14 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Trenton | 1 | 5,982 | 5,972 | -0.27% | 126 | 48 | Township |
| Trenton | 2 | 5,648 | 5,583 | 0.23% | 876 | 6 | City |
| Jefferson | 3 | 462 | 470 | -0.86% | 13 | 36 | Township |
| Wilson | 4 | 345 | 347 | -0.29% | 10 | 34 | Township |
| Marion | 5 | 260 | 258 | 0% | 6 | 42 | Township |
| Spickard | 6 | 226 | 223 | 0.44% | 358 | 1 | City |
| Leisure Lake | 7 | 209 | 130 | 1.46% | 150 | 1 | CDP |
| Galt | 8 | 166 | 166 | 0% | 580 | 0 | City |
| Myers | 9 | 160 | 158 | 0% | 5 | 35 | Township |
| Laredo | 10 | 156 | 155 | 0% | 567 | 0 | City |
| Edinburg | 11 | 109 | 84 | 6.86% | 102 | 1 | CDP |
| Harrison | 12 | 100 | 101 | -0.99% | 5 | 22 | Township |
| Tindall | 13 | 47 | 47 | 0% | 356 | 0 | Town |
| Osgood | 14 | 23 | 25 | 0% | 126 | 0 | Village |
Trenton is the largest city in Grundy County, with a population of 5,982.
Osgood is the smallest city in Grundy County, with a population of 23.
There are 14 cities in Grundy County, Missouri.