13 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Indianola | 1 | 16,405 | 15,863 | 0.66% | 1,435 | 11 | City |
| Norwalk | 2 | 16,015 | 12,917 | 4.02% | 1,375 | 12 | City |
| Carlisle | 3 | 4,434 | 4,169 | 1.21% | 785 | 6 | City |
| Milo | 4 | 758 | 775 | -0.52% | 1,247 | 1 | City |
| Hartford | 5 | 727 | 734 | -0.27% | 668 | 1 | City |
| Cumming | 6 | 550 | 434 | 4.36% | 159 | 3 | City |
| New Virginia | 7 | 498 | 503 | -0.2% | 1,107 | 0 | City |
| Martensdale | 8 | 410 | 422 | -0.73% | 1,079 | 0 | City |
| Lacona | 9 | 334 | 344 | -0.6% | 1,009 | 0 | City |
| Ackworth | 10 | 117 | 116 | 0% | 213 | 1 | City |
| St. Marys | 11 | 116 | 115 | 0% | 823 | 0 | City |
| Spring Hill | 12 | 68 | 65 | 0% | 544 | 0 | City |
| Sandyville | 13 | 59 | 57 | 0% | 119 | 0 | City |
Indianola is the largest city in Warren County, with a population of 16,405.
Sandyville is the smallest city in Warren County, with a population of 59.
There are 13 cities in Warren County, Iowa.