27 cities
| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Freeport | 1 | 22,850 | 23,960 | -0.63% | 1,926 | 12 | Township |
| Freeport | 2 | 22,730 | 23,960 | -0.89% | 1,915 | 12 | City |
| Lena | 3 | 2,619 | 2,759 | -0.87% | 988 | 3 | Village |
| Rock Run | 4 | 2,093 | 2,184 | -0.52% | 44 | 48 | Township |
| Harlem | 5 | 1,924 | 2,005 | -0.57% | 61 | 32 | Township |
| Rock Grove | 6 | 1,441 | 1,495 | -0.41% | 48 | 30 | Township |
| Ridott | 7 | 1,288 | 1,345 | -0.54% | 24 | 54 | Township |
| Loran | 8 | 1,286 | 1,348 | -0.69% | 37 | 35 | Township |
| Oneco | 9 | 1,227 | 1,284 | -0.57% | 45 | 27 | Township |
| Buckeye | 10 | 1,141 | 1,198 | -0.7% | 32 | 36 | Township |
| Florence | 11 | 1,114 | 1,168 | -0.71% | 33 | 34 | Township |
| Dakota | 12 | 774 | 811 | -0.51% | 43 | 18 | Township |
| Pearl City | 13 | 744 | 780 | -0.8% | 1,152 | 1 | Village |
| Orangeville | 14 | 725 | 766 | -0.96% | 1,069 | 1 | Village |
| Waddams | 15 | 699 | 733 | -0.71% | 20 | 36 | Township |
| Cedarville | 16 | 632 | 670 | -0.94% | 1,371 | 0 | Village |
| Kent | 17 | 612 | 636 | -0.33% | 17 | 36 | Township |
| Silver Creek | 18 | 596 | 623 | -0.67% | 17 | 35 | Township |
| Davis | 19 | 557 | 590 | -0.89% | 1,362 | 0 | Village |
| Winslow | 20 | 539 | 567 | -0.74% | 19 | 29 | Township |
| Dakota | 21 | 469 | 499 | -1.05% | 1,884 | 0 | Village |
| German Valley | 22 | 409 | 432 | -0.97% | 880 | 0 | Village |
| Erin | 23 | 366 | 382 | -0.54% | 20 | 18 | Township |
| Rock City | 24 | 282 | 296 | -0.7% | 2,074 | 0 | Village |
| Winslow | 25 | 264 | 282 | -1.12% | 576 | 0 | Village |
| Jefferson | 26 | 239 | 248 | -0.42% | 13 | 18 | Township |
| Ridott | 27 | 121 | 127 | -0.82% | 1,513 | 0 | Village |
Freeport is the largest city in Stephenson County, with a population of 22,850.
Ridott is the smallest city in Stephenson County, with a population of 121.
There are 27 cities in Stephenson County, Illinois.