45 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Washington | 1 | 3,419 | 3,530 | -1.21% | 59 | 58.19 | Township |
| Washington | 2 | 2,931 | 2,914 | 0.14% | 89 | 32.86 | Township |
| Washington | 3 | 1,060 | 1,072 | -0.19% | 1,091 | 0.97 | City |
| Hanover | 4 | 927 | 933 | 0% | 26 | 35.70 | Township |
| Hanover | 5 | 686 | 691 | -0.15% | 1,145 | 0.60 | City |
| Linn | 6 | 519 | 516 | 0.58% | 14 | 35.88 | Township |
| Clifton | 7 | 449 | 454 | -0.22% | 1,100 | 0.41 | City |
| Washington | 8 | 448 | 469 | -1.1% | 10 | 44.91 | Township |
| Greenleaf | 9 | 430 | 434 | -0.23% | 12 | 35.81 | Township |
| Linn | 10 | 382 | 387 | -0.26% | 1,127 | 0.34 | City |
| Washington | 11 | 378 | 394 | -0.79% | 11 | 35.91 | Township |
| Clifton | 12 | 369 | 364 | 0.54% | 10 | 36.08 | Township |
| Greenleaf | 13 | 345 | 349 | -0.29% | 763 | 0.45 | City |
| Washington | 14 | 311 | 307 | 0.32% | 9 | 35.29 | Township |
| Clifton | 15 | 306 | 330 | -2.55% | 9 | 35.64 | Township |
| Sherman | 16 | 260 | 261 | 0.39% | 7 | 35.89 | Township |
| Barnes | 17 | 223 | 221 | 0.45% | 6 | 35.86 | Township |
| Farmington | 18 | 177 | 175 | 0.57% | 5 | 36.12 | Township |
| Mill Creek | 19 | 177 | 179 | 0% | 5 | 36.12 | Township |
| Washington | 20 | 170 | 174 | -0.58% | 5 | 34.85 | Township |
| Barnes | 21 | 163 | 163 | 0% | 959 | 0.17 | City |
| Haddam | 22 | 160 | 162 | 0% | 4 | 35.85 | Township |
| Washington | 23 | 148 | 148 | 0.68% | 4 | 36.14 | Township |
| Palmer | 24 | 124 | 124 | 0% | 401 | 0.31 | City |
| Morrowville | 25 | 112 | 116 | -0.88% | 783 | 0.14 | City |
| Strawberry | 26 | 112 | 110 | 0.9% | 3 | 36.13 | Township |
| Sheridan | 27 | 107 | 105 | 0.94% | 3 | 35.91 | Township |
| Haddam | 28 | 106 | 110 | -0.93% | 309 | 0.34 | City |
| Little Blue | 29 | 77 | 77 | 0% | 2 | 35.52 | Township |
| Washington | 30 | 73 | 73 | -1.35% | 1 | 57 | Township |
| Brantford | 31 | 71 | 71 | 0% | 2 | 35.79 | Township |
| Washington | 32 | 66 | 69 | -1.49% | 1 | 46.68 | Township |
| Washington | 33 | 64 | 67 | -1.54% | 1 | 53.70 | Township |
| Charleston | 34 | 63 | 63 | 0% | 2 | 35.45 | Township |
| Coleman | 35 | 61 | 61 | 0% | 2 | 36.15 | Township |
| Union | 36 | 60 | 60 | 0% | 2 | 35.67 | Township |
| Washington | 37 | 57 | 57 | 0% | 2 | 35.92 | Township |
| Washington | 38 | 56 | 57 | 0% | 2 | 35.69 | Township |
| Kimeo | 39 | 50 | 50 | 0% | 1 | 35.91 | Township |
| Hanover | 40 | 49 | 49 | 0% | 1 | 35.96 | Township |
| Lowe | 41 | 47 | 47 | 0% | 1 | 35.42 | Township |
| Grant | 42 | 45 | 45 | 0% | 1 | 35.88 | Township |
| Mahaska | 43 | 43 | 43 | 0% | 193 | 0.22 | City |
| Washington | 44 | 43 | 43 | 0% | 1 | 35.88 | Township |
| Hollenberg | 45 | 13 | 13 | 0% | 178 | 0.07 | City |
Washington is the largest city in Washington County, with a population of 3,419.
Hollenberg is the smallest city in Washington County, with a population of 13.
There are 45 cities in Washington County, Kansas.