12 cities
| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Shelbyville | 1 | 4,485 | 4,650 | -0.6% | 1,098 | 4 | City |
| Lakewood | 2 | 4,295 | 4,270 | 0.09% | 936 | 5 | Village |
| Windsor | 3 | 1,021 | 1,069 | -0.78% | 1,621 | 1 | City |
| Stewardson | 4 | 717 | 719 | 0% | 1,170 | 1 | Village |
| Windsor | 5 | 643 | 669 | -0.62% | 1,468 | 0 | Village |
| Findlay | 6 | 640 | 666 | -0.62% | 693 | 1 | Village |
| Strasburg | 7 | 509 | 533 | -0.78% | 941 | 1 | Village |
| Cowden | 8 | 491 | 514 | -0.81% | 1,221 | 0 | Village |
| Tower Hill | 9 | 469 | 481 | -0.42% | 467 | 1 | Village |
| Herrick | 10 | 356 | 362 | -0.28% | 973 | 0 | Village |
| Sigel | 11 | 314 | 323 | -0.32% | 1,117 | 0 | Town |
| Oconee | 12 | 134 | 139 | -0.74% | 376 | 0 | Village |
Shelbyville is the largest city in Shelby County, with a population of 4,485.
Oconee is the smallest city in Shelby County, with a population of 134.
There are 12 cities in Shelby County, Illinois.