43 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Brookhaven | 1 | 495,150 | 484,592 | 0.49% | 1,907 | 260 | Town |
| Islip | 2 | 340,300 | 339,101 | 0.33% | 3,298 | 103 | Town |
| Babylon | 3 | 219,305 | 217,662 | 0.34% | 4,195 | 52 | Town |
| Huntington | 4 | 205,743 | 203,614 | 0.51% | 2,188 | 94 | Town |
| Smithtown | 5 | 116,584 | 115,898 | 0.31% | 2,169 | 54 | Town |
| Southampton | 6 | 71,297 | 68,869 | 0.92% | 514 | 139 | Town |
| Riverhead | 7 | 36,235 | 35,864 | 0.47% | 538 | 67 | Town |
| East Hampton | 8 | 29,320 | 28,342 | 0.79% | 394 | 74 | Town |
| Lindenhurst | 9 | 27,177 | 27,092 | 0.06% | 7,253 | 4 | Village |
| Southold | 10 | 24,224 | 23,742 | 0.59% | 451 | 54 | Town |
| Patchogue | 11 | 12,465 | 12,374 | 0.14% | 5,515 | 2 | Village |
| Babylon | 12 | 12,199 | 12,168 | 0.05% | 5,060 | 2 | Village |
| Lake Grove | 13 | 11,126 | 11,039 | 0.15% | 3,777 | 3 | Village |
| Amityville | 14 | 9,779 | 9,471 | 0.63% | 4,756 | 2 | Village |
| Port Jefferson | 15 | 8,244 | 7,969 | 0.67% | 2,691 | 3 | Village |
| Northport | 16 | 7,313 | 7,330 | -0.05% | 3,175 | 2 | Village |
| Southampton | 17 | 4,730 | 4,544 | 0.79% | 726 | 7 | Village |
| Greenport | 18 | 4,307 | 4,461 | -0.99% | 231 | 19 | Town |
| Islandia | 19 | 3,672 | 3,566 | 0.58% | 1,659 | 2 | Village |
| Lloyd Harbor | 20 | 3,565 | 3,565 | 0% | 382 | 9 | Village |
| Shelter Island | 21 | 3,345 | 3,235 | 0.87% | 274 | 12 | Town |
| Brightwaters | 22 | 3,188 | 3,182 | 0.03% | 3,300 | 1 | Village |
| Sag Harbor | 23 | 2,832 | 2,752 | 0.57% | 1,585 | 2 | Village |
| Greenport | 24 | 2,589 | 2,597 | -0.08% | 2,725 | 1 | Village |
| Westhampton Beach | 25 | 2,248 | 2,197 | 0.45% | 765 | 3 | Village |
| Bellport | 26 | 2,214 | 2,198 | 0.14% | 1,527 | 1 | Village |
| Village of the Branch | 27 | 1,761 | 1,768 | -0.11% | 1,854 | 1 | Village |
| Quogue | 28 | 1,712 | 1,636 | 0.88% | 411 | 4 | Village |
| Nissequogue | 29 | 1,630 | 1,603 | 0.31% | 428 | 4 | Village |
| East Hampton | 30 | 1,570 | 1,500 | 0.9% | 329 | 5 | Village |
| Head of the Harbor | 31 | 1,474 | 1,479 | -0.07% | 525 | 3 | Village |
| Huntington Bay | 32 | 1,450 | 1,424 | 0.35% | 1,453 | 1 | Village |
| North Haven | 33 | 1,209 | 1,148 | 1% | 456 | 3 | Village |
| Old Field | 34 | 929 | 908 | 0.43% | 449 | 2 | Village |
| Poquott | 35 | 929 | 927 | 0% | 2,121 | 0 | Village |
| Belle Terre | 36 | 789 | 783 | 0.13% | 892 | 1 | Village |
| Sagaponack | 37 | 746 | 733 | 0.27% | 169 | 4 | Village |
| Asharoken | 38 | 611 | 593 | 0.49% | 430 | 1 | Village |
| Shoreham | 39 | 525 | 520 | 0.19% | 1,156 | 0 | Village |
| Ocean Beach | 40 | 176 | 171 | 0.57% | 1,248 | 0 | Village |
| West Hampton Dunes | 41 | 120 | 112 | 0.84% | 383 | 0 | Village |
| Saltaire | 42 | 109 | 107 | 0% | 468 | 0 | Village |
| Dering Harbor | 43 | 37 | 36 | 0% | 150 | 0 | Village |
Brookhaven is the largest city in Suffolk County, with a population of 495,150.
Dering Harbor is the smallest city in Suffolk County, with a population of 37.
There are 43 cities in Suffolk County, New York.