18 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Fort Payne | 1 | 15,053 | 14,871 | 0.24% | 267 | 56 | City |
| Rainsville | 2 | 6,031 | 5,529 | 1.69% | 291 | 21 | City |
| Henagar | 3 | 2,326 | 2,305 | 0.17% | 103 | 23 | City |
| Collinsville | 4 | 2,063 | 2,066 | -0.05% | 617 | 3 | Town |
| Sylvania | 5 | 1,830 | 1,799 | 0.33% | 215 | 9 | Town |
| Crossville | 6 | 1,829 | 1,828 | 0% | 219 | 8 | Town |
| Sardis City | 7 | 1,772 | 1,820 | -0.56% | 225 | 8 | Town |
| Fyffe | 8 | 976 | 973 | 0% | 196 | 5 | Town |
| Powell | 9 | 934 | 909 | 0.54% | 195 | 5 | Town |
| Geraldine | 10 | 911 | 910 | 0% | 238 | 4 | Town |
| Ider | 11 | 740 | 728 | 0.27% | 136 | 5 | Town |
| Valley Head | 12 | 598 | 581 | 0.5% | 158 | 4 | Town |
| Hammondville | 13 | 429 | 423 | 0.23% | 88 | 5 | Town |
| Mentone | 14 | 336 | 323 | 0.6% | 78 | 4 | Town |
| Shiloh | 15 | 332 | 327 | 0.3% | 156 | 2 | Town |
| Pine Ridge | 16 | 269 | 262 | 0.37% | 202 | 1 | Town |
| Lakeview | 17 | 166 | 164 | 0% | 256 | 1 | Town |
| Ridgeville | 18 | 84 | 86 | -1.18% | 102 | 1 | Town |
Fort Payne is the largest city in DeKalb County, with a population of 15,053.
Ridgeville is the smallest city in DeKalb County, with a population of 84.
There are 18 cities in DeKalb County, Alabama.