16 cities
| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Morris | 1 | 14,764 | 14,233 | 0.61% | 1,164 | 13 | City |
| Minooka | 2 | 12,983 | 12,755 | 0.29% | 1,427 | 9 | Village |
| Coal City | 3 | 5,864 | 5,701 | 0.46% | 1,017 | 6 | Village |
| Diamond | 4 | 2,737 | 2,632 | 0.66% | 1,441 | 2 | Village |
| Gardner | 5 | 1,369 | 1,359 | 0.15% | 470 | 3 | Village |
| Mazon | 6 | 984 | 978 | 0.1% | 1,635 | 1 | Village |
| Braceville | 7 | 722 | 721 | 0% | 232 | 3 | Village |
| South Wilmington | 8 | 720 | 704 | 0.42% | 1,463 | 0 | Village |
| Godley | 9 | 664 | 573 | 2.31% | 613 | 1 | Village |
| Carbon Hill | 10 | 387 | 375 | 0.52% | 2,126 | 0 | Village |
| Lisbon | 11 | 276 | 270 | 0.36% | 130 | 2 | Village |
| Plattville | 12 | 222 | 218 | 0.45% | 98 | 2 | Village |
| Verona | 13 | 208 | 205 | 0.48% | 1,261 | 0 | Village |
| Symerton | 14 | 123 | 125 | 0% | 783 | 0 | Village |
| Kinsman | 15 | 86 | 89 | 0% | 1,265 | 0 | Village |
| East Brooklyn | 16 | 80 | 77 | 1.27% | 1,538 | 0 | Village |
Morris is the largest city in Grundy County, with a population of 14,764.
East Brooklyn is the smallest city in Grundy County, with a population of 80.
There are 16 cities in Grundy County, Illinois.