22 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Emporia | 1 | 24,418 | 24,096 | 0.26% | 1,983 | 12 | City |
| Americus | 2 | 1,380 | 1,356 | 0.8% | 16 | 87 | Township |
| Center | 3 | 1,131 | 1,097 | 1.25% | 10 | 119 | Township |
| Jackson | 4 | 974 | 945 | 0.93% | 11 | 87 | Township |
| Emporia | 5 | 964 | 946 | 0.73% | 18 | 52 | Township |
| Fremont | 6 | 859 | 834 | 1.06% | 12 | 71 | Township |
| Pike | 7 | 845 | 810 | 1.2% | 16 | 53 | Township |
| Americus | 8 | 779 | 777 | 0% | 719 | 1 | City |
| Elmendaro | 9 | 754 | 732 | 0.8% | 8 | 99 | Township |
| Olpe | 10 | 531 | 516 | 0.57% | 756 | 1 | City |
| Agnes City | 11 | 426 | 415 | 0.95% | 4 | 107 | Township |
| Reading | 12 | 422 | 411 | 0.96% | 6 | 67 | Township |
| Hartford | 13 | 366 | 355 | 0.55% | 924 | 0 | City |
| Ivy | 14 | 247 | 237 | 1.65% | 7 | 34 | Township |
| Waterloo | 15 | 246 | 234 | 1.65% | 4 | 59 | Township |
| Neosho Rapids | 16 | 240 | 234 | 0.42% | 475 | 1 | City |
| Reading | 17 | 184 | 182 | 0% | 864 | 0 | City |
| Allen | 18 | 166 | 161 | 0.61% | 601 | 0 | City |
| Admire | 19 | 138 | 133 | 0.73% | 427 | 0 | City |
| Allen | 20 | 101 | 111 | -2.88% | 3 | 36 | Township |
| Bushong | 21 | 28 | 28 | 0% | 184 | 0 | City |
| Allen | 22 | 15 | 15 | 0% | 0.00 | 35 | Township |
Emporia is the largest city in Lyon County, with a population of 24,418.
Allen is the smallest city in Lyon County, with a population of 15.
There are 22 cities in Lyon County, Kansas.