| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density (/mi²) | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| German Flatts | 1 | 11,925 | 12,223 | -0.37% | 354 | 34 | Town |
| Herkimer | 2 | 9,401 | 9,547 | -0.33% | 297 | 32 | Town |
| Ilion | 3 | 7,452 | 7,663 | -0.48% | 2,989 | 2 | Village |
| Herkimer | 4 | 7,177 | 7,292 | -0.25% | 2,773 | 3 | Village |
| Frankfort | 5 | 6,821 | 7,003 | -0.38% | 187 | 36 | Town |
| Little Falls | 6 | 4,462 | 4,577 | -0.42% | 1,163 | 4 | City |
| Mohawk | 7 | 3,552 | 3,565 | 0.2% | 102 | 35 | Town |
| Schuyler | 8 | 3,257 | 3,307 | -0.18% | 82 | 40 | Town |
| Manheim | 9 | 3,017 | 3,080 | -0.3% | 104 | 29 | Town |
| Mohawk | 10 | 2,338 | 2,407 | -0.51% | 2,666 | 1 | Village |
| Russia | 11 | 2,270 | 2,267 | 0.04% | 40 | 57 | Town |
| Frankfort | 12 | 2,264 | 2,325 | -0.48% | 2,233 | 1 | Village |
| Poland | 13 | 2,168 | 2,217 | -0.37% | 59 | 37 | Town |
| Newport | 14 | 2,083 | 2,137 | -0.38% | 65 | 32 | Town |
| Dolgeville | 15 | 1,981 | 2,043 | -0.55% | 1,106 | 2 | Village |
| Winfield | 16 | 1,855 | 1,892 | -0.32% | 78 | 24 | Town |
| Salisbury | 17 | 1,841 | 1,830 | 0.22% | 17 | 107 | Town |
| Webb | 18 | 1,814 | 1,796 | 0.06% | 4.0 | 451 | Town |
| Columbia | 19 | 1,581 | 1,568 | -0.19% | 45 | 35 | Town |
| Little Falls | 20 | 1,477 | 1,509 | -0.27% | 66 | 22 | Town |
| Fairfield | 21 | 1,429 | 1,473 | -0.49% | 35 | 41 | Town |
| Litchfield | 22 | 1,427 | 1,437 | -0.07% | 48 | 30 | Town |
| Warren | 23 | 1,025 | 1,033 | 0.39% | 27 | 38 | Town |
| Ohio | 24 | 974 | 964 | 0.1% | 3.0 | 301 | Town |
| Danube | 25 | 959 | 946 | 0.42% | 33 | 29 | Town |
| Norway | 26 | 757 | 740 | 0.53% | 21 | 36 | Town |
| West Winfield | 27 | 720 | 741 | -0.55% | 790 | 1 | Village |
| Stark | 28 | 696 | 714 | -0.43% | 22 | 32 | Town |
| Newport | 29 | 547 | 561 | -0.55% | 1,040 | 1 | Village |
| Poland | 30 | 471 | 486 | -0.63% | 867 | 1 | Village |
| Middleville | 31 | 424 | 438 | -0.47% | 554 | 1 | Village |
| Cold Brook | 32 | 253 | 263 | -0.78% | 576 | 0 | Village |
German Flatts is the largest city in Herkimer County, with a population of 11,925.
Cold Brook is the smallest city in Herkimer County, with a population of 253.
There are 32 cities in Herkimer County, New York.