| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density (/mi²) | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Delhi | 1 | 5,535 | 4,778 | -0.18% | 86 | 64 | Town |
| Sidney | 2 | 5,359 | 5,530 | -0.59% | 107 | 50 | Town |
| Walton | 3 | 5,117 | 5,252 | -0.33% | 53 | 97 | Town |
| Delhi | 4 | 3,714 | 2,782 | 5.33% | 1,169 | 3 | Village |
| Sidney | 5 | 3,565 | 3,706 | -0.64% | 1,498 | 2 | Village |
| Davenport | 6 | 2,921 | 2,951 | -0.38% | 57 | 52 | Town |
| Walton | 7 | 2,806 | 2,914 | -0.64% | 1,820 | 2 | Village |
| Hancock | 8 | 2,704 | 2,757 | -0.48% | 17 | 159 | Town |
| Franklin | 9 | 2,237 | 2,274 | -0.4% | 28 | 81 | Town |
| Roxbury | 10 | 2,190 | 2,240 | -0.59% | 25 | 87 | Town |
| Stamford | 11 | 1,973 | 1,990 | -0.05% | 41 | 49 | Town |
| Colchester | 12 | 1,733 | 1,767 | -0.69% | 13 | 137 | Town |
| Kortright | 13 | 1,499 | 1,538 | -0.6% | 24 | 62 | Town |
| Meredith | 14 | 1,493 | 1,494 | -0.33% | 26 | 58 | Town |
| Harpersfield | 15 | 1,421 | 1,446 | 0.14% | 34 | 42 | Town |
| Tompkins | 16 | 1,260 | 1,289 | -0.4% | 13 | 98 | Town |
| Masonville | 17 | 1,223 | 1,242 | -0.33% | 23 | 54 | Town |
| Franklin | 18 | 1,139 | 1,145 | 0% | 7.0 | 170 | Town |
| Hamden | 19 | 1,117 | 1,134 | -0.36% | 19 | 60 | Town |
| Andes | 20 | 1,093 | 1,123 | -0.55% | 10 | 109 | Town |
| Stamford | 21 | 1,028 | 1,063 | -0.58% | 771 | 1 | Village |
| Hancock | 22 | 879 | 913 | -0.68% | 561 | 2 | Village |
| Bovina | 23 | 629 | 653 | -0.79% | 14 | 44 | Town |
| Margaretville | 24 | 476 | 524 | -1.86% | 684 | 1 | Village |
| Hobart | 25 | 381 | 396 | -0.78% | 765 | 0 | Village |
| Franklin | 26 | 267 | 278 | -0.74% | 788 | 0 | Village |
| Fleischmanns | 27 | 221 | 231 | -0.9% | 337 | 1 | Village |
Delhi is the largest city in Delaware County, with a population of 5,535.
Fleischmanns is the smallest city in Delaware County, with a population of 221.
There are 27 cities in Delaware County, New York.