22 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Cadiz township | 1 | 3,210 | 3,397 | -1.5% | 94 | 34.33 | Township |
| Cadiz | 2 | 2,922 | 3,059 | -0.92% | 333 | 8.78 | Village |
| Harrisville township | 3 | 1,756 | 1,719 | 0.52% | 73 | 24.06 | Township |
| North township | 4 | 1,514 | 1,602 | -1.5% | 65 | 23.19 | Township |
| Rumley township | 5 | 1,225 | 1,279 | -1.13% | 53 | 23.30 | Township |
| Short Creek township | 6 | 962 | 1,015 | -1.54% | 32 | 30.11 | Township |
| Hopedale | 7 | 889 | 924 | -0.78% | 759 | 1.17 | Village |
| Freeport township | 8 | 698 | 734 | -1.41% | 29 | 24.08 | Township |
| German township | 9 | 688 | 719 | -1.29% | 27 | 25.13 | Township |
| Scio | 10 | 641 | 671 | -0.93% | 1,151 | 0.56 | Village |
| Washington township | 11 | 589 | 614 | -1.01% | 19 | 30.33 | Township |
| Jewett | 12 | 529 | 553 | -0.94% | 1,039 | 0.51 | Village |
| Stock township | 13 | 420 | 442 | -1.41% | 17 | 24.61 | Township |
| Moorefield township | 14 | 373 | 390 | -1.32% | 14 | 26.88 | Township |
| Bowerston | 15 | 343 | 358 | -0.87% | 678 | 0.51 | Village |
| Freeport | 16 | 310 | 322 | -0.64% | 518 | 0.60 | Village |
| Nottingham township | 17 | 290 | 299 | -0.68% | 10 | 28.20 | Township |
| Archer township | 18 | 275 | 288 | -1.43% | 11 | 25.18 | Township |
| New Athens | 19 | 209 | 221 | -0.95% | 726 | 0.29 | Village |
| Harrisville | 20 | 170 | 177 | -0.58% | 1,118 | 0.15 | Village |
| Tippecanoe | 21 | 91 | 97 | -2.15% | 169 | 0.54 | CDP |
| Deersville | 22 | 64 | 66 | 0% | 186 | 0.34 | Village |
Cadiz township is the largest city in Harrison County, with a population of 3,210.
Deersville is the smallest city in Harrison County.
There are 22 cities in Harrison County, Ohio.