| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density (/mi²) | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Janesville | 1 | 67,140 | 65,652 | 0.32% | 1,938 | 35 | City |
| Beloit | 2 | 36,636 | 36,740 | -0.04% | 2,113 | 17 | City |
| Edgerton | 3 | 6,171 | 5,939 | 0.82% | 1,484 | 4 | City |
| Milton | 4 | 6,043 | 5,709 | 0.32% | 1,301 | 5 | City |
| Evansville | 5 | 5,863 | 5,717 | 0.45% | 1,579 | 4 | City |
| Clinton | 6 | 2,359 | 2,214 | 0.98% | 1,647 | 1 | Village |
| Orfordville | 7 | 1,650 | 1,465 | 1.98% | 1,390 | 1 | Village |
| Footville | 8 | 913 | 839 | 1.67% | 809 | 1 | Village |
Janesville is the largest city in Rock County, with a population of 67,140.
Footville is the smallest city in Rock County, with a population of 913.
There are 8 cities in Rock County, Wisconsin.