13 cities
| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Rochelle | 1 | 9,529 | 9,472 | 0.11% | 693 | 14 | City |
| Byron | 2 | 3,753 | 3,785 | -0.13% | 807 | 5 | City |
| Oregon | 3 | 3,540 | 3,630 | -0.42% | 1,837 | 2 | City |
| Mount Morris | 4 | 2,764 | 2,847 | -0.5% | 1,772 | 2 | Village |
| Davis Junction | 5 | 2,545 | 2,511 | 0.24% | 606 | 4 | Village |
| Polo | 6 | 2,216 | 2,282 | -0.49% | 1,527 | 1 | City |
| Forreston | 7 | 1,387 | 1,434 | -0.57% | 1,471 | 1 | Village |
| Stillman Valley | 8 | 1,042 | 1,071 | -0.48% | 1,828 | 1 | Village |
| New Milford | 9 | 809 | 802 | 0.12% | 287 | 3 | Village |
| Creston | 10 | 614 | 626 | -0.32% | 536 | 1 | Village |
| Leaf River | 11 | 414 | 428 | -0.48% | 476 | 1 | Village |
| Monroe Center | 12 | 402 | 413 | -0.5% | 332 | 1 | Village |
| Adeline | 13 | 74 | 76 | 0% | 278 | 0 | Village |
Rochelle is the largest city in Ogle County, with a population of 9,529.
Adeline is the smallest city in Ogle County, with a population of 74.
There are 13 cities in Ogle County, Illinois.