17 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Wilmington | 1 | 12,633 | 12,661 | -0.05% | 976 | 13 | City |
| Blanchester | 2 | 4,225 | 4,230 | -0.02% | 1,034 | 4 | Village |
| Richland | 3 | 3,509 | 3,542 | -0.2% | 104 | 34 | Township |
| Union | 4 | 3,147 | 3,140 | 0.06% | 67 | 47 | Township |
| Vernon | 5 | 3,036 | 3,003 | 0.23% | 113 | 27 | Township |
| Sabina | 6 | 2,457 | 2,495 | -0.32% | 2,089 | 1 | Village |
| Washington | 7 | 2,053 | 2,043 | 0.1% | 76 | 27 | Township |
| Adams | 8 | 2,011 | 2,006 | 0.1% | 94 | 21 | Township |
| Clark | 9 | 1,999 | 1,996 | 0.05% | 54 | 37 | Township |
| New Vienna | 10 | 1,092 | 1,115 | -0.46% | 1,362 | 1 | Village |
| Liberty | 11 | 1,081 | 1,078 | 0.19% | 44 | 25 | Township |
| Clarksville | 12 | 536 | 536 | 0% | 1,150 | 0 | Village |
| Corwin | 13 | 533 | 490 | 1.52% | 1,620 | 0 | Village |
| Wilson | 14 | 520 | 520 | 0% | 21 | 25 | Township |
| Martinsville | 15 | 405 | 415 | -0.49% | 1,098 | 0 | Village |
| Midland | 16 | 298 | 307 | -0.67% | 837 | 0 | Village |
| Port William | 17 | 219 | 223 | -0.45% | 2,009 | 0 | Village |
Wilmington is the largest city in Clinton County, with a population of 12,633.
Port William is the smallest city in Clinton County, with a population of 219.
There are 17 cities in Clinton County, Ohio.