| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density (/mi²) | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Lancaster | 1 | 42,234 | 40,639 | 0.66% | 2,218 | 19 | City |
| Pickerington | 2 | 26,992 | 23,227 | 2.5% | 2,648 | 10 | City |
| South Bloomfield | 3 | 4,565 | 2,147 | 9.63% | 1,141 | 4 | Village |
| Baltimore | 4 | 3,124 | 3,040 | 0.45% | 1,323 | 2 | Village |
| Lithopolis | 5 | 3,096 | 2,177 | 4.28% | 1,366 | 2 | Village |
| Bremen | 6 | 1,537 | 1,491 | 0.59% | 1,785 | 1 | Village |
| Millersport | 7 | 1,012 | 978 | 0.4% | 1,088 | 1 | Village |
| Pleasantville | 8 | 966 | 943 | 0.21% | 3,565 | 0 | Village |
| Amanda | 9 | 683 | 666 | 0.44% | 2,155 | 0 | Village |
| Thurston | 10 | 617 | 608 | 0.16% | 1,527 | 0 | Village |
| Stoutsville | 11 | 582 | 579 | 0% | 503 | 1 | Village |
| Carroll | 12 | 504 | 502 | 0% | 801 | 1 | Village |
| Sugar Grove | 13 | 412 | 409 | -0.24% | 1,342 | 0 | Village |
| Rushville | 14 | 307 | 305 | 0% | 1,279 | 0 | Village |
| Darbyville | 15 | 189 | 185 | 0% | 366 | 1 | Village |
| West Rushville | 16 | 164 | 165 | -0.61% | 2,523 | 0 | Village |
Lancaster is the largest city in Fairfield County, with a population of 42,234.
West Rushville is the smallest city in Fairfield County, with a population of 164.
There are 16 cities in Fairfield County, Ohio.