8 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Rock Rapids | 1 | 2,770 | 2,609 | 1.17% | 658 | 4.21 | City |
| George | 2 | 1,117 | 1,081 | 0.63% | 487 | 2.29 | City |
| Inwood | 3 | 977 | 927 | 1.03% | 689 | 1.42 | City |
| Larchwood | 4 | 966 | 926 | 0.84% | 932 | 1.04 | City |
| Doon | 5 | 658 | 618 | 1.23% | 840 | 0.78 | City |
| Little Rock | 6 | 448 | 438 | 0.45% | 441 | 1.01 | City |
| Lester | 7 | 317 | 296 | 1.28% | 174 | 1.82 | City |
| Alvord | 8 | 219 | 209 | 0.92% | 380 | 0.58 | City |
Rock Rapids is the largest city in Lyon County, with a population of 2,770.
Alvord is the smallest city in Lyon County.
There are 8 cities in Lyon County, Iowa.