10 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Onawa | 1 | 2,756 | 2,906 | -1.08% | 523 | 5.27 | City |
| Mapleton | 2 | 1,099 | 1,161 | -1.08% | 699 | 1.57 | City |
| Whiting | 3 | 715 | 744 | -0.83% | 703 | 1.02 | City |
| Ute | 4 | 322 | 342 | -1.23% | 866 | 0.37 | City |
| Blencoe | 5 | 223 | 233 | -0.89% | 293 | 0.76 | City |
| Moorhead | 6 | 183 | 197 | -1.61% | 779 | 0.23 | City |
| Soldier | 7 | 176 | 185 | -1.12% | 568 | 0.31 | City |
| Castana | 8 | 101 | 105 | -0.98% | 111 | 0.91 | City |
| Turin | 9 | 68 | 72 | -1.45% | 756 | 0.09 | City |
| Rodney | 10 | 41 | 45 | -2.38% | 270 | 0.15 | City |
Onawa is the largest city in Monona County, with a population of 2,756.
Rodney is the smallest city in Monona County.
There are 10 cities in Monona County, Iowa.