11 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Ellensburg | 1 | 18,233 | 19,385 | -1.25% | 2,191 | 8.32 | City |
| Terrace Heights | 2 | 10,492 | 8,917 | 2.31% | 998 | 10.52 | CDP |
| Union Gap | 3 | 6,365 | 6,549 | -0.58% | 1,141 | 5.58 | City |
| Cle Elum | 4 | 2,233 | 2,178 | 0.5% | 497 | 4.49 | City |
| Kittitas | 5 | 1,435 | 1,444 | -0.14% | 1,837 | 0.78 | City |
| Roslyn | 6 | 951 | 958 | -0.11% | 217 | 4.39 | City |
| South Cle Elum | 7 | 554 | 559 | -0.18% | 1,378 | 0.40 | Town |
| Snoqualmie Pass | 8 | 447 | 395 | 2.05% | 153 | 2.92 | CDP |
| Easton | 9 | 290 | 302 | -4.29% | 90 | 3.21 | CDP |
| Ronald | 10 | 237 | 202 | -2.07% | 256 | 0.93 | CDP |
| Thorp | 11 | 52 | 109 | -20% | 43 | 1.22 | CDP |
Ellensburg is the largest city in Kittitas County, with a population of 18,233.
Thorp is the smallest city in Kittitas County.
There are 11 cities in Kittitas County, Washington.