18 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Wilmington | 1 | 12,555 | 12,667 | -0.17% | 970 | 13 | City |
| Blanchester | 2 | 4,216 | 4,228 | -0.05% | 1,031 | 4 | Village |
| Richland | 3 | 3,506 | 3,539 | -0.11% | 104 | 34 | Township |
| Union | 4 | 3,154 | 3,139 | 0.22% | 67 | 47 | Township |
| Vernon | 5 | 3,051 | 3,001 | 0.49% | 114 | 27 | Township |
| Shawnee Hills | 6 | 2,665 | 2,589 | 1.25% | 994 | 3 | CDP |
| Sabina | 7 | 2,456 | 2,496 | -0.32% | 2,088 | 1 | Village |
| Washington | 8 | 2,056 | 2,041 | 0.29% | 76 | 27 | Township |
| Adams | 9 | 2,013 | 2,009 | 0.15% | 94 | 21 | Township |
| Clark | 10 | 2,001 | 1,994 | 0.2% | 55 | 37 | Township |
| New Vienna | 11 | 1,092 | 1,111 | -0.36% | 1,362 | 1 | Village |
| Liberty | 12 | 1,083 | 1,078 | 0.19% | 44 | 25 | Township |
| Clarksville | 13 | 535 | 534 | 0% | 1,148 | 0 | Village |
| Corwin | 14 | 533 | 490 | 1.72% | 1,620 | 0 | Village |
| Wilson | 15 | 521 | 520 | 0.19% | 21 | 25 | Township |
| Martinsville | 16 | 401 | 413 | -0.5% | 1,087 | 0 | Village |
| Midland | 17 | 298 | 308 | -0.67% | 837 | 0 | Village |
| Port William | 18 | 219 | 223 | -0.45% | 2,009 | 0 | Village |
Wilmington is the largest city in Clinton County, with a population of 12,555.
Port William is the smallest city in Clinton County, with a population of 219.
There are 18 cities in Clinton County, Ohio.