31 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Oswego | 1 | 17,093 | 16,915 | 0.21% | 2,245 | 7.61 | City |
| Fulton | 2 | 11,166 | 11,371 | -0.37% | 2,846 | 3.92 | City |
| Hastings | 3 | 9,362 | 9,337 | 0.07% | 205 | 45.65 | Town |
| Oswego | 4 | 8,593 | 7,918 | -0.15% | 314 | 27.33 | Town |
| Schroeppel | 5 | 7,910 | 7,960 | -0.15% | 187 | 42.20 | Town |
| Scriba | 6 | 6,674 | 6,612 | 0.5% | 165 | 40.57 | Town |
| Granby | 7 | 6,477 | 6,520 | -0.09% | 145 | 44.55 | Town |
| Richland | 8 | 5,735 | 5,619 | 0.09% | 100 | 57.25 | Town |
| Volney | 9 | 5,645 | 5,659 | 0.02% | 117 | 48.24 | Town |
| Mexico | 10 | 5,327 | 5,260 | 0.32% | 115 | 46.27 | Town |
| Constantia | 11 | 4,762 | 4,777 | -0.02% | 84 | 56.77 | Town |
| Hannibal | 12 | 4,434 | 4,516 | -0.34% | 99 | 44.66 | Town |
| West Monroe | 13 | 4,022 | 4,086 | -0.35% | 119 | 33.75 | Town |
| Sandy Creek | 14 | 3,808 | 3,811 | -0.03% | 90 | 42.28 | Town |
| Palermo | 15 | 3,433 | 3,465 | -0.2% | 85 | 40.46 | Town |
| New Haven | 16 | 2,986 | 2,926 | 0.24% | 96 | 31.10 | Town |
| Parish | 17 | 2,371 | 2,392 | -0.17% | 57 | 41.73 | Town |
| Pulaski | 18 | 2,331 | 2,176 | 1.35% | 659 | 3.54 | Village |
| Phoenix | 19 | 2,187 | 2,222 | -0.32% | 1,868 | 1.17 | Village |
| Central Square | 20 | 1,826 | 1,860 | -0.38% | 958 | 1.91 | Village |
| Minetto | 21 | 1,608 | 1,636 | -0.31% | 279 | 5.76 | Town |
| Mexico | 22 | 1,545 | 1,574 | -0.39% | 720 | 2.15 | Village |
| Williamstown | 23 | 1,353 | 1,333 | 0.37% | 35 | 38.67 | Town |
| Amboy | 24 | 1,283 | 1,247 | 0.55% | 35 | 37.05 | Town |
| Fulton | 25 | 1,219 | 1,202 | 0.33% | 19 | 64.98 | Town |
| Orwell | 26 | 1,080 | 1,074 | 0.19% | 27 | 39.58 | Town |
| Cleveland | 27 | 727 | 736 | -0.27% | 643 | 1.13 | Village |
| Lacona | 28 | 664 | 674 | -0.3% | 597 | 1.11 | Village |
| Sandy Creek | 29 | 618 | 625 | -0.16% | 458 | 1.35 | Village |
| Hannibal | 30 | 534 | 543 | -0.37% | 464 | 1.15 | Village |
| Parish | 31 | 441 | 451 | -0.45% | 280 | 1.57 | Village |
Oswego is the largest city in Oswego County, with a population of 17,093.
Parish is the smallest city in Oswego County.
There are 31 cities in Oswego County, New York.