19 cities
| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Pleasant | 1 | 7,981 | 8,086 | -0.03% | 206 | 39 | Township |
| Kenton | 2 | 7,808 | 7,954 | -0.31% | 1,562 | 5 | City |
| Liberty | 3 | 7,007 | 7,072 | -0.01% | 196 | 36 | Township |
| Ada | 4 | 5,275 | 5,329 | -0.17% | 2,472 | 2 | Village |
| Buck | 5 | 2,329 | 2,335 | 0% | 76 | 31 | Township |
| Hale | 6 | 1,531 | 1,549 | 0.07% | 42 | 36 | Township |
| Dudley | 7 | 1,441 | 1,476 | -0.21% | 39 | 37 | Township |
| Blanchard | 8 | 1,402 | 1,414 | 0% | 58 | 24 | Township |
| Forest | 9 | 1,320 | 1,355 | -0.45% | 789 | 2 | Village |
| McDonald | 10 | 868 | 881 | 0% | 20 | 43 | Township |
| Alger | 11 | 820 | 843 | -0.49% | 2,770 | 0 | Village |
| Dunkirk | 12 | 748 | 772 | -0.53% | 1,137 | 1 | Village |
| Washington | 13 | 705 | 723 | -0.14% | 20 | 36 | Township |
| Roundhead | 14 | 656 | 651 | 0.31% | 25 | 26 | Township |
| Taylor Creek | 15 | 593 | 597 | 0% | 21 | 28 | Township |
| Mount Victory | 16 | 589 | 607 | -0.51% | 698 | 1 | Village |
| Lynn | 17 | 582 | 591 | 0% | 23 | 25 | Township |
| Cessna | 18 | 461 | 470 | 0% | 20 | 23 | Township |
| Ridgeway | 19 | 311 | 317 | -0.32% | 549 | 1 | Village |
Pleasant is the largest city in Hardin County, with a population of 7,981.
Ridgeway is the smallest city in Hardin County, with a population of 311.
There are 19 cities in Hardin County, Ohio.