12 cities
| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Trenton | 1 | 5,926 | 5,973 | -0.45% | 124 | 48 | Township |
| Trenton | 2 | 5,591 | 5,582 | 0.04% | 867 | 6 | City |
| Jefferson | 3 | 469 | 472 | -0.42% | 13 | 36 | Township |
| Wilson | 4 | 344 | 347 | -0.29% | 10 | 34 | Township |
| Marion | 5 | 257 | 259 | -0.39% | 6 | 42 | Township |
| Spickard | 6 | 219 | 221 | 0% | 347 | 1 | City |
| Galt | 7 | 166 | 166 | 0% | 580 | 0 | City |
| Myers | 8 | 159 | 158 | 0% | 5 | 35 | Township |
| Laredo | 9 | 154 | 156 | 0% | 560 | 0 | City |
| Harrison | 10 | 102 | 101 | 0% | 5 | 22 | Township |
| Tindall | 11 | 49 | 49 | 0% | 371 | 0 | Town |
| Osgood | 12 | 21 | 23 | 0% | 115 | 0 | Village |
Trenton is the largest city in Grundy County, with a population of 5,926.
Osgood is the smallest city in Grundy County, with a population of 21.
There are 12 cities in Grundy County, Missouri.