17 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Brookville township | 1 | 5,734 | 5,692 | -0.1% | 90 | 64 | Township |
| Ray township | 2 | 4,415 | 4,325 | 0.25% | 111 | 39.61 | Township |
| Whitewater township | 3 | 2,738 | 2,713 | -0.07% | 78 | 34.98 | Township |
| Brookville | 4 | 2,657 | 2,621 | 0.26% | 1,902 | 1.40 | Town |
| Laurel township | 5 | 1,436 | 1,409 | 0.14% | 46 | 31.50 | Township |
| Springfield township | 6 | 1,178 | 1,117 | 0.86% | 33 | 35.57 | Township |
| Posey township | 7 | 1,036 | 1,017 | 0.1% | 57 | 18.09 | Township |
| Blooming Grove township | 8 | 1,026 | 1,020 | -0.19% | 48 | 21.47 | Township |
| Salt Creek township | 9 | 1,003 | 986 | 0.1% | 37 | 27.14 | Township |
| Metamora township | 10 | 937 | 922 | 0.11% | 48 | 19.43 | Township |
| Oldenburg | 11 | 650 | 644 | 0.15% | 1,512 | 0.43 | Town |
| Fairfield township | 12 | 534 | 512 | 0.56% | 40 | 13.32 | Township |
| Metamora | 13 | 459 | 410 | 4.08% | 1,133 | 0.41 | CDP |
| Laurel | 14 | 415 | 407 | 0.48% | 1,744 | 0.24 | Town |
| Bath township | 15 | 350 | 352 | -0.57% | 19 | 18.46 | Township |
| New Trenton | 16 | 260 | 233 | 0.39% | 570 | 0.46 | CDP |
| Cedar Grove | 17 | 147 | 147 | 0% | 974 | 0.15 | Town |
Brookville township is the largest city in Franklin County, with a population of 5,734.
Cedar Grove is the smallest city in Franklin County.
There are 17 cities in Franklin County, Indiana.