14 cities
| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Ottawa | 1 | 4,402 | 4,462 | -0.23% | 968 | 5 | Village |
| Leipsic | 2 | 2,145 | 2,186 | -0.33% | 582 | 4 | Village |
| Columbus Grove | 3 | 2,110 | 2,151 | -0.33% | 1,718 | 1 | Village |
| Kalida | 4 | 1,448 | 1,456 | -0.07% | 861 | 2 | Village |
| Pandora | 5 | 1,180 | 1,198 | -0.25% | 1,107 | 1 | Village |
| Continental | 6 | 1,078 | 1,099 | -0.28% | 901 | 1 | Village |
| Glandorf | 7 | 987 | 966 | 0.41% | 568 | 2 | Village |
| Ottoville | 8 | 968 | 965 | 0.1% | 1,022 | 1 | Village |
| Fort Jennings | 9 | 533 | 523 | 0.38% | 947 | 1 | Village |
| Dupont | 10 | 204 | 209 | -0.49% | 223 | 1 | Village |
| Cloverdale | 11 | 168 | 171 | 0% | 273 | 1 | Village |
| Gilboa | 12 | 160 | 168 | -0.62% | 1,221 | 0 | Village |
| Miller City | 13 | 130 | 133 | 0% | 328 | 0 | Village |
| Belmore | 14 | 58 | 60 | 0% | 131 | 0 | Village |
Ottawa is the largest city in Putnam County, with a population of 4,402.
Belmore is the smallest city in Putnam County, with a population of 58.
There are 14 cities in Putnam County, Ohio.