21 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Charleston township | 1 | 18,828 | 19,296 | -0.58% | 507 | 37.16 | Township |
| Charleston | 2 | 16,884 | 17,244 | -0.42% | 1,899 | 8.89 | City |
| Mattoon | 3 | 16,365 | 16,852 | -0.59% | 1,587 | 10.31 | City |
| Mattoon township | 4 | 14,165 | 14,610 | -0.68% | 392 | 36.15 | Township |
| Lafayette township | 5 | 4,589 | 4,719 | -0.63% | 127 | 36.19 | Township |
| East Oakland township | 6 | 1,195 | 1,227 | -0.58% | 30 | 39.31 | Township |
| Humboldt township | 7 | 1,175 | 1,208 | -0.59% | 22 | 53.49 | Township |
| Pleasant Grove township | 8 | 1,173 | 1,203 | -0.51% | 28 | 41.70 | Township |
| Ashmore township | 9 | 1,105 | 1,142 | -0.72% | 21 | 53.55 | Township |
| North Okaw township | 10 | 967 | 998 | -0.62% | 18 | 54.39 | Township |
| Paradise township | 11 | 953 | 976 | -0.63% | 41 | 23.27 | Township |
| Hutton township | 12 | 749 | 773 | -0.79% | 14 | 54.58 | Township |
| Oakland | 13 | 715 | 734 | -0.56% | 913 | 0.78 | City |
| Ashmore | 14 | 619 | 638 | -0.64% | 769 | 0.81 | Village |
| Humboldt | 15 | 350 | 360 | -0.57% | 1,020 | 0.34 | Village |
| Seven Hickory township | 16 | 302 | 310 | -0.66% | 6 | 52.04 | Township |
| Morgan township | 17 | 287 | 298 | -1.03% | 11 | 26.43 | Township |
| Lerna | 18 | 216 | 221 | -0.46% | 1,878 | 0.12 | Village |
| Trilla | 19 | 160 | 338 | 7.38% | 829 | 0.19 | CDP |
| Allenville | 20 | 128 | 132 | -0.78% | 210 | 0.61 | Village |
| Oakland township | 21 | 127 | 130 | 0% | 3 | 36.35 | Township |
Charleston township is the largest city in Coles County, with a population of 18,828.
Oakland township is the smallest city in Coles County.
There are 21 cities in Coles County, Illinois.