23 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Center township | 1 | 3,367 | 3,442 | -0.47% | 81 | 41.38 | Township |
| Jerusalem township | 2 | 2,890 | 2,901 | -0.1% | 97 | 29.67 | Township |
| Woodsfield | 3 | 2,146 | 2,205 | -0.56% | 1,065 | 2.02 | Village |
| Sunsbury township | 4 | 1,233 | 1,275 | -0.8% | 43 | 28.42 | Township |
| Malaga township | 5 | 1,034 | 1,049 | -0.19% | 35 | 29.30 | Township |
| Lee township | 6 | 876 | 897 | -0.45% | 50 | 17.41 | Township |
| Ohio township | 7 | 825 | 847 | -0.48% | 36 | 23.11 | Township |
| Matamoras (New Matamoras) | 8 | 679 | 703 | -0.73% | 1,951 | 0.35 | Village |
| Adams township | 9 | 626 | 634 | -0.16% | 28 | 22.47 | Township |
| Summit township | 10 | 576 | 599 | -0.86% | 25 | 23.04 | Township |
| Seneca township | 11 | 420 | 433 | -0.47% | 19 | 22.46 | Township |
| Switzerland township | 12 | 407 | 417 | -0.49% | 15 | 27.20 | Township |
| Washington township | 13 | 403 | 412 | -0.25% | 13 | 30.95 | Township |
| Sardis | 14 | 344 | 629 | -3.91% | 273 | 1.26 | CDP |
| Beallsville | 15 | 343 | 352 | -0.58% | 945 | 0.36 | Village |
| Benton township | 16 | 272 | 279 | -0.37% | 12 | 22.57 | Township |
| Clarington | 17 | 268 | 278 | -0.74% | 234 | 1.14 | Village |
| Lewisville | 18 | 177 | 186 | -1.12% | 477 | 0.37 | Village |
| Jerusalem | 19 | 120 | 124 | -0.83% | 496 | 0.24 | Village |
| Hannibal | 20 | 118 | 295 | -14.49% | 106 | 1.11 | CDP |
| Antioch | 21 | 73 | 75 | 0% | 709 | 0.10 | Village |
| Stafford | 22 | 67 | 69 | 0% | 197 | 0.34 | Village |
| Miltonsburg | 23 | 37 | 39 | 0% | 507 | 0.07 | Village |
Center township is the largest city in Monroe County, with a population of 3,367.
Miltonsburg is the smallest city in Monroe County.
There are 23 cities in Monroe County, Ohio.