39 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Clear Creek | 1 | 38,525 | 36,417 | 0.78% | 842 | 46 | Township |
| Mason | 2 | 36,336 | 34,886 | 0.8% | 1,865 | 19 | City |
| Franklin | 3 | 33,295 | 31,677 | 0.87% | 1,012 | 33 | Township |
| Lebanon | 4 | 22,274 | 20,879 | 1.27% | 1,653 | 13 | City |
| Springboro | 5 | 19,773 | 19,137 | 0.65% | 2,147 | 9 | City |
| Turtlecreek | 6 | 18,205 | 17,746 | 1.05% | 301 | 60 | Township |
| Franklin | 7 | 11,775 | 11,688 | 0.14% | 1,251 | 9 | City |
| Franklin | 8 | 11,193 | 11,432 | 0.16% | 1,641 | 7 | Township |
| South Lebanon | 9 | 7,037 | 6,464 | 1.65% | 2,052 | 3 | Village |
| Union | 10 | 6,806 | 6,286 | 1.23% | 511 | 13 | Township |
| Franklin | 11 | 6,409 | 6,289 | 0.47% | 513 | 13 | Township |
| Harlan | 12 | 5,346 | 4,951 | 1.15% | 118 | 45 | Township |
| Franklin | 13 | 4,739 | 4,824 | -0.59% | 206 | 23 | Township |
| Franklin | 14 | 4,241 | 4,236 | 0.09% | 118 | 36 | Township |
| Franklin | 15 | 3,747 | 3,607 | 0.97% | 95 | 39 | Township |
| Franklin | 16 | 3,498 | 3,491 | 0.37% | 141 | 25 | Township |
| Washington | 17 | 2,999 | 2,770 | 1.25% | 88 | 34 | Township |
| Waynesville | 18 | 2,907 | 2,679 | 1.57% | 1,230 | 2 | Village |
| Franklin | 19 | 2,612 | 2,508 | 0.85% | 105 | 25 | Township |
| Franklin | 20 | 2,306 | 2,302 | 0.22% | 63 | 37 | Township |
| Morrow | 21 | 2,233 | 2,063 | 1.55% | 1,096 | 2 | Village |
| Franklin | 22 | 2,211 | 2,130 | 0.55% | 90 | 25 | Township |
| Franklin | 23 | 1,743 | 1,702 | 1.1% | 65 | 27 | Township |
| Franklin | 24 | 1,697 | 1,710 | -0.18% | 81 | 21 | Township |
| Franklin | 25 | 1,649 | 1,616 | 0.55% | 60 | 27 | Township |
| Maineville | 26 | 1,542 | 1,416 | 1.65% | 971 | 2 | Village |
| Franklin | 27 | 1,427 | 1,448 | -0.42% | 41 | 35 | Township |
| Massie | 28 | 1,274 | 1,190 | 1.27% | 69 | 18 | Township |
| Franklin | 29 | 1,184 | 1,151 | 0.68% | 49 | 24 | Township |
| Franklin | 30 | 1,174 | 1,186 | 0% | 47 | 25 | Township |
| Franklin | 31 | 1,042 | 1,037 | 0.29% | 19 | 54 | Township |
| Mason | 32 | 945 | 986 | -0.63% | 24 | 39 | Township |
| Lebanon | 33 | 872 | 902 | -1.13% | 24 | 36 | Township |
| Franklin | 34 | 740 | 759 | -0.27% | 32 | 23 | Township |
| Franklin | 35 | 673 | 686 | 0% | 23 | 29 | Township |
| Harveysburg | 36 | 585 | 555 | 1.04% | 589 | 1 | Village |
| Franklin | 37 | 518 | 540 | -0.96% | 25 | 20 | Township |
| Franklin | 38 | 357 | 370 | -1.11% | 15 | 24 | Township |
| Pleasant Plain | 39 | 141 | 129 | 1.44% | 870 | 0 | Village |
Clear Creek is the largest city in Warren County, with a population of 38,525.
Pleasant Plain is the smallest city in Warren County, with a population of 141.
There are 39 cities in Warren County, Ohio.