32 cities
| City | County | 2026 Pop. ↓ |
|---|---|---|
| Kankakee | Kankakee County | 23,299 |
| Kewanee | Henry County | 11,985 |
| Kildeer | Lake County | 4,791 |
| Knoxville | Knox County | 2,813 |
| Kenilworth | Cook County | 2,402 |
| Knollwood | Lake County | 1,944 |
| Kirkland | DeKalb County | 1,608 |
| Kincaid | Christian County | 1,296 |
| Kingston | DeKalb County | 1,090 |
| Kinmundy | Marion County | 701 |
| Kansas | Edgar County | 640 |
| Kirkwood | Warren County | 633 |
| Keithsburg | Mercer County | 545 |
| Kaneville | Kane County | 443 |
| Keyesport | Clinton County | 402 |
| Kings | DeKalb County | 396 |
| Karnak | Pulaski County | 392 |
| Kenney | De Witt County | 306 |
| Kampsville | Calhoun County | 285 |
| Kane | Greene County | 273 |
| Kingston Mines | Peoria County | 265 |
| Kilbourne | Mason County | 254 |
| Kingston | DeKalb County | 242 |
| Kappa | McLean County | 232 |
| Kangley | LaSalle County | 227 |
| Kinderhook | Pike County | 181 |
| Kempton | Ford County | 177 |
| Keensburg | Wabash County | 169 |
| Kell | Marion County | 168 |
| Kinsman | Grundy County | 86 |
| Keenes | Wayne County | 49 |
| Kaskaskia | Randolph County | 23 |