21 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Eaton | 1 | 8,240 | 8,392 | -0.36% | 1,282 | 6.43 | City |
| Eaton township | 2 | 6,039 | 5,840 | 0.6% | 265 | 22.80 | Township |
| Gratis township | 3 | 4,180 | 4,224 | 0% | 114 | 36.58 | Township |
| Gasper township | 4 | 3,880 | 3,917 | 0.03% | 167 | 23.28 | Township |
| Somers township | 5 | 3,797 | 3,825 | 0.08% | 106 | 35.75 | Township |
| Lanier township | 6 | 3,674 | 3,726 | -0.08% | 101 | 36.36 | Township |
| Lake Lakengren | 7 | 3,534 | 3,437 | 0.28% | 1,236 | 2.86 | CDP |
| Twin township | 8 | 2,631 | 2,667 | -0.08% | 75 | 34.89 | Township |
| Camden | 9 | 1,965 | 1,990 | -0.25% | 1,583 | 1.24 | Village |
| Washington township | 10 | 1,769 | 1,797 | -0.17% | 45 | 39.52 | Township |
| Lewisburg | 11 | 1,712 | 1,747 | -0.41% | 1,578 | 1.08 | Village |
| Camden township | 12 | 1,503 | 1,496 | 0.2% | 76 | 19.73 | Township |
| New Paris | 13 | 1,468 | 1,492 | -0.34% | 1,997 | 0.73 | Village |
| West Alexandria | 14 | 1,292 | 1,326 | -0.54% | 1,485 | 0.87 | Village |
| Israel township | 15 | 1,130 | 1,140 | 0% | 32 | 35.42 | Township |
| Gratis | 16 | 824 | 841 | -0.36% | 849 | 0.97 | Village |
| Dixon township | 17 | 538 | 548 | -0.19% | 15 | 35.73 | Township |
| Eldorado | 18 | 449 | 458 | -0.44% | 1,961 | 0.23 | Village |
| West Manchester | 19 | 406 | 416 | -0.49% | 1,493 | 0.27 | Village |
| Verona | 20 | 390 | 400 | -0.51% | 855 | 0.46 | Village |
| West Elkton | 21 | 159 | 163 | -0.63% | 273 | 0.58 | Village |
Eaton is the largest city in Preble County, with a population of 8,240.
West Elkton is the smallest city in Preble County.
There are 21 cities in Preble County, Ohio.