29 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Freeport | 1 | 22,995 | 23,960 | -0.63% | 1,938 | 12 | Township |
| Freeport | 2 | 22,935 | 23,960 | -0.89% | 1,933 | 12 | City |
| Lena | 3 | 2,642 | 2,759 | -0.9% | 997 | 3 | Village |
| Lake Summerset | 4 | 2,132 | 1,958 | 0.28% | 1,006 | 2 | CDP |
| Rock Run | 5 | 2,104 | 2,184 | -0.52% | 44 | 48 | Township |
| Harlem | 6 | 1,935 | 2,005 | -0.57% | 61 | 32 | Township |
| Rock Grove | 7 | 1,447 | 1,495 | -0.41% | 48 | 30 | Township |
| Loran | 8 | 1,295 | 1,348 | -0.69% | 37 | 35 | Township |
| Ridott | 9 | 1,295 | 1,345 | -0.54% | 24 | 54 | Township |
| Oneco | 10 | 1,234 | 1,284 | -0.56% | 45 | 27 | Township |
| Buckeye | 11 | 1,149 | 1,198 | -0.69% | 32 | 36 | Township |
| Florence | 12 | 1,122 | 1,168 | -0.71% | 33 | 34 | Township |
| Willow Lake | 13 | 1,042 | 752 | 7.09% | 381 | 3 | CDP |
| Dakota | 14 | 778 | 811 | -0.51% | 43 | 18 | Township |
| Pearl City | 15 | 750 | 780 | -0.79% | 1,161 | 1 | Village |
| Orangeville | 16 | 732 | 766 | -0.95% | 1,080 | 1 | Village |
| Waddams | 17 | 704 | 733 | -0.71% | 20 | 36 | Township |
| Cedarville | 18 | 638 | 670 | -1.09% | 1,384 | 0 | Village |
| Kent | 19 | 614 | 636 | -0.32% | 17 | 36 | Township |
| Silver Creek | 20 | 600 | 623 | -0.66% | 17 | 35 | Township |
| Davis | 21 | 562 | 590 | -1.06% | 1,374 | 0 | Village |
| Winslow | 22 | 543 | 567 | -0.73% | 19 | 29 | Township |
| Dakota | 23 | 474 | 499 | -1.04% | 1,904 | 0 | Village |
| German Valley | 24 | 413 | 432 | -0.96% | 888 | 0 | Village |
| Erin | 25 | 368 | 382 | -0.54% | 20 | 18 | Township |
| Rock City | 26 | 284 | 296 | -1.05% | 2,088 | 0 | Village |
| Winslow | 27 | 267 | 282 | -1.11% | 583 | 0 | Village |
| Jefferson | 28 | 240 | 248 | -0.41% | 13 | 18 | Township |
| Ridott | 29 | 122 | 127 | -0.81% | 1,525 | 0 | Village |
Freeport is the largest city in Stephenson County, with a population of 22,995.
Ridott is the smallest city in Stephenson County, with a population of 122.
There are 29 cities in Stephenson County, Illinois.