| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density (/mi²) | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Bridgewater | 1 | 46,345 | 45,815 | -0.24% | 1,453 | 32 | Township |
| Hillsborough | 2 | 45,037 | 43,201 | -0.05% | 825 | 55 | Township |
| Bernards | 3 | 28,557 | 27,768 | -0.13% | 1,180 | 24 | Township |
| Raritan | 4 | 25,406 | 23,521 | 0.49% | 678 | 37 | Township |
| Montgomery | 5 | 23,982 | 23,629 | -0.24% | 742 | 32 | Township |
| North Plainfield | 6 | 22,830 | 22,745 | -0.21% | 8,133 | 3 | Borough |
| Warren | 7 | 18,787 | 15,871 | 5.82% | 960 | 20 | Township |
| Branchburg | 8 | 15,498 | 14,899 | -0.08% | 772 | 20 | Township |
| Somerville | 9 | 14,987 | 12,357 | 2.2% | 6,410 | 2 | Borough |
| Bound Brook | 10 | 13,507 | 11,954 | 3.6% | 8,132 | 2 | Borough |
| Manville | 11 | 10,909 | 10,925 | -0.21% | 4,620 | 2 | Borough |
| Raritan | 12 | 8,504 | 7,817 | -0.14% | 4,269 | 2 | Borough |
| Bedminster | 13 | 8,269 | 8,245 | -0.19% | 317 | 26 | Township |
| Bernardsville | 14 | 7,973 | 7,869 | 0.09% | 621 | 13 | Borough |
| Green Brook | 15 | 7,399 | 7,276 | -0.15% | 1,679 | 4 | Township |
| Watchung | 16 | 6,566 | 6,437 | -0.26% | 1,091 | 6 | Borough |
| South Bound Brook | 17 | 4,915 | 4,854 | -0.22% | 7,620 | 1 | Borough |
| Peapack and Gladstone | 18 | 2,584 | 2,556 | -0.12% | 451 | 6 | Borough |
| Far Hills | 19 | 1,014 | 927 | 4.11% | 209 | 5 | Borough |
| Rocky Hill | 20 | 752 | 739 | 0.13% | 1,233 | 1 | Borough |
| Millstone | 21 | 455 | 454 | -0.22% | 668 | 1 | Borough |
Bridgewater is the largest city in Somerset County, with a population of 46,345.
Millstone is the smallest city in Somerset County, with a population of 455.
There are 21 cities in Somerset County, New Jersey.