33 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Oswego | 1 | 17,077 | 16,924 | 0.18% | 2,243 | 8 | City |
| Fulton | 2 | 11,201 | 11,365 | -0.29% | 2,855 | 4 | City |
| Hastings | 3 | 9,437 | 9,337 | 0.53% | 207 | 46 | Town |
| Oswego | 4 | 8,525 | 7,915 | 0.07% | 312 | 27 | Town |
| Schroeppel | 5 | 7,962 | 7,956 | 0.31% | 189 | 42 | Town |
| Scriba | 6 | 6,628 | 6,614 | 0.21% | 163 | 41 | Town |
| Granby | 7 | 6,537 | 6,520 | 0.48% | 147 | 45 | Town |
| Richland | 8 | 5,786 | 5,624 | 0.5% | 101 | 57 | Town |
| Volney | 9 | 5,657 | 5,666 | 0.21% | 117 | 48 | Town |
| Mexico | 10 | 5,364 | 5,257 | 0.79% | 116 | 46 | Town |
| Constantia | 11 | 4,818 | 4,778 | 0.56% | 85 | 57 | Town |
| Hannibal | 12 | 4,489 | 4,515 | 0.36% | 101 | 45 | Town |
| West Monroe | 13 | 4,076 | 4,088 | 0.42% | 121 | 34 | Town |
| Sandy Creek | 14 | 3,830 | 3,811 | 0.37% | 91 | 42 | Town |
| Palermo | 15 | 3,436 | 3,465 | 0.03% | 85 | 40 | Town |
| New Haven | 16 | 2,995 | 2,928 | 0.5% | 96 | 31 | Town |
| Parish | 17 | 2,409 | 2,399 | 0.54% | 58 | 42 | Town |
| Pulaski | 18 | 2,293 | 2,176 | 1.01% | 648 | 4 | Village |
| Phoenix | 19 | 2,192 | 2,220 | -0.27% | 1,872 | 1 | Village |
| Central Square | 20 | 1,845 | 1,860 | -0.16% | 968 | 2 | Village |
| Minetto | 21 | 1,625 | 1,639 | 0.18% | 282 | 6 | Town |
| Mexico | 22 | 1,552 | 1,574 | -0.32% | 724 | 2 | Village |
| Williamstown | 23 | 1,355 | 1,333 | 0.44% | 35 | 39 | Town |
| Amboy | 24 | 1,303 | 1,248 | 1.48% | 35 | 37 | Town |
| Fulton | 25 | 1,208 | 1,203 | -0.08% | 19 | 65 | Town |
| Orwell | 26 | 1,084 | 1,074 | 0.37% | 27 | 40 | Town |
| Cleveland | 27 | 728 | 737 | -0.27% | 644 | 1 | Village |
| Lacona | 28 | 673 | 673 | 0% | 605 | 1 | Village |
| Sandy Creek | 29 | 620 | 625 | -0.16% | 460 | 1 | Village |
| Hannibal | 30 | 536 | 543 | -0.37% | 465 | 1 | Village |
| Boylston | 31 | 527 | 502 | 1.35% | 13 | 39 | Town |
| Redfield | 32 | 484 | 474 | 0.41% | 5 | 90 | Town |
| Parish | 33 | 444 | 453 | -0.45% | 282 | 2 | Village |
Oswego is the largest city in Oswego County, with a population of 17,077.
Parish is the smallest city in Oswego County, with a population of 444.
There are 33 cities in Oswego County, New York.