14 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Seneca Falls | 1 | 8,928 | 9,074 | 0.11% | 369 | 24 | Town |
| Waterloo | 2 | 7,301 | 7,365 | 0.15% | 337 | 22 | Town |
| Waterloo | 3 | 4,689 | 4,851 | -0.7% | 2,174 | 2 | Village |
| Fayette | 4 | 3,591 | 3,650 | 0.2% | 66 | 55 | Town |
| Romulus | 5 | 3,199 | 3,424 | 6% | 85 | 38 | Town |
| Ovid | 6 | 2,290 | 2,311 | 0.35% | 74 | 31 | Town |
| Covert | 7 | 2,105 | 2,151 | 0.24% | 67 | 31 | Town |
| Varick | 8 | 1,631 | 1,657 | 0.25% | 51 | 32 | Town |
| Lodi | 9 | 1,474 | 1,483 | 0.14% | 43 | 34 | Town |
| Junius | 10 | 1,370 | 1,387 | 0.22% | 51 | 27 | Town |
| Tyre | 11 | 995 | 1,010 | 0.3% | 33 | 30 | Town |
| Interlaken | 12 | 613 | 628 | -0.49% | 1,997 | 0 | Village |
| Ovid | 13 | 531 | 551 | -0.75% | 1,334 | 0 | Village |
| Lodi | 14 | 278 | 287 | -0.71% | 505 | 1 | Village |
Seneca Falls is the largest city in Seneca County, with a population of 8,928.
Lodi is the smallest city in Seneca County, with a population of 278.
There are 14 cities in Seneca County, New York.