22 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Emporia | 1 | 24,113 | 24,093 | 0.02% | 1,958 | 12.31 | City |
| Americus township | 2 | 1,367 | 1,355 | 0.51% | 16 | 86.66 | Township |
| Center township | 3 | 1,128 | 1,099 | 1.08% | 10 | 118.72 | Township |
| Jackson township | 4 | 968 | 946 | 0.83% | 11 | 86.98 | Township |
| Emporia township | 5 | 966 | 950 | 0.73% | 18 | 52.33 | Township |
| Fremont township | 6 | 853 | 832 | 0.95% | 12 | 70.75 | Township |
| Pike township | 7 | 849 | 808 | 1.56% | 16 | 53.38 | Township |
| Americus | 8 | 769 | 776 | -0.13% | 710 | 1.08 | City |
| Elmendaro township | 9 | 755 | 733 | 1.07% | 8 | 98.93 | Township |
| Olpe | 10 | 518 | 517 | 0% | 738 | 0.70 | City |
| Agnes City township | 11 | 424 | 414 | 0.95% | 4 | 107.14 | Township |
| Reading township | 12 | 418 | 410 | 0.72% | 6 | 67.32 | Township |
| Hartford | 13 | 362 | 356 | 0.28% | 914 | 0.40 | City |
| Waterloo township | 14 | 248 | 238 | 1.22% | 4 | 59.17 | Township |
| Ivy township | 15 | 241 | 235 | 0.84% | 7 | 33.77 | Township |
| Neosho Rapids | 16 | 234 | 229 | 0.43% | 463 | 0.51 | City |
| Reading | 17 | 183 | 182 | 0% | 859 | 0.21 | City |
| Allen | 18 | 162 | 161 | 0% | 587 | 0.28 | City |
| Admire | 19 | 132 | 131 | 0% | 409 | 0.32 | City |
| Allen township | 20 | 111 | 113 | 0% | 3 | 36.37 | Township |
| Bushong | 21 | 28 | 28 | 0% | 184 | 0.15 | City |
| Allen township | 22 | 14 | 14 | 0% | 0.00 | 34.82 | Township |
Emporia is the largest city in Lyon County, with a population of 24,113.
Allen township is the smallest city in Lyon County.
There are 22 cities in Lyon County, Kansas.