12 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Warrenton | 1 | 9,635 | 8,439 | 2.28% | 1,065 | 9 | City |
| Warrenton | 2 | 9,635 | 8,559 | 2.28% | 1,065 | 9 | City |
| Wright City | 3 | 5,941 | 4,806 | 3.81% | 980 | 6 | City |
| Wright City | 4 | 5,941 | 4,850 | 3.81% | 980 | 6 | City |
| Marthasville | 5 | 1,312 | 1,259 | 0.77% | 1,536 | 1 | City |
| Marthasville | 6 | 1,312 | 1,260 | 0.77% | 1,536 | 1 | City |
| Truesdale | 7 | 943 | 861 | 1.51% | 736 | 1 | City |
| Truesdale | 8 | 943 | 870 | 1.51% | 736 | 1 | City |
| Pendleton | 9 | 36 | 34 | 0% | 118 | 0 | Village |
| Pendleton | 10 | 36 | 34 | 0% | 118 | 0 | Village |
| Three Creeks | 11 | 8 | 8 | 0% | 2 | 5 | Village |
| Three Creeks | 12 | 8 | 8 | 0% | 2 | 5 | Village |
Warrenton is the largest city in Warren County, with a population of 9,635.
Three Creeks is the smallest city in Warren County, with a population of 8.
There are 12 cities in Warren County, Missouri.