8 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Rock Rapids | 1 | 2,733 | 2,612 | 0.89% | 649 | 4 | City |
| George | 2 | 1,113 | 1,078 | 0.63% | 485 | 2 | City |
| Inwood | 3 | 971 | 926 | 0.94% | 685 | 1 | City |
| Larchwood | 4 | 961 | 926 | 0.73% | 927 | 1 | City |
| Doon | 5 | 646 | 614 | 0.94% | 825 | 1 | City |
| Little Rock | 6 | 448 | 441 | 0.22% | 441 | 1 | City |
| Lester | 7 | 312 | 296 | 0.97% | 171 | 2 | City |
| Alvord | 8 | 218 | 207 | 0.93% | 378 | 1 | City |
Rock Rapids is the largest city in Lyon County, with a population of 2,733.
Alvord is the smallest city in Lyon County, with a population of 218.
There are 8 cities in Lyon County, Iowa.