22 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Amsterdam | 1 | 18,025 | 18,195 | -0.19% | 3,069 | 6 | City |
| Amsterdam | 2 | 5,683 | 5,562 | 0.83% | 192 | 30 | Town |
| Minden | 3 | 4,178 | 4,164 | 0.1% | 82 | 51 | Town |
| Canajoharie | 4 | 3,615 | 3,651 | -0.14% | 85 | 43 | Town |
| Palatine | 5 | 3,201 | 3,197 | 0.13% | 78 | 41 | Town |
| Glen | 6 | 2,651 | 2,536 | 1.34% | 69 | 39 | Town |
| St. Johnsville | 7 | 2,560 | 2,582 | -0.08% | 152 | 17 | Town |
| Canajoharie | 8 | 2,036 | 2,078 | -0.39% | 1,530 | 1 | Village |
| Fort Plain | 9 | 1,976 | 2,013 | -0.35% | 1,469 | 1 | Village |
| Root | 10 | 1,976 | 2,015 | -0.35% | 39 | 51 | Town |
| Esperance | 11 | 1,800 | 1,805 | -0.17% | 92 | 20 | Town |
| St. Johnsville | 12 | 1,686 | 1,713 | -0.3% | 1,920 | 1 | Village |
| Charleston | 13 | 1,327 | 1,356 | -0.38% | 32 | 42 | Town |
| Hagaman | 14 | 1,102 | 1,126 | -0.45% | 736 | 1 | Village |
| Tribes Hill | 15 | 797 | 869 | -1.6% | 350 | 2 | CDP |
| Palatine Bridge | 16 | 781 | 801 | -0.51% | 848 | 1 | Village |
| Fultonville | 17 | 768 | 747 | 0.52% | 1,610 | 0 | Village |
| Fonda | 18 | 683 | 695 | -0.29% | 1,267 | 1 | Village |
| Nelliston | 19 | 563 | 568 | -0.18% | 510 | 1 | Village |
| Fort Johnson | 20 | 429 | 424 | 0.23% | 581 | 1 | Village |
| Esperance | 21 | 354 | 356 | 0% | 724 | 0 | Village |
| Ames | 22 | 136 | 140 | -0.73% | 1,038 | 0 | Village |
Amsterdam is the largest city in Montgomery County, with a population of 18,025.
Ames is the smallest city in Montgomery County, with a population of 136.
There are 22 cities in Montgomery County, New York.