29 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Freeport | 1 | 22,656 | 23,896 | -1.05% | 1,909 | 12 | Township |
| Freeport | 2 | 22,629 | 23,896 | -1.11% | 1,907 | 12 | City |
| Lena | 3 | 2,604 | 2,756 | -1.14% | 982 | 3 | Village |
| Lake Summerset | 4 | 2,132 | 1,958 | 0.28% | 1,006 | 2 | CDP |
| Rock Run | 5 | 2,075 | 2,182 | -0.95% | 43 | 48 | Township |
| Harlem | 6 | 1,910 | 2,005 | -0.98% | 61 | 32 | Township |
| Rock Grove | 7 | 1,420 | 1,493 | -1.05% | 47 | 30 | Township |
| Loran | 8 | 1,283 | 1,350 | -1.08% | 37 | 35 | Township |
| Ridott | 9 | 1,272 | 1,347 | -1.17% | 24 | 54 | Township |
| Oneco | 10 | 1,214 | 1,283 | -1.14% | 44 | 27 | Township |
| Buckeye | 11 | 1,130 | 1,198 | -1.22% | 31 | 36 | Township |
| Florence | 12 | 1,112 | 1,169 | -0.98% | 33 | 34 | Township |
| Willow Lake | 13 | 1,042 | 752 | 7.09% | 381 | 3 | CDP |
| Dakota | 14 | 773 | 813 | -0.9% | 43 | 18 | Township |
| Pearl City | 15 | 744 | 783 | -1.06% | 1,152 | 1 | Village |
| Orangeville | 16 | 725 | 767 | -1.09% | 1,069 | 1 | Village |
| Waddams | 17 | 688 | 730 | -1.29% | 19 | 36 | Township |
| Cedarville | 18 | 630 | 669 | -1.25% | 1,367 | 0 | Village |
| Kent | 19 | 601 | 635 | -1.15% | 17 | 36 | Township |
| Silver Creek | 20 | 595 | 623 | -1% | 17 | 35 | Township |
| Davis | 21 | 558 | 590 | -1.06% | 1,364 | 0 | Village |
| Winslow | 22 | 539 | 569 | -1.1% | 19 | 29 | Township |
| Dakota | 23 | 470 | 499 | -1.26% | 1,888 | 0 | Village |
| German Valley | 24 | 407 | 432 | -1.21% | 875 | 0 | Village |
| Erin | 25 | 363 | 380 | -0.82% | 20 | 18 | Township |
| Rock City | 26 | 276 | 295 | -1.43% | 2,029 | 0 | Village |
| Winslow | 27 | 266 | 283 | -1.12% | 581 | 0 | Village |
| Jefferson | 28 | 237 | 248 | -0.84% | 13 | 18 | Township |
| Ridott | 29 | 120 | 127 | -0.83% | 1,500 | 0 | Village |
Freeport is the largest city in Stephenson County, with a population of 22,656.
Ridott is the smallest city in Stephenson County, with a population of 120.
There are 29 cities in Stephenson County, Illinois.