10 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Onawa | 1 | 2,767 | 2,904 | -1% | 525 | 5 | City |
| Mapleton | 2 | 1,102 | 1,160 | -1.08% | 701 | 2 | City |
| Whiting | 3 | 719 | 748 | -0.83% | 707 | 1 | City |
| Ute | 4 | 322 | 342 | -1.23% | 866 | 0 | City |
| Blencoe | 5 | 221 | 231 | -0.9% | 291 | 1 | City |
| Moorhead | 6 | 183 | 197 | -1.61% | 779 | 0 | City |
| Soldier | 7 | 174 | 183 | -1.14% | 561 | 0 | City |
| Castana | 8 | 102 | 106 | -0.97% | 112 | 1 | City |
| Turin | 9 | 68 | 72 | -1.45% | 756 | 0 | City |
| Rodney | 10 | 43 | 43 | 0% | 283 | 0 | City |
Onawa is the largest city in Monona County, with a population of 2,767.
Rodney is the smallest city in Monona County, with a population of 43.
There are 10 cities in Monona County, Iowa.