22 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Bryan | 1 | 8,531 | 8,725 | -0.46% | 1,580 | 5.40 | City |
| Montpelier | 2 | 3,852 | 3,936 | -0.44% | 1,340 | 2.87 | Village |
| Center township | 3 | 2,890 | 2,941 | -0.17% | 80 | 36.06 | Township |
| St. Joseph township | 4 | 2,620 | 2,643 | 0.08% | 75 | 34.96 | Township |
| Brady township | 5 | 2,572 | 2,617 | -0.16% | 90 | 28.62 | Township |
| Pulaski township | 6 | 2,414 | 2,456 | -0.17% | 79 | 30.63 | Township |
| Florence township | 7 | 1,923 | 1,952 | -0.05% | 45 | 42.91 | Township |
| Edgerton | 8 | 1,858 | 1,878 | -0.21% | 1,084 | 1.71 | Village |
| West Unity | 9 | 1,722 | 1,761 | -0.46% | 1,119 | 1.54 | Village |
| Bridgewater township | 10 | 1,407 | 1,427 | -0.07% | 42 | 33.43 | Township |
| Pioneer | 11 | 1,398 | 1,428 | -0.43% | 685 | 2.04 | Village |
| Superior township | 12 | 1,283 | 1,318 | -0.47% | 31 | 40.95 | Township |
| Stryker | 13 | 1,230 | 1,257 | -0.4% | 1,374 | 0.90 | Village |
| Northwest township | 14 | 1,104 | 1,118 | -0.09% | 34 | 32.62 | Township |
| Edon | 15 | 782 | 792 | -0.26% | 713 | 1.10 | Village |
| Mill Creek township | 16 | 739 | 755 | -0.27% | 31 | 24.15 | Township |
| Lake Seneca | 17 | 675 | 656 | 2.12% | 475 | 1.42 | CDP |
| Nettle Lake | 18 | 232 | 301 | 6.91% | 910 | 0.26 | CDP |
| Kunkle | 19 | 217 | 352 | -0.91% | 775 | 0.28 | CDP |
| Alvordton | 20 | 121 | 247 | -4.72% | 480 | 0.25 | CDP |
| Blakeslee | 21 | 101 | 105 | -0.98% | 1,074 | 0.09 | Village |
| Holiday City | 22 | 49 | 51 | 0% | 19 | 2.55 | Village |
Bryan is the largest city in Williams County, with a population of 8,531.
Holiday City is the smallest city in Williams County.
There are 22 cities in Williams County, Ohio.