6 cities
| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Mount Vernon | 1 | 17,462 | 17,063 | 0.39% | 1,760 | 10 | City |
| Fredericktown | 2 | 2,662 | 2,650 | 0.08% | 1,342 | 2 | Village |
| Gambier | 3 | 2,397 | 2,219 | 1.27% | 2,558 | 1 | Village |
| Centerburg | 4 | 1,700 | 1,703 | 0% | 1,758 | 1 | Village |
| Danville | 5 | 1,000 | 1,017 | -0.3% | 1,692 | 1 | Village |
| Martinsburg | 6 | 222 | 224 | 0% | 1,254 | 0 | Village |
Mount Vernon is the largest city in Knox County, with a population of 17,462.
Martinsburg is the smallest city in Knox County, with a population of 222.
There are 6 cities in Knox County, Ohio.