25 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Dayton | 1 | 136,044 | 137,553 | -0.22% | 2,438 | 56 | City |
| Washington | 2 | 64,448 | 61,613 | 1.04% | 2,070 | 31 | Township |
| Kettering | 3 | 56,829 | 57,822 | -0.35% | 3,037 | 19 | City |
| Miami | 4 | 53,035 | 52,131 | 0.92% | 1,570 | 34 | Township |
| Centerville | 5 | 26,843 | 24,183 | 2.02% | 2,446 | 11 | City |
| Riverside | 6 | 24,471 | 24,473 | 0% | 2,516 | 10 | City |
| Miamisburg | 7 | 20,338 | 19,913 | 0.42% | 1,659 | 12 | City |
| Vandalia | 8 | 14,968 | 15,193 | -0.3% | 1,213 | 12 | City |
| Clayton | 9 | 13,293 | 13,305 | -0.02% | 718 | 19 | City |
| Englewood | 10 | 13,235 | 13,470 | -0.35% | 2,018 | 7 | City |
| West Carrollton | 11 | 12,863 | 13,100 | -0.37% | 2,001 | 6 | City |
| Clay | 12 | 8,858 | 8,880 | 0.24% | 235 | 38 | Township |
| German | 13 | 8,853 | 8,751 | 0.5% | 233 | 38 | Township |
| Moraine | 14 | 6,644 | 6,439 | 0.62% | 716 | 9 | City |
| Carlisle | 15 | 5,941 | 5,510 | 1.47% | 1,669 | 4 | Village |
| Brookville | 16 | 5,935 | 5,989 | -0.18% | 1,513 | 4 | City |
| Germantown | 17 | 5,878 | 5,803 | 0.26% | 1,392 | 4 | City |
| Fort McKinley | 18 | 5,295 | 2,925 | 7.14% | 3,966 | 1 | CDP |
| Hunter | 19 | 4,855 | 3,918 | 3.94% | 2,245 | 2 | CDP |
| New Lebanon | 20 | 3,815 | 3,805 | 0.05% | 1,866 | 2 | Village |
| Five Points | 21 | 1,609 | 1,600 | -0.86% | 781 | 2 | CDP |
| Clayton | 22 | 1,575 | 1,566 | 0.13% | 51 | 31 | Township |
| Drexel | 23 | 1,187 | 2,320 | -4.74% | 543 | 2 | CDP |
| Farmersville | 24 | 1,001 | 979 | 0.4% | 1,400 | 1 | Village |
| Phillipsburg | 25 | 497 | 500 | -0.2% | 1,868 | 0 | Village |
Dayton is the largest city in Montgomery County, with a population of 136,044.
Phillipsburg is the smallest city in Montgomery County, with a population of 497.
There are 25 cities in Montgomery County, Ohio.