| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density (/mi²) | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Mason City | 1 | 26,749 | 27,280 | -0.39% | 946 | 28 | City |
| Clear Lake | 2 | 7,576 | 7,661 | -0.33% | 703 | 11 | City |
| Rockwell | 3 | 1,031 | 1,068 | -0.77% | 347 | 3 | City |
| Ventura | 4 | 694 | 711 | -0.57% | 391 | 2 | City |
| Thornton | 5 | 388 | 404 | -0.77% | 312 | 1 | City |
| Plymouth | 6 | 362 | 381 | -1.09% | 821 | 0 | City |
| Meservey | 7 | 209 | 219 | -0.95% | 140 | 1 | City |
| Rock Falls | 8 | 141 | 150 | -1.4% | 681 | 0 | City |
| Swaledale | 9 | 135 | 143 | -1.46% | 542 | 0 | City |
| Dougherty | 10 | 57 | 60 | -1.72% | 102 | 1 | City |
Mason City is the largest city in Cerro Gordo County, with a population of 26,749.
Dougherty is the smallest city in Cerro Gordo County, with a population of 57.
There are 10 cities in Cerro Gordo County, Iowa.