9 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Oskaloosa | 1 | 11,388 | 11,537 | -0.26% | 1,415 | 8.05 | City |
| New Sharon | 2 | 1,239 | 1,258 | -0.32% | 1,319 | 0.94 | City |
| Fremont | 3 | 677 | 697 | -0.59% | 637 | 1.06 | City |
| University Park | 4 | 467 | 486 | -0.85% | 600 | 0.78 | City |
| Beacon | 5 | 429 | 434 | -0.23% | 552 | 0.78 | City |
| Rose Hill | 6 | 155 | 160 | -0.64% | 1,092 | 0.14 | City |
| Barnes City | 7 | 149 | 154 | -0.67% | 253 | 0.59 | City |
| Leighton | 8 | 146 | 155 | -1.35% | 1,570 | 0.09 | City |
| Keomah Village | 9 | 107 | 111 | -0.93% | 1,698 | 0.06 | City |
Oskaloosa is the largest city in Mahaska County, with a population of 11,388.
Keomah Village is the smallest city in Mahaska County.
There are 9 cities in Mahaska County, Iowa.