| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density (/mi²) | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Oswego | 1 | 17,039 | 16,910 | 0.09% | 2,238 | 8 | City |
| Fulton | 2 | 11,145 | 11,364 | -0.38% | 2,841 | 4 | City |
| Hastings | 3 | 9,492 | 9,336 | 0.57% | 208 | 46 | Town |
| Oswego | 4 | 8,524 | 7,911 | 0.22% | 312 | 27 | Town |
| Schroeppel | 5 | 7,977 | 7,963 | 0.26% | 189 | 42 | Town |
| Scriba | 6 | 6,631 | 6,616 | 0.05% | 163 | 41 | Town |
| Granby | 7 | 6,531 | 6,524 | 0.05% | 147 | 45 | Town |
| Richland | 8 | 5,832 | 5,619 | 0.78% | 102 | 57 | Town |
| Volney | 9 | 5,672 | 5,668 | 0.21% | 118 | 48 | Town |
| Mexico | 10 | 5,383 | 5,261 | 0.49% | 116 | 46 | Town |
| Constantia | 11 | 4,821 | 4,773 | 0.4% | 85 | 57 | Town |
| Hannibal | 12 | 4,527 | 4,518 | 0.38% | 101 | 45 | Town |
| West Monroe | 13 | 4,109 | 4,092 | 0.46% | 122 | 34 | Town |
| Sandy Creek | 14 | 3,838 | 3,810 | 0.37% | 91 | 42 | Town |
| Palermo | 15 | 3,437 | 3,458 | 0% | 85 | 40 | Town |
| New Haven | 16 | 3,028 | 2,928 | 0.77% | 97 | 31 | Town |
| Parish | 17 | 2,414 | 2,399 | 0.58% | 58 | 42 | Town |
| Pulaski | 18 | 2,290 | 2,173 | 0.93% | 648 | 4 | Village |
| Phoenix | 19 | 2,184 | 2,221 | -0.36% | 1,865 | 1 | Village |
| Central Square | 20 | 1,848 | 1,857 | -0.22% | 970 | 2 | Village |
| Minetto | 21 | 1,613 | 1,637 | 0% | 280 | 6 | Town |
| Mexico | 22 | 1,548 | 1,572 | -0.32% | 722 | 2 | Village |
| Williamstown | 23 | 1,364 | 1,335 | 0.59% | 35 | 39 | Town |
| Amboy | 24 | 1,326 | 1,245 | 1.61% | 36 | 37 | Town |
| Fulton | 25 | 1,200 | 1,203 | -0.41% | 18 | 65 | Town |
| Orwell | 26 | 1,090 | 1,067 | 0.83% | 28 | 40 | Town |
| Cleveland | 27 | 727 | 736 | -0.27% | 643 | 1 | Village |
| Lacona | 28 | 661 | 665 | -0.15% | 594 | 1 | Village |
| Sandy Creek | 29 | 616 | 625 | -0.32% | 457 | 1 | Village |
| Hannibal | 30 | 534 | 542 | -0.37% | 464 | 1 | Village |
| Boylston | 31 | 527 | 505 | 0.57% | 13 | 39 | Town |
| Redfield | 32 | 483 | 473 | 0.21% | 5.0 | 90 | Town |
| Parish | 33 | 443 | 453 | -0.45% | 281 | 2 | Village |
Oswego is the largest city in Oswego County, with a population of 17,039.
Parish is the smallest city in Oswego County, with a population of 443.
There are 33 cities in Oswego County, New York.