9 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Gallipolis | 1 | 3,264 | 3,313 | -0.3% | 907 | 3.60 | Village |
| Bidwell | 2 | 1,295 | 872 | 7.11% | 851 | 1.52 | CDP |
| Rio Grande | 3 | 725 | 719 | 0.14% | 527 | 1.38 | Village |
| Miller | 4 | 669 | 539 | 7.21% | 675 | 0.99 | CDP |
| Crown City | 5 | 417 | 426 | -0.48% | 359 | 1.16 | Village |
| Kanauga | 6 | 302 | 98 | 2.72% | 1,045 | 0.29 | CDP |
| Vinton | 7 | 221 | 223 | 0% | 188 | 1.18 | Village |
| Cheshire | 8 | 123 | 125 | 0% | 160 | 0.77 | Village |
| Centerville (Thurman) | 9 | 86 | 88 | 0% | 860 | 0.10 | Village |
Gallipolis is the largest city in Gallia County, with a population of 3,264.
Centerville (Thurman) is the smallest city in Gallia County.
There are 9 cities in Gallia County, Ohio.