27 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Delhi | 1 | 5,373 | 4,782 | -0.06% | 84 | 64 | Town |
| Sidney | 2 | 5,357 | 5,526 | -0.94% | 107 | 50 | Town |
| Walton | 3 | 5,088 | 5,258 | -1.01% | 53 | 97 | Town |
| Sidney | 4 | 3,590 | 3,705 | -0.64% | 1,508 | 2 | Village |
| Delhi | 5 | 3,507 | 2,779 | 4.31% | 1,104 | 3 | Village |
| Davenport | 6 | 2,904 | 2,943 | -0.58% | 56 | 52 | Town |
| Walton | 7 | 2,826 | 2,914 | -0.63% | 1,833 | 2 | Village |
| Hancock | 8 | 2,702 | 2,757 | -0.77% | 17 | 159 | Town |
| Franklin | 9 | 2,244 | 2,285 | -0.66% | 28 | 81 | Town |
| Roxbury | 10 | 2,198 | 2,245 | -0.9% | 25 | 87 | Town |
| Stamford | 11 | 1,968 | 1,995 | -0.51% | 41 | 49 | Town |
| Colchester | 12 | 1,750 | 1,775 | -0.79% | 13 | 137 | Town |
| Kortright | 13 | 1,495 | 1,543 | -1.06% | 24 | 62 | Town |
| Meredith | 14 | 1,481 | 1,488 | -0.67% | 25 | 58 | Town |
| Harpersfield | 15 | 1,401 | 1,448 | -0.99% | 33 | 42 | Town |
| Tompkins | 16 | 1,246 | 1,289 | -1.03% | 13 | 98 | Town |
| Masonville | 17 | 1,217 | 1,239 | -0.81% | 22 | 54 | Town |
| Franklin | 18 | 1,142 | 1,146 | -0.09% | 7 | 170 | Town |
| Hamden | 19 | 1,111 | 1,133 | -0.63% | 19 | 60 | Town |
| Andes | 20 | 1,085 | 1,117 | -1% | 10 | 109 | Town |
| Stamford | 21 | 1,058 | 1,085 | -0.56% | 794 | 1 | Village |
| Hancock | 22 | 884 | 914 | -0.67% | 564 | 2 | Village |
| Bovina | 23 | 633 | 657 | -1.09% | 14 | 44 | Town |
| Margaretville | 24 | 482 | 529 | -2.03% | 693 | 1 | Village |
| Hobart | 25 | 384 | 398 | -0.78% | 771 | 0 | Village |
| Franklin | 26 | 271 | 280 | -0.73% | 799 | 0 | Village |
| Fleischmanns | 27 | 224 | 233 | -0.88% | 342 | 1 | Village |
Delhi is the largest city in Delaware County, with a population of 5,373.
Fleischmanns is the smallest city in Delaware County, with a population of 224.
There are 27 cities in Delaware County, New York.