8 cities
| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Janesville | 1 | 66,816 | 65,651 | 0.29% | 1,929 | 35 | City |
| Beloit | 2 | 36,589 | 36,721 | -0.06% | 2,110 | 17 | City |
| Edgerton | 3 | 6,234 | 5,945 | 0.78% | 1,499 | 4 | City |
| Evansville | 4 | 5,869 | 5,718 | 0.43% | 1,580 | 4 | City |
| Milton | 5 | 5,812 | 5,709 | 0.29% | 1,251 | 5 | City |
| Clinton | 6 | 2,346 | 2,213 | 0.95% | 1,638 | 1 | Village |
| Orfordville | 7 | 1,662 | 1,469 | 1.96% | 1,400 | 1 | Village |
| Footville | 8 | 929 | 838 | 1.64% | 824 | 1 | Village |
Janesville is the largest city in Rock County, with a population of 66,816.
Footville is the smallest city in Rock County, with a population of 929.
There are 8 cities in Rock County, Wisconsin.