20 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Junction City | 1 | 21,829 | 22,932 | -1.02% | 1,891 | 12 | City |
| Junction City | 2 | 21,829 | 22,949 | -1.02% | 1,891 | 12 | City |
| Smoky Hill | 3 | 9,055 | 9,212 | 1.23% | 168 | 54 | Township |
| Smoky Hill | 4 | 9,055 | 9,219 | 1.23% | 168 | 54 | Township |
| Fort Riley | 5 | 8,839 | 8,720 | 0.82% | 1,379 | 6 | CDP |
| Jefferson | 6 | 2,085 | 2,138 | 0.68% | 44 | 47 | Township |
| Jefferson | 7 | 2,085 | 2,141 | 0.68% | 44 | 47 | Township |
| Milford | 8 | 1,612 | 1,632 | 1.26% | 41 | 40 | Township |
| Milford | 9 | 1,612 | 1,633 | 1.26% | 41 | 40 | Township |
| Milford | 10 | 390 | 407 | -1.02% | 682 | 1 | City |
| Milford | 11 | 390 | 407 | -1.02% | 682 | 1 | City |
| Lyon | 12 | 274 | 280 | 1.11% | 6 | 43 | Township |
| Lyon | 13 | 274 | 280 | 1.11% | 6 | 43 | Township |
| Wingfield | 14 | 178 | 184 | 0.56% | 4 | 47 | Township |
| Wingfield | 15 | 178 | 184 | 0.56% | 4 | 47 | Township |
| Blakely | 16 | 106 | 109 | 0.95% | 3 | 36 | Township |
| Blakely | 17 | 106 | 109 | 0.95% | 3 | 36 | Township |
| Jackson | 18 | 73 | 72 | 2.82% | 2 | 40 | Township |
| Jackson | 19 | 73 | 72 | 2.82% | 2 | 40 | Township |
| Zeandale | 20 | 34 | 62 | 6.25% | 25 | 1 | CDP |
Junction City is the largest city in Geary County, with a population of 21,829.
Zeandale is the smallest city in Geary County, with a population of 34.
There are 20 cities in Geary County, Kansas.