20 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Eaton | 1 | 8,323 | 8,391 | -0.17% | 1,295 | 6 | City |
| Eaton | 2 | 6,071 | 5,819 | 0.96% | 266 | 23 | Township |
| Gratis | 3 | 4,231 | 4,225 | 0.62% | 116 | 37 | Township |
| Gasper | 4 | 3,933 | 3,918 | 0.69% | 169 | 23 | Township |
| Somers | 5 | 3,850 | 3,826 | 0.71% | 108 | 36 | Township |
| Lanier | 6 | 3,730 | 3,730 | 0.62% | 103 | 36 | Township |
| Twin | 7 | 2,664 | 2,666 | 0.6% | 76 | 35 | Township |
| Camden | 8 | 1,990 | 1,990 | 0% | 1,604 | 1 | Village |
| Washington | 9 | 1,803 | 1,799 | 0.73% | 46 | 40 | Township |
| Lewisburg | 10 | 1,734 | 1,748 | -0.17% | 1,598 | 1 | Village |
| Camden | 11 | 1,525 | 1,497 | 0.86% | 77 | 20 | Township |
| New Paris | 12 | 1,484 | 1,492 | -0.13% | 2,019 | 1 | Village |
| West Alexandria | 13 | 1,314 | 1,327 | -0.23% | 1,510 | 1 | Village |
| Israel | 14 | 1,140 | 1,138 | 0.53% | 32 | 35 | Township |
| Gratis | 15 | 833 | 840 | -0.24% | 859 | 1 | Village |
| Dixon | 16 | 545 | 547 | 0.55% | 15 | 36 | Township |
| Eldorado | 17 | 454 | 457 | -0.22% | 1,983 | 0 | Village |
| West Manchester | 18 | 412 | 417 | -0.24% | 1,515 | 0 | Village |
| Verona | 19 | 400 | 405 | -0.25% | 877 | 0 | Village |
| West Elkton | 20 | 161 | 164 | -0.62% | 276 | 1 | Village |
Eaton is the largest city in Preble County, with a population of 8,323.
West Elkton is the smallest city in Preble County, with a population of 161.
There are 20 cities in Preble County, Ohio.