13 cities
| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Defiance | 1 | 17,245 | 17,050 | 0.19% | 1,349 | 13 | City |
| Defiance | 2 | 13,545 | 13,278 | 0.56% | 453 | 30 | Township |
| Noble | 3 | 6,082 | 5,955 | 0.51% | 260 | 23 | Township |
| Hicksville | 4 | 5,021 | 4,889 | 0.56% | 141 | 36 | Township |
| Hicksville | 5 | 3,457 | 3,427 | 0.14% | 1,354 | 3 | Village |
| Richland | 6 | 3,034 | 2,978 | 0.56% | 87 | 35 | Township |
| Washington | 7 | 1,563 | 1,535 | 0.51% | 44 | 36 | Township |
| Mark | 8 | 916 | 887 | 0.33% | 25 | 37 | Township |
| Farmer | 9 | 894 | 892 | 0.34% | 24 | 37 | Township |
| Adams | 10 | 891 | 878 | 0.56% | 25 | 36 | Township |
| Sherwood | 11 | 831 | 804 | 0.61% | 533 | 2 | Village |
| Ney | 12 | 299 | 301 | 0% | 763 | 0 | Village |
| Florida | 13 | 213 | 221 | -0.47% | 947 | 0 | Village |
Defiance is the largest city in Defiance County, with a population of 17,245.
Florida is the smallest city in Defiance County, with a population of 213.
There are 13 cities in Defiance County, Ohio.