9 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Grundy Center | 1 | 2,823 | 2,810 | 0.07% | 1,098 | 3 | City |
| Reinbeck | 2 | 1,673 | 1,671 | 0% | 771 | 2 | City |
| Dike | 3 | 1,291 | 1,299 | -0.15% | 929 | 1 | City |
| Conrad | 4 | 1,099 | 1,094 | 0.09% | 894 | 1 | City |
| Wellsburg | 5 | 706 | 718 | -0.42% | 643 | 1 | City |
| Holland | 6 | 260 | 264 | -0.38% | 1,032 | 0 | City |
| Stout | 7 | 194 | 193 | 0% | 664 | 0 | City |
| Beaman | 8 | 154 | 158 | -0.65% | 824 | 0 | City |
| Morrison | 9 | 101 | 99 | 0% | 1,063 | 0 | City |
Grundy Center is the largest city in Grundy County, with a population of 2,823.
Morrison is the smallest city in Grundy County, with a population of 101.
There are 9 cities in Grundy County, Iowa.