9 cities
| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Cadiz | 1 | 2,898 | 3,054 | -0.89% | 330 | 9 | Village |
| Hopedale | 2 | 886 | 924 | -0.67% | 756 | 1 | Village |
| Scio | 3 | 634 | 670 | -0.94% | 1,138 | 1 | Village |
| Jewett | 4 | 522 | 552 | -0.95% | 1,026 | 1 | Village |
| Bowerston | 5 | 342 | 359 | -0.87% | 676 | 1 | Village |
| Freeport | 6 | 308 | 322 | -0.65% | 514 | 1 | Village |
| New Athens | 7 | 208 | 220 | -0.95% | 722 | 0 | Village |
| Harrisville | 8 | 170 | 178 | -0.58% | 1,118 | 0 | Village |
| Deersville | 9 | 63 | 66 | 0% | 183 | 0 | Village |
Cadiz is the largest city in Harrison County, with a population of 2,898.
Deersville is the smallest city in Harrison County, with a population of 63.
There are 9 cities in Harrison County, Ohio.