| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density (/mi²) | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Brookhaven | 1 | 497,748 | 484,406 | 0.27% | 1,917 | 260 | Town |
| Islip | 2 | 340,934 | 339,081 | 0.02% | 3,304 | 103 | Town |
| Babylon | 3 | 219,919 | 217,605 | 0.07% | 4,207 | 52 | Town |
| Huntington | 4 | 206,155 | 203,600 | 0.13% | 2,192 | 94 | Town |
| Smithtown | 5 | 116,900 | 115,915 | 0.05% | 2,175 | 54 | Town |
| Southampton | 6 | 72,137 | 68,887 | 0.75% | 520 | 139 | Town |
| Riverhead | 7 | 36,495 | 35,887 | 0.28% | 541 | 67 | Town |
| East Hampton | 8 | 29,566 | 28,333 | 0.56% | 398 | 74 | Town |
| Lindenhurst | 9 | 27,304 | 27,085 | 0.17% | 7,287 | 4 | Village |
| Southold | 10 | 24,326 | 23,737 | 0.27% | 453 | 54 | Town |
| Patchogue | 11 | 12,519 | 12,362 | 0.26% | 5,539 | 2 | Village |
| Babylon | 12 | 12,299 | 12,133 | 0.15% | 5,101 | 2 | Village |
| Lake Grove | 13 | 11,199 | 11,018 | 0.28% | 3,801 | 3 | Village |
| Amityville | 14 | 9,871 | 9,464 | 0.73% | 4,801 | 2 | Village |
| Port Jefferson | 15 | 8,370 | 7,971 | 0.77% | 2,733 | 3 | Village |
| Northport | 16 | 7,338 | 7,331 | 0.03% | 3,186 | 2 | Village |
| Southampton | 17 | 4,772 | 4,536 | 0.89% | 732 | 7 | Village |
| Greenport | 18 | 4,325 | 4,455 | -0.28% | 232 | 19 | Town |
| Islandia | 19 | 3,757 | 3,586 | 0.64% | 1,697 | 2 | Village |
| Lloyd Harbor | 20 | 3,591 | 3,568 | 0.11% | 385 | 9 | Village |
| Shelter Island | 21 | 3,367 | 3,236 | 0.48% | 276 | 12 | Town |
| Brightwaters | 22 | 3,212 | 3,191 | 0.12% | 3,325 | 1 | Village |
| Sag Harbor | 23 | 2,860 | 2,748 | 0.67% | 1,600 | 2 | Village |
| Greenport | 24 | 2,590 | 2,588 | 0% | 2,726 | 1 | Village |
| Westhampton Beach | 25 | 2,286 | 2,192 | 0.57% | 778 | 3 | Village |
| Bellport | 26 | 2,226 | 2,195 | 0.27% | 1,535 | 1 | Village |
| Village of the Branch | 27 | 1,764 | 1,763 | 0% | 1,857 | 1 | Village |
| Quogue | 28 | 1,719 | 1,625 | 0.94% | 412 | 4 | Village |
| Nissequogue | 29 | 1,645 | 1,603 | 0.43% | 432 | 4 | Village |
| East Hampton | 30 | 1,567 | 1,480 | 0.97% | 329 | 5 | Village |
| Head of the Harbor | 31 | 1,482 | 1,477 | 0.07% | 528 | 3 | Village |
| Huntington Bay | 32 | 1,465 | 1,431 | 0.41% | 1,468 | 1 | Village |
| North Haven | 33 | 1,229 | 1,151 | 1.15% | 463 | 3 | Village |
| Old Field | 34 | 952 | 906 | 0.53% | 460 | 2 | Village |
| Poquott | 35 | 933 | 928 | 0.11% | 2,130 | 0 | Village |
| Belle Terre | 36 | 798 | 784 | 0.25% | 902 | 1 | Village |
| Sagaponack | 37 | 755 | 732 | 0.4% | 171 | 4 | Village |
| Asharoken | 38 | 628 | 603 | 0.64% | 442 | 1 | Village |
| Shoreham | 39 | 531 | 525 | 0.19% | 1,170 | 0 | Village |
| Ocean Beach | 40 | 176 | 169 | 0.57% | 1,248 | 0 | Village |
| West Hampton Dunes | 41 | 121 | 112 | 0.83% | 387 | 0 | Village |
| Saltaire | 42 | 111 | 109 | 0% | 476 | 0 | Village |
| Dering Harbor | 43 | 36 | 35 | 0% | 146 | 0 | Village |
Brookhaven is the largest city in Suffolk County, with a population of 497,748.
Dering Harbor is the smallest city in Suffolk County, with a population of 36.
There are 43 cities in Suffolk County, New York.