14 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Port Clinton | 1 | 5,877 | 6,017 | -0.47% | 2,758 | 2.13 | City |
| Ballville | 2 | 3,800 | 3,537 | 1.47% | 840 | 4.52 | CDP |
| Oak Harbor | 3 | 2,785 | 2,820 | -0.25% | 1,755 | 1.59 | Village |
| Genoa | 4 | 2,172 | 2,224 | -0.46% | 1,361 | 1.60 | Village |
| Stony Prairie | 5 | 1,835 | 1,632 | 2.06% | 1,144 | 1.60 | CDP |
| Curtice | 6 | 1,495 | 1,251 | -0.13% | 406 | 3.68 | CDP |
| Elmore | 7 | 1,359 | 1,396 | -0.51% | 1,469 | 0.93 | Village |
| Marblehead | 8 | 831 | 851 | -0.48% | 262 | 3.17 | Village |
| Lakeside | 9 | 561 | 686 | -1.58% | 815 | 0.69 | CDP |
| Williston | 10 | 323 | 419 | -3.29% | 529 | 0.61 | CDP |
| Rocky Ridge | 11 | 306 | 310 | -0.33% | 305 | 1 | Village |
| Clay Center | 12 | 245 | 260 | -1.21% | 242 | 1.01 | Village |
| Put-in-Bay | 13 | 149 | 153 | -0.67% | 339 | 0.44 | Village |
| Wightmans Grove | 14 | 20 | 40 | 5.26% | 142 | 0.14 | CDP |
Port Clinton is the largest city in Ottawa County, with a population of 5,877.
Wightmans Grove is the smallest city in Ottawa County.
There are 14 cities in Ottawa County, Ohio.