51 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Ottawa | 1 | 8,003 | 8,039 | -0.05% | 222 | 36 | Township |
| Ottawa | 2 | 8,003 | 8,029 | -0.05% | 222 | 36 | Township |
| Ottawa | 3 | 4,412 | 4,468 | -0.23% | 970 | 5 | Village |
| Ottawa | 4 | 4,412 | 4,462 | -0.23% | 970 | 5 | Village |
| Pleasant | 5 | 3,732 | 3,792 | -0.08% | 103 | 36 | Township |
| Pleasant | 6 | 3,732 | 3,783 | -0.08% | 103 | 36 | Township |
| Union | 7 | 2,949 | 2,945 | 0.1% | 97 | 30 | Township |
| Union | 8 | 2,949 | 2,945 | 0.1% | 97 | 30 | Township |
| Riley | 9 | 2,185 | 2,235 | -0.5% | 73 | 30 | Township |
| Riley | 10 | 2,185 | 2,231 | -0.5% | 73 | 30 | Township |
| Leipsic | 11 | 2,152 | 2,188 | -0.32% | 584 | 4 | Village |
| Leipsic | 12 | 2,152 | 2,186 | -0.32% | 584 | 4 | Village |
| Columbus Grove | 13 | 2,117 | 2,157 | -0.33% | 1,724 | 1 | Village |
| Columbus Grove | 14 | 2,117 | 2,151 | -0.33% | 1,724 | 1 | Village |
| Monterey | 15 | 2,041 | 2,043 | -0.05% | 83 | 25 | Township |
| Monterey | 16 | 2,041 | 2,041 | -0.05% | 83 | 25 | Township |
| Jennings | 17 | 2,009 | 2,022 | -0.25% | 71 | 28 | Township |
| Jennings | 18 | 2,009 | 2,020 | -0.25% | 71 | 28 | Township |
| Liberty | 19 | 1,661 | 1,673 | -0.24% | 46 | 36 | Township |
| Liberty | 20 | 1,661 | 1,673 | -0.24% | 46 | 36 | Township |
| Kalida | 21 | 1,449 | 1,456 | -0.14% | 862 | 2 | Village |
| Kalida | 22 | 1,449 | 1,456 | -0.14% | 862 | 2 | Village |
| Greensburg | 23 | 1,429 | 1,427 | -0.14% | 47 | 30 | Township |
| Greensburg | 24 | 1,429 | 1,424 | -0.14% | 47 | 30 | Township |
| Blanchard | 25 | 1,198 | 1,228 | -0.42% | 33 | 36 | Township |
| Blanchard | 26 | 1,198 | 1,226 | -0.42% | 33 | 36 | Township |
| Pandora | 27 | 1,183 | 1,200 | -0.25% | 1,110 | 1 | Village |
| Pandora | 28 | 1,183 | 1,198 | -0.25% | 1,110 | 1 | Village |
| Palmer | 29 | 1,181 | 1,157 | 0.6% | 33 | 36 | Township |
| Palmer | 30 | 1,181 | 1,155 | 0.6% | 33 | 36 | Township |
| Sugar Creek | 31 | 1,146 | 1,180 | -0.61% | 38 | 30 | Township |
| Sugar Creek | 32 | 1,146 | 1,178 | -0.61% | 38 | 30 | Township |
| Continental | 33 | 1,081 | 1,101 | -0.37% | 903 | 1 | Village |
| Continental | 34 | 1,081 | 1,099 | -0.37% | 903 | 1 | Village |
| Glandorf | 35 | 983 | 965 | 0.31% | 566 | 2 | Village |
| Glandorf | 36 | 983 | 966 | 0.31% | 566 | 2 | Village |
| Ottoville | 37 | 967 | 965 | 0% | 1,021 | 1 | Village |
| Ottoville | 38 | 967 | 965 | 0% | 1,021 | 1 | Village |
| Fort Jennings | 39 | 531 | 522 | 0.19% | 943 | 1 | Village |
| Fort Jennings | 40 | 531 | 523 | 0.19% | 943 | 1 | Village |
| Dupont | 41 | 205 | 209 | -0.49% | 225 | 1 | Village |
| Dupont | 42 | 205 | 209 | -0.49% | 225 | 1 | Village |
| Cloverdale | 43 | 168 | 171 | -0.59% | 273 | 1 | Village |
| Cloverdale | 44 | 168 | 171 | -0.59% | 273 | 1 | Village |
| Gilboa | 45 | 161 | 168 | -1.23% | 1,229 | 0 | Village |
| Gilboa | 46 | 161 | 168 | -1.23% | 1,229 | 0 | Village |
| Vaughnsville | 47 | 133 | 271 | -6.34% | 778 | 0 | CDP |
| Miller City | 48 | 130 | 133 | -0.76% | 328 | 0 | Village |
| Miller City | 49 | 130 | 133 | -0.76% | 328 | 0 | Village |
| Belmore | 50 | 58 | 60 | -1.69% | 131 | 0 | Village |
| Belmore | 51 | 58 | 60 | -1.69% | 131 | 0 | Village |
Ottawa is the largest city in Putnam County, with a population of 8,003.
Belmore is the smallest city in Putnam County, with a population of 58.
There are 51 cities in Putnam County, Ohio.