18 cities
| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Bryan | 1 | 8,539 | 8,725 | -0.36% | 1,581 | 5 | City |
| Montpelier | 2 | 3,855 | 3,942 | -0.36% | 1,341 | 3 | Village |
| Center | 3 | 2,883 | 2,942 | -0.14% | 80 | 36 | Township |
| St. Joseph | 4 | 2,632 | 2,645 | 0.19% | 75 | 35 | Township |
| Brady | 5 | 2,563 | 2,617 | -0.16% | 90 | 29 | Township |
| Pulaski | 6 | 2,430 | 2,456 | 0% | 79 | 31 | Township |
| Florence | 7 | 1,925 | 1,948 | 0.05% | 45 | 43 | Township |
| Edgerton | 8 | 1,871 | 1,880 | -0.05% | 1,092 | 2 | Village |
| West Unity | 9 | 1,717 | 1,759 | -0.41% | 1,116 | 2 | Village |
| Bridgewater | 10 | 1,401 | 1,427 | -0.14% | 42 | 33 | Township |
| Pioneer | 11 | 1,396 | 1,429 | -0.36% | 684 | 2 | Village |
| Superior | 12 | 1,288 | 1,318 | -0.16% | 31 | 41 | Township |
| Stryker | 13 | 1,227 | 1,259 | -0.41% | 1,371 | 1 | Village |
| Northwest | 14 | 1,108 | 1,118 | 0% | 34 | 33 | Township |
| Edon | 15 | 781 | 787 | -0.13% | 712 | 1 | Village |
| Mill Creek | 16 | 745 | 759 | -0.13% | 31 | 24 | Township |
| Blakeslee | 17 | 105 | 108 | 0% | 1,117 | 0 | Village |
| Holiday City | 18 | 49 | 51 | 0% | 19 | 3 | Village |
Bryan is the largest city in Williams County, with a population of 8,539.
Holiday City is the smallest city in Williams County, with a population of 49.
There are 18 cities in Williams County, Ohio.