40 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| German Flatts | 1 | 12,064 | 12,230 | -0.11% | 358 | 34 | Town |
| Herkimer | 2 | 9,513 | 9,550 | 0.05% | 300 | 32 | Town |
| Ilion | 3 | 7,532 | 7,664 | -0.36% | 3,021 | 2 | Village |
| Herkimer | 4 | 7,245 | 7,287 | -0.12% | 2,799 | 3 | Village |
| Frankfort | 5 | 6,881 | 6,990 | -0.12% | 189 | 36 | Town |
| Little Falls | 6 | 4,513 | 4,582 | -0.31% | 1,176 | 4 | City |
| Mohawk | 7 | 3,540 | 3,564 | 0% | 102 | 35 | Town |
| Schuyler | 8 | 3,255 | 3,302 | -0.15% | 82 | 40 | Town |
| Manheim | 9 | 3,051 | 3,082 | -0.03% | 105 | 29 | Town |
| Mohawk | 10 | 2,367 | 2,412 | -0.38% | 2,699 | 1 | Village |
| Frankfort | 11 | 2,284 | 2,321 | -0.35% | 2,252 | 1 | Village |
| Russia | 12 | 2,282 | 2,262 | 0.35% | 40 | 57 | Town |
| Poland | 13 | 2,164 | 2,209 | -0.18% | 59 | 37 | Town |
| Newport | 14 | 2,105 | 2,137 | -0.09% | 66 | 32 | Town |
| Dolgeville | 15 | 2,007 | 2,044 | -0.4% | 1,121 | 2 | Village |
| Winfield | 16 | 1,881 | 1,896 | -0.11% | 80 | 24 | Town |
| Salisbury | 17 | 1,841 | 1,830 | 0.27% | 17 | 107 | Town |
| Webb | 18 | 1,830 | 1,794 | 0.66% | 4 | 451 | Town |
| Columbia | 19 | 1,598 | 1,568 | 0.44% | 46 | 35 | Town |
| Little Falls | 20 | 1,473 | 1,497 | -0.14% | 66 | 22 | Town |
| Fairfield | 21 | 1,451 | 1,472 | -0.07% | 35 | 41 | Town |
| Litchfield | 22 | 1,435 | 1,442 | -0.07% | 48 | 30 | Town |
| Warren | 23 | 1,013 | 1,029 | -0.1% | 27 | 38 | Town |
| East Herkimer | 24 | 990 | 870 | 7.14% | 830 | 1 | CDP |
| Ohio | 25 | 980 | 964 | 0.51% | 3 | 301 | Town |
| Danube | 26 | 949 | 945 | -0.32% | 32 | 29 | Town |
| Norway | 27 | 761 | 744 | 1.06% | 21 | 36 | Town |
| West Winfield | 28 | 726 | 741 | -0.41% | 797 | 1 | Village |
| Stark | 29 | 706 | 715 | 0% | 22 | 32 | Town |
| East Frankfort | 30 | 624 | 559 | 7.22% | 788 | 1 | CDP |
| Newport | 31 | 554 | 563 | -0.36% | 1,053 | 1 | Village |
| Old Forge | 32 | 527 | 606 | -2.77% | 295 | 2 | CDP |
| Poland | 33 | 476 | 484 | -0.42% | 877 | 1 | Village |
| Middleville | 34 | 429 | 436 | -0.46% | 561 | 1 | Village |
| Salisbury Center | 35 | 319 | 269 | 7.05% | 349 | 1 | CDP |
| Thendara | 36 | 285 | 40 | 7.14% | 511 | 1 | CDP |
| Cold Brook | 37 | 259 | 267 | -0.77% | 590 | 0 | Village |
| Unadilla Forks | 38 | 249 | 221 | 7.33% | 50 | 5 | CDP |
| South Ilion | 39 | 246 | 178 | 6.96% | 560 | 0 | CDP |
| Otter Lake | 40 | 110 | 75 | 6.8% | 233 | 0 | CDP |
German Flatts is the largest city in Herkimer County, with a population of 12,064.
Otter Lake is the smallest city in Herkimer County, with a population of 110.
There are 40 cities in Herkimer County, New York.