35 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 |
| Shelbyville | 2 | 4,335 | 4,483 | -0.53% | 127 | 34 | Township |
| Lakewood | 3 | 4,295 | 4,270 | 0.09% | 936 | 5 | Village |
| Rose | 4 | 1,866 | 1,912 | -0.27% | 53 | 35 | Township |
| Windsor | 5 | 1,330 | 1,378 | -0.45% | 46 | 29 | Township |
| Prairie | 6 | 1,196 | 1,207 | -0.17% | 22 | 54 | Township |
| Windsor | 7 | 1,021 | 1,069 | -0.78% | 1,621 | 1 | City |
| Tower Hill | 8 | 951 | 966 | -0.11% | 27 | 35 | Township |
| Dry Point | 9 | 937 | 956 | -0.11% | 39 | 24 | Township |
| Okaw | 10 | 878 | 890 | 0.11% | 28 | 31 | Township |
| Richland | 11 | 783 | 809 | -0.38% | 22 | 36 | Township |
| Oconee | 12 | 774 | 784 | 0.13% | 14 | 55 | Township |
| Stewardson | 13 | 717 | 719 | 0% | 1,170 | 1 | Village |
| Sigel | 14 | 710 | 721 | 0% | 30 | 24 | Township |
| Windsor | 15 | 643 | 669 | -0.62% | 1,468 | 0 | Village |
| Findlay | 16 | 640 | 666 | -0.62% | 693 | 1 | Village |
| Big Spring | 17 | 608 | 614 | 0.16% | 21 | 29 | Township |
| Herrick | 18 | 539 | 543 | 0.19% | 31 | 17 | Township |
| Strasburg | 19 | 509 | 533 | -0.78% | 941 | 1 | Village |
| Cowden | 20 | 491 | 514 | -0.81% | 1,221 | 0 | Village |
| Tower Hill | 21 | 469 | 481 | -0.42% | 467 | 1 | Village |
| Todds Point | 22 | 454 | 466 | -0.22% | 24 | 19 | Township |
| Flat Branch | 23 | 415 | 419 | 0.24% | 12 | 34 | Township |
| Ash Grove | 24 | 409 | 413 | 0% | 10 | 42 | Township |
| Ridge | 25 | 402 | 412 | -0.5% | 11 | 35 | Township |
| Holland | 26 | 385 | 392 | -0.26% | 14 | 27 | Township |
| Lakewood | 27 | 384 | 391 | -0.26% | 13 | 30 | Township |
| Clarksburg | 28 | 356 | 361 | -0.28% | 13 | 27 | Township |
| Herrick | 29 | 356 | 362 | -0.28% | 973 | 0 | Village |
| Cold Spring | 30 | 317 | 322 | 0% | 9 | 35 | Township |
| Sigel | 31 | 314 | 323 | -0.32% | 1,117 | 0 | Town |
| Rural | 32 | 306 | 312 | -0.65% | 9 | 35 | Township |
| Pickaway | 33 | 148 | 152 | -0.67% | 5 | 30 | Township |
| Oconee | 34 | 134 | 139 | -0.74% | 376 | 0 | Village |
| Penn | 35 | 81 | 86 | -1.22% | 3 | 24 | Township |
Shelbyville is the largest city in Shelby County, with a population of 4,485.
Penn is the smallest city in Shelby County, with a population of 81.
There are 35 cities in Shelby County, Illinois.