| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density (/mi²) | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Overland Park | 1 | 204,818 | 197,835 | 0.56% | 2,723 | 75 | City |
| Olathe | 2 | 151,803 | 141,549 | 1.19% | 2,347 | 65 | City |
| Shawnee | 3 | 70,379 | 67,453 | 0.76% | 1,677 | 42 | City |
| Lenexa | 4 | 60,947 | 57,528 | 0.73% | 1,789 | 34 | City |
| Leawood | 5 | 34,109 | 33,874 | 0.05% | 2,258 | 15 | City |
| Gardner | 6 | 26,739 | 23,429 | 2.24% | 1,793 | 15 | City |
| Prairie Village | 7 | 22,993 | 22,962 | -0.07% | 3,702 | 6 | City |
| Merriam | 8 | 11,614 | 11,091 | 0.91% | 2,690 | 4 | City |
| Spring Hill | 9 | 11,273 | 8,192 | 4.6% | 1,133 | 10 | City |
| Mission | 10 | 10,137 | 9,945 | 0.12% | 3,799 | 3 | City |
| De Soto | 11 | 7,185 | 6,154 | 1.44% | 280 | 26 | City |
| Roeland Park | 12 | 6,637 | 6,865 | -0.69% | 4,097 | 2 | City |
| Fairway | 13 | 4,179 | 4,172 | -0.05% | 3,702 | 1 | City |
| Mission Hills | 14 | 3,504 | 3,589 | -0.51% | 1,720 | 2 | City |
| Edgerton | 15 | 1,734 | 1,754 | -0.57% | 200 | 9 | City |
| Westwood | 16 | 1,713 | 1,747 | -0.41% | 4,168 | 0 | City |
| Westwood Hills | 17 | 393 | 402 | -0.51% | 6,141 | 0 | City |
| Mission Woods | 18 | 199 | 202 | -0.5% | 2,236 | 0 | City |
Overland Park is the largest city in Johnson County, with a population of 204,818.
Mission Woods is the smallest city in Johnson County, with a population of 199.
There are 18 cities in Johnson County, Kansas.