10 cities
| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Mason | 1 | 36,626 | 34,886 | 0.8% | 1,880 | 19 | City |
| Lebanon | 2 | 22,553 | 20,879 | 1.25% | 1,674 | 13 | City |
| Springboro | 3 | 19,900 | 19,137 | 0.64% | 2,161 | 9 | City |
| Franklin | 4 | 11,793 | 11,688 | 0.15% | 1,253 | 9 | City |
| South Lebanon | 5 | 7,152 | 6,464 | 1.63% | 2,086 | 3 | Village |
| Waynesville | 6 | 2,953 | 2,679 | 1.58% | 1,250 | 2 | Village |
| Morrow | 7 | 2,267 | 2,063 | 1.52% | 1,113 | 2 | Village |
| Maineville | 8 | 1,567 | 1,416 | 1.62% | 987 | 2 | Village |
| Harveysburg | 9 | 591 | 555 | 1.03% | 595 | 1 | Village |
| Pleasant Plain | 10 | 144 | 129 | 2.13% | 889 | 0 | Village |
Mason is the largest city in Warren County, with a population of 36,626.
Pleasant Plain is the smallest city in Warren County, with a population of 144.
There are 10 cities in Warren County, Ohio.