17 cities
| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Gallipolis | 1 | 4,663 | 4,751 | -0.19% | 464 | 10 | Township |
| Gallipolis | 2 | 3,263 | 3,319 | -0.28% | 907 | 4 | Village |
| Addison | 3 | 2,079 | 2,114 | -0.24% | 77 | 27 | Township |
| Raccoon | 4 | 2,030 | 2,044 | -0.1% | 55 | 37 | Township |
| Clay | 5 | 1,714 | 1,750 | -0.35% | 78 | 22 | Township |
| Huntington | 6 | 1,443 | 1,444 | -0.07% | 40 | 37 | Township |
| Morgan | 7 | 1,327 | 1,356 | -0.38% | 43 | 31 | Township |
| Guyan | 8 | 1,113 | 1,125 | -0.18% | 35 | 32 | Township |
| Walnut | 9 | 972 | 991 | -0.31% | 24 | 41 | Township |
| Ohio | 10 | 907 | 928 | -0.33% | 39 | 23 | Township |
| Cheshire | 11 | 891 | 912 | -0.34% | 29 | 30 | Township |
| Rio Grande | 12 | 726 | 720 | 0.14% | 528 | 1 | Village |
| Vinton | 13 | 510 | 509 | 0.59% | 14 | 37 | Township |
| Crown City | 14 | 414 | 422 | -0.24% | 357 | 1 | Village |
| Vinton | 15 | 223 | 223 | 0% | 189 | 1 | Village |
| Cheshire | 16 | 120 | 123 | 0% | 156 | 1 | Village |
| Centerville (Thurman) | 17 | 86 | 88 | 0% | 860 | 0 | Village |
Gallipolis is the largest city in Gallia County, with a population of 4,663.
Centerville (Thurman) is the smallest city in Gallia County, with a population of 86.
There are 17 cities in Gallia County, Ohio.