12 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Iowa City | 1 | 77,159 | 74,914 | 0.59% | 2,995 | 26 | City |
| Coralville | 2 | 24,364 | 22,336 | 1.69% | 1,923 | 13 | City |
| North Liberty | 3 | 22,254 | 20,503 | 1.6% | 2,336 | 10 | City |
| Tiffin | 4 | 7,212 | 4,624 | 7.72% | 1,689 | 4 | City |
| Solon | 5 | 3,344 | 3,041 | 1.83% | 2,093 | 2 | City |
| Lone Tree | 6 | 1,338 | 1,350 | -0.22% | 1,254 | 1 | City |
| University Heights | 7 | 1,179 | 1,223 | -0.76% | 4,535 | 0 | City |
| Hills | 8 | 923 | 862 | 1.32% | 1,123 | 1 | City |
| Swisher | 9 | 907 | 916 | -0.22% | 971 | 1 | City |
| Shueyville | 10 | 723 | 730 | -0.28% | 388 | 2 | City |
| Oxford | 11 | 714 | 716 | -0.14% | 772 | 1 | City |
| Frytown | 12 | 2 | 47 | -84.62% | 2 | 1 | CDP |
Iowa City is the largest city in Johnson County, with a population of 77,159.
Frytown is the smallest city in Johnson County, with a population of 2.
There are 12 cities in Johnson County, Iowa.