16 cities
| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Dayton | 1 | 135,742 | 137,553 | -0.22% | 2,432 | 56 | City |
| Kettering | 2 | 56,631 | 57,822 | -0.35% | 3,026 | 19 | City |
| Centerville | 3 | 27,375 | 24,183 | 1.98% | 2,494 | 11 | City |
| Riverside | 4 | 24,471 | 24,473 | 0% | 2,516 | 10 | City |
| Miamisburg | 5 | 20,423 | 19,913 | 0.42% | 1,666 | 12 | City |
| Vandalia | 6 | 14,923 | 15,193 | -0.3% | 1,209 | 12 | City |
| Clayton | 7 | 13,291 | 13,305 | -0.02% | 718 | 19 | City |
| Englewood | 8 | 13,188 | 13,470 | -0.36% | 2,010 | 7 | City |
| West Carrollton | 9 | 12,816 | 13,100 | -0.37% | 1,994 | 6 | City |
| Moraine | 10 | 6,685 | 6,439 | 0.62% | 720 | 9 | City |
| Carlisle | 11 | 6,027 | 5,510 | 1.45% | 1,693 | 4 | Village |
| Brookville | 12 | 5,924 | 5,989 | -0.19% | 1,446 | 4 | City |
| Germantown | 13 | 5,893 | 5,803 | 0.26% | 1,396 | 4 | City |
| New Lebanon | 14 | 3,817 | 3,805 | 0.05% | 1,867 | 2 | Village |
| Farmersville | 15 | 1,006 | 979 | 0.5% | 1,407 | 1 | Village |
| Phillipsburg | 16 | 497 | 500 | 0% | 1,868 | 0 | Village |
Dayton is the largest city in Montgomery County, with a population of 135,742.
Phillipsburg is the smallest city in Montgomery County, with a population of 497.
There are 16 cities in Montgomery County, Ohio.