20 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Pleasant | 1 | 7,983 | 8,086 | -0.03% | 206 | 39 | Township |
| Kenton | 2 | 7,832 | 7,954 | -0.32% | 1,566 | 5 | City |
| Liberty | 3 | 7,008 | 7,072 | -0.01% | 196 | 36 | Township |
| Ada | 4 | 5,284 | 5,329 | -0.17% | 2,476 | 2 | Village |
| Buck | 5 | 2,329 | 2,335 | 0% | 76 | 31 | Township |
| Hale | 6 | 1,530 | 1,549 | 0.07% | 42 | 36 | Township |
| Dudley | 7 | 1,444 | 1,476 | -0.21% | 39 | 37 | Township |
| Blanchard | 8 | 1,402 | 1,414 | 0% | 58 | 24 | Township |
| Forest | 9 | 1,326 | 1,355 | -0.45% | 793 | 2 | Village |
| McDonald | 10 | 868 | 881 | 0% | 20 | 43 | Township |
| Alger | 11 | 824 | 843 | -0.48% | 2,784 | 0 | Village |
| Dunkirk | 12 | 752 | 772 | -0.53% | 1,143 | 1 | Village |
| Washington | 13 | 706 | 723 | -0.14% | 20 | 36 | Township |
| Roundhead | 14 | 654 | 651 | 0.31% | 25 | 26 | Township |
| Taylor Creek | 15 | 593 | 597 | 0% | 21 | 28 | Township |
| Mount Victory | 16 | 592 | 607 | -0.5% | 701 | 1 | Village |
| Lynn | 17 | 582 | 591 | 0% | 23 | 25 | Township |
| Cessna | 18 | 461 | 470 | 0% | 20 | 23 | Township |
| Ridgeway | 19 | 312 | 317 | -0.32% | 551 | 1 | Village |
| Dola | 20 | 135 | 141 | 0% | 162 | 1 | CDP |
Pleasant is the largest city in Hardin County, with a population of 7,983.
Dola is the smallest city in Hardin County, with a population of 135.
There are 20 cities in Hardin County, Ohio.