| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density (/mi²) | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Niagara Falls | 1 | 46,981 | 48,560 | -0.58% | 3,336 | 14 | City |
| North Tonawanda | 2 | 29,676 | 30,435 | -0.44% | 2,940 | 10 | City |
| Lockport | 3 | 20,690 | 20,501 | 0.24% | 461 | 45 | Town |
| Lockport | 4 | 20,127 | 20,827 | -0.6% | 2,396 | 8 | City |
| Wheatfield | 5 | 18,558 | 18,564 | 0.02% | 665 | 28 | Town |
| Lewiston | 6 | 15,652 | 15,912 | -0.15% | 422 | 37 | Town |
| Newfane | 7 | 9,111 | 9,254 | -0.31% | 176 | 52 | Town |
| Niagara | 8 | 7,643 | 7,839 | -0.33% | 806 | 9 | Town |
| Royalton | 9 | 7,418 | 7,504 | -0.09% | 106 | 70 | Town |
| Pendleton | 10 | 7,118 | 7,027 | -0.03% | 263 | 27 | Town |
| Porter | 11 | 6,462 | 6,502 | 0.22% | 195 | 33 | Town |
| Cambria | 12 | 5,729 | 5,748 | 0.03% | 144 | 40 | Town |
| Wilson | 13 | 5,705 | 5,834 | -0.38% | 115 | 49 | Town |
| Hartland | 14 | 3,797 | 3,873 | -0.16% | 72 | 52 | Town |
| Somerset | 15 | 2,544 | 2,596 | -0.2% | 69 | 37 | Town |
| Lewiston | 16 | 2,482 | 2,538 | -0.4% | 2,263 | 1 | Village |
| Barker | 17 | 2,459 | 2,506 | 0.04% | 59 | 41 | Town |
| Youngstown | 18 | 1,814 | 1,859 | -0.44% | 1,678 | 1 | Village |
| Middleport | 19 | 1,681 | 1,742 | -0.65% | 1,928 | 1 | Village |
| Wilson | 20 | 1,204 | 1,241 | -0.5% | 1,481 | 1 | Village |
| Barker | 21 | 562 | 583 | -0.71% | 1,338 | 0 | Village |
Niagara Falls is the largest city in Niagara County, with a population of 46,981.
Barker is the smallest city in Niagara County, with a population of 562.
There are 21 cities in Niagara County, New York.