21 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Charleston | 1 | 19,312 | 19,621 | -0.29% | 520 | 37 | Township |
| Charleston | 2 | 17,306 | 17,579 | -0.32% | 1,947 | 9 | City |
| Mattoon | 3 | 16,539 | 16,853 | -0.38% | 1,604 | 10 | City |
| Mattoon | 4 | 14,373 | 14,610 | -0.13% | 398 | 36 | Township |
| Lafayette | 5 | 4,643 | 4,715 | -0.17% | 128 | 36 | Township |
| East Oakland | 6 | 1,205 | 1,227 | -0.33% | 31 | 39 | Township |
| Humboldt | 7 | 1,188 | 1,210 | -0.25% | 22 | 53 | Township |
| Pleasant Grove | 8 | 1,185 | 1,206 | -0.17% | 28 | 42 | Township |
| Ashmore | 9 | 1,117 | 1,141 | -0.36% | 21 | 54 | Township |
| North Okaw | 10 | 973 | 1,000 | -0.61% | 18 | 54 | Township |
| Paradise | 11 | 961 | 973 | -0.21% | 41 | 23 | Township |
| Hutton | 12 | 761 | 774 | -0.26% | 14 | 55 | Township |
| Oakland | 13 | 716 | 734 | -0.56% | 914 | 1 | City |
| Ashmore | 14 | 624 | 637 | -0.48% | 775 | 1 | Village |
| Humboldt | 15 | 355 | 360 | -0.28% | 1,035 | 0 | Village |
| Seven Hickory | 16 | 305 | 310 | -0.33% | 6 | 52 | Township |
| Morgan | 17 | 291 | 297 | -0.34% | 11 | 26 | Township |
| Lerna | 18 | 217 | 221 | -0.46% | 1,887 | 0 | Village |
| Trilla | 19 | 160 | 338 | 7.38% | 829 | 0 | CDP |
| Allenville | 20 | 129 | 132 | -0.77% | 212 | 1 | Village |
| Oakland | 21 | 128 | 130 | 0% | 4 | 36 | Township |
Charleston is the largest city in Coles County, with a population of 19,312.
Oakland is the smallest city in Coles County, with a population of 128.
There are 21 cities in Coles County, Illinois.