28 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| German Flatts | 1 | 12,009 | 12,239 | -0.29% | 356 | 33.70 | Town |
| Herkimer | 2 | 9,393 | 9,550 | -0.5% | 297 | 31.66 | Town |
| Ilion | 3 | 7,499 | 7,669 | -0.45% | 3,008 | 2.49 | Village |
| Herkimer | 4 | 7,201 | 7,286 | -0.24% | 2,782 | 2.59 | Village |
| Frankfort | 5 | 6,852 | 6,992 | -0.28% | 188 | 36.43 | Town |
| Little Falls | 6 | 4,472 | 4,581 | -0.49% | 1,165 | 3.84 | City |
| Mohawk | 7 | 3,509 | 3,565 | -0.28% | 101 | 34.68 | Town |
| Schuyler | 8 | 3,239 | 3,301 | -0.25% | 81 | 39.87 | Town |
| Manheim | 9 | 3,030 | 3,080 | -0.23% | 104 | 29.14 | Town |
| Mohawk | 10 | 2,353 | 2,415 | -0.51% | 2,683 | 0.88 | Village |
| Russia | 11 | 2,286 | 2,265 | 0.4% | 40 | 56.96 | Town |
| Frankfort | 12 | 2,266 | 2,323 | -0.48% | 2,235 | 1.01 | Village |
| Poland | 13 | 2,177 | 2,209 | 0.14% | 60 | 36.50 | Town |
| Newport | 14 | 2,097 | 2,142 | -0.29% | 66 | 32.01 | Town |
| Dolgeville | 15 | 1,993 | 2,045 | -0.5% | 1,113 | 1.79 | Village |
| Winfield | 16 | 1,883 | 1,894 | 0% | 80 | 23.64 | Town |
| Salisbury | 17 | 1,831 | 1,827 | 0.16% | 17 | 107.37 | Town |
| Webb | 18 | 1,822 | 1,796 | 0.44% | 4 | 451.40 | Town |
| Columbia | 19 | 1,604 | 1,567 | 0.75% | 46 | 35.07 | Town |
| Little Falls | 20 | 1,465 | 1,496 | -0.27% | 66 | 22.34 | Town |
| Litchfield | 21 | 1,443 | 1,442 | 0.21% | 48 | 29.99 | Town |
| Fairfield | 22 | 1,440 | 1,469 | -0.28% | 35 | 41.30 | Town |
| Warren | 23 | 1,016 | 1,033 | -0.2% | 27 | 38.05 | Town |
| West Winfield | 24 | 728 | 745 | -0.41% | 799 | 0.91 | Village |
| Newport | 25 | 550 | 562 | -0.36% | 1,046 | 0.53 | Village |
| Poland | 26 | 478 | 488 | -0.42% | 880 | 0.54 | Village |
| Middleville | 27 | 424 | 434 | -0.47% | 554 | 0.77 | Village |
| Cold Brook | 28 | 256 | 266 | -0.78% | 583 | 0.44 | Village |
German Flatts is the largest city in Herkimer County, with a population of 12,009.
Cold Brook is the smallest city in Herkimer County.
There are 28 cities in Herkimer County, New York.