10 cities
| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Onawa | 1 | 2,740 | 2,904 | -0.98% | 520 | 5 | City |
| Mapleton | 2 | 1,091 | 1,160 | -1% | 694 | 2 | City |
| Whiting | 3 | 713 | 748 | -0.83% | 701 | 1 | City |
| Ute | 4 | 318 | 342 | -1.24% | 855 | 0 | City |
| Blencoe | 5 | 219 | 231 | -0.9% | 288 | 1 | City |
| Moorhead | 6 | 180 | 197 | -1.64% | 766 | 0 | City |
| Soldier | 7 | 172 | 183 | -1.15% | 555 | 0 | City |
| Castana | 8 | 101 | 106 | -0.98% | 111 | 1 | City |
| Turin | 9 | 67 | 72 | -1.47% | 744 | 0 | City |
| Rodney | 10 | 43 | 43 | 0% | 283 | 0 | City |
Onawa is the largest city in Monona County, with a population of 2,740.
Rodney is the smallest city in Monona County, with a population of 43.
There are 10 cities in Monona County, Iowa.