17 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Brookville | 1 | 5,750 | 5,695 | -0.21% | 90 | 64 | Township |
| Ray | 2 | 4,388 | 4,322 | -0.2% | 111 | 40 | Township |
| Whitewater | 3 | 2,734 | 2,712 | -0.26% | 78 | 35 | Township |
| Brookville | 4 | 2,663 | 2,623 | 0.3% | 1,906 | 1 | Town |
| Laurel | 5 | 1,424 | 1,409 | -0.28% | 45 | 32 | Township |
| Springfield | 6 | 1,180 | 1,118 | 0.77% | 33 | 36 | Township |
| Blooming Grove | 7 | 1,029 | 1,021 | -0.39% | 48 | 21 | Township |
| Posey | 8 | 1,029 | 1,015 | -0.1% | 57 | 18 | Township |
| Salt Creek | 9 | 998 | 986 | -0.3% | 37 | 27 | Township |
| Metamora | 10 | 936 | 921 | -0.11% | 48 | 19 | Township |
| Oldenburg | 11 | 648 | 642 | 0.15% | 1,507 | 0 | Town |
| Fairfield | 12 | 533 | 511 | 0.38% | 40 | 13 | Township |
| Metamora | 13 | 459 | 410 | 4.08% | 1,133 | 0 | CDP |
| Laurel | 14 | 412 | 409 | 0% | 1,731 | 0 | Town |
| Bath | 15 | 355 | 353 | 0% | 19 | 18 | Township |
| New Trenton | 16 | 260 | 233 | 0.39% | 570 | 0 | CDP |
| Cedar Grove | 17 | 146 | 146 | 0% | 967 | 0 | Town |
Brookville is the largest city in Franklin County, with a population of 5,750.
Cedar Grove is the smallest city in Franklin County, with a population of 146.
There are 17 cities in Franklin County, Indiana.