| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density (/mi²) | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Oelwein | 1 | 5,725 | 5,909 | -0.56% | 1,189 | 5 | City |
| West Union | 2 | 2,412 | 2,476 | -0.5% | 878 | 3 | City |
| Fayette | 3 | 1,168 | 1,254 | -1.43% | 780 | 1 | City |
| Elgin | 4 | 667 | 686 | -0.45% | 984 | 1 | City |
| Clermont | 5 | 566 | 577 | -0.35% | 449 | 1 | City |
| Maynard | 6 | 460 | 473 | -0.43% | 475 | 1 | City |
| Hawkeye | 7 | 424 | 439 | -0.7% | 631 | 1 | City |
| Arlington | 8 | 412 | 420 | -0.48% | 411 | 1 | City |
| Waucoma | 9 | 239 | 234 | 0.42% | 511 | 0 | City |
| Wadena | 10 | 202 | 207 | -0.98% | 269 | 1 | City |
| Westgate | 11 | 186 | 189 | -0.53% | 511 | 0 | City |
| St. Lucas | 12 | 165 | 168 | -0.6% | 650 | 0 | City |
| Jackson Junction | 13 | 39 | 37 | 0% | 7.0 | 6 | City |
Oelwein is the largest city in Fayette County, with a population of 5,725.
Jackson Junction is the smallest city in Fayette County, with a population of 39.
There are 13 cities in Fayette County, Iowa.