20 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Gallipolis township | 1 | 4,665 | 4,745 | -0.28% | 464 | 10.05 | Township |
| Gallipolis | 2 | 3,264 | 3,313 | -0.31% | 907 | 3.60 | Village |
| Addison township | 3 | 2,085 | 2,113 | -0.24% | 78 | 26.83 | Township |
| Raccoon township | 4 | 2,026 | 2,041 | -0.05% | 55 | 37.06 | Township |
| Clay township | 5 | 1,717 | 1,749 | -0.29% | 78 | 21.90 | Township |
| Huntington township | 6 | 1,444 | 1,442 | 0.14% | 40 | 36.51 | Township |
| Morgan township | 7 | 1,339 | 1,356 | -0.15% | 43 | 30.97 | Township |
| Bidwell | 8 | 1,295 | 872 | 7.11% | 851 | 1.52 | CDP |
| Guyan township | 9 | 1,120 | 1,129 | -0.09% | 36 | 31.54 | Township |
| Walnut township | 10 | 994 | 1,003 | -0.1% | 24 | 40.89 | Township |
| Ohio township | 11 | 924 | 929 | -0.11% | 40 | 23.32 | Township |
| Cheshire township | 12 | 908 | 914 | 0% | 30 | 30.33 | Township |
| Rio Grande | 13 | 725 | 719 | 0.14% | 527 | 1.38 | Village |
| Miller | 14 | 669 | 539 | 7.21% | 675 | 0.99 | CDP |
| Vinton township | 15 | 497 | 506 | -0.2% | 14 | 36.72 | Township |
| Crown City | 16 | 417 | 426 | -0.48% | 359 | 1.16 | Village |
| Kanauga | 17 | 302 | 98 | 2.72% | 1,045 | 0.29 | CDP |
| Vinton | 18 | 221 | 223 | 0% | 188 | 1.18 | Village |
| Cheshire | 19 | 123 | 125 | 0% | 160 | 0.77 | Village |
| Centerville (Thurman) | 20 | 86 | 88 | 0% | 860 | 0.10 | Village |
Gallipolis township is the largest city in Gallia County, with a population of 4,665.
Centerville (Thurman) is the smallest city in Gallia County.
There are 20 cities in Gallia County, Ohio.