| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density (/mi²) | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Morris | 1 | 14,748 | 14,230 | 0.54% | 1,163 | 13 | City |
| Minooka | 2 | 12,931 | 12,742 | 0.25% | 1,421 | 9 | Village |
| Coal City | 3 | 5,856 | 5,695 | 0.43% | 1,015 | 6 | Village |
| Diamond | 4 | 2,729 | 2,632 | 0.55% | 1,436 | 2 | Village |
| Gardner | 5 | 1,367 | 1,359 | 0.07% | 469 | 3 | Village |
| Mazon | 6 | 984 | 981 | 0% | 1,635 | 1 | Village |
| Braceville | 7 | 732 | 722 | 0% | 235 | 3 | Village |
| South Wilmington | 8 | 721 | 707 | 0.28% | 1,465 | 0 | Village |
| Godley | 9 | 651 | 573 | 2.2% | 601 | 1 | Village |
| Carbon Hill | 10 | 382 | 376 | 0.26% | 2,099 | 0 | Village |
| Lisbon | 11 | 268 | 263 | 0.37% | 127 | 2 | Village |
| Plattville | 12 | 220 | 217 | 0% | 97 | 2 | Village |
| Verona | 13 | 206 | 208 | -0.48% | 1,248 | 0 | Village |
| Symerton | 14 | 123 | 126 | -0.81% | 783 | 0 | Village |
| Kinsman | 15 | 91 | 91 | 0% | 1,338 | 0 | Village |
| East Brooklyn | 16 | 75 | 73 | 0% | 1,442 | 0 | Village |
Morris is the largest city in Grundy County, with a population of 14,748.
East Brooklyn is the smallest city in Grundy County, with a population of 75.
There are 16 cities in Grundy County, Illinois.