12 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Sedalia | 1 | 22,452 | 21,731 | 0.64% | 1,571 | 14 | City |
| Sedalia | 2 | 22,452 | 21,742 | 0.64% | 1,571 | 14 | City |
| La Monte | 3 | 1,010 | 1,004 | 0.1% | 931 | 1 | City |
| La Monte | 4 | 1,010 | 1,005 | 0.1% | 931 | 1 | City |
| Green Ridge | 5 | 631 | 470 | 5.34% | 1,471 | 0 | City |
| Green Ridge | 6 | 631 | 470 | 5.34% | 1,471 | 0 | City |
| Smithton | 7 | 503 | 506 | -0.2% | 1,671 | 0 | City |
| Smithton | 8 | 503 | 506 | -0.2% | 1,671 | 0 | City |
| Houstonia | 9 | 195 | 194 | 0% | 985 | 0 | City |
| Houstonia | 10 | 195 | 194 | 0% | 985 | 0 | City |
| Hughesville | 11 | 152 | 149 | 0% | 1,310 | 0 | Village |
| Hughesville | 12 | 152 | 149 | 0% | 1,310 | 0 | Village |
Sedalia is the largest city in Pettis County, with a population of 22,452.
Hughesville is the smallest city in Pettis County, with a population of 152.
There are 12 cities in Pettis County, Missouri.