25 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Sabetha | 1 | 2,460 | 2,538 | -0.65% | 739 | 3 | City |
| Seneca | 2 | 2,140 | 2,142 | -0.05% | 1,197 | 2 | City |
| Illinois | 3 | 525 | 538 | -0.19% | 15 | 36 | Township |
| Centralia | 4 | 493 | 482 | 0.41% | 1,086 | 0 | City |
| Wetmore | 5 | 457 | 471 | -0.44% | 13 | 36 | Township |
| Rock Creek | 6 | 441 | 457 | -0.45% | 13 | 34 | Township |
| Berwick | 7 | 386 | 398 | -0.52% | 11 | 36 | Township |
| Wetmore | 8 | 336 | 348 | -0.88% | 868 | 0 | City |
| Mitchell | 9 | 301 | 309 | -0.33% | 8 | 36 | Township |
| Harrison | 10 | 300 | 308 | -0.33% | 8 | 36 | Township |
| Corning | 11 | 207 | 214 | -0.96% | 681 | 0 | City |
| Gilman | 12 | 194 | 202 | -1.02% | 5 | 36 | Township |
| Center | 13 | 163 | 169 | -0.61% | 5 | 36 | Township |
| Bern | 14 | 161 | 166 | -0.62% | 567 | 0 | City |
| Adams | 15 | 154 | 164 | -1.91% | 4 | 36 | Township |
| Capioma | 16 | 126 | 129 | 0% | 4 | 36 | Township |
| Nemaha | 17 | 119 | 128 | -2.46% | 3 | 35 | Township |
| Wheaton | 18 | 108 | 98 | 1.89% | 701 | 0 | City |
| Goff | 19 | 102 | 104 | -0.97% | 495 | 0 | City |
| Red Vermillion | 20 | 101 | 104 | 0% | 3 | 36 | Township |
| Neuchatel | 21 | 96 | 100 | -1.03% | 3 | 36 | Township |
| Clear Creek | 22 | 95 | 99 | -1.04% | 3 | 36 | Township |
| Granada | 23 | 90 | 92 | 0% | 3 | 36 | Township |
| Reilly | 24 | 90 | 94 | -1.1% | 3 | 36 | Township |
| Oneida | 25 | 57 | 60 | -1.72% | 248 | 0 | City |
Sabetha is the largest city in Nemaha County, with a population of 2,460.
Oneida is the smallest city in Nemaha County, with a population of 57.
There are 25 cities in Nemaha County, Kansas.