville | 4 | 5,844 | 5,718 | 0.43% | 1,794 | 3 | City |
| Milton | 5 | 5,795 | 5,709 | 0.29% | 1,247 | 5 | City |
| Clinton | 6 | 2,324 | 2,213 | 0.96% | 1,623 | 1 | Village |
| Orfordville | 7 | 1,630 | 1,469 | 2% | 1,373 | 1 | Village |
| Footville | 8 | 914 | 838 | 1.67% | 810 | 1 | Village |
| Shopiere | 9 | 241 | 200 | 7.11% | 1,111 | 0 | CDP |
| Allens Grove | 10 | 193 | 161 | 7.22% | 337 | 1 | CDP |
| Hanover | 11 | 144 | 119 | -1.37% | 247 | 1 | CDP |
Janesville is the largest city in Rock County, with a population of 66,622.
Hanover is the smallest city in Rock County, with a population of 144.
There are 11 cities in Rock County, Wisconsin.