| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density (/mi²) | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Oswego | 1 | 40,948 | 34,738 | 2.5% | 2,526 | 16 | Village |
| Yorkville | 2 | 27,780 | 21,766 | 3.93% | 1,359 | 20 | City |
| Montgomery | 3 | 22,365 | 20,440 | 1.76% | 2,232 | 10 | Village |
| Plano | 4 | 12,866 | 11,906 | 1.49% | 1,433 | 9 | City |
| Newark | 5 | 985 | 977 | 0.1% | 876 | 1 | Village |
| Millington | 6 | 630 | 616 | 0.16% | 890 | 1 | Village |
| Millbrook | 7 | 292 | 284 | 0.34% | 158 | 2 | Village |
Oswego is the largest city in Kendall County, with a population of 40,948.
Millbrook is the smallest city in Kendall County, with a population of 292.
There are 7 cities in Kendall County, Illinois.