31 cities
| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Bridgewater | 1 | 48,127 | 45,878 | 1.32% | 1,509 | 32 | Township |
| Hillsborough | 2 | 47,159 | 43,242 | 1.88% | 863 | 55 | Township |
| Bernards | 3 | 29,436 | 27,769 | 1.23% | 1,216 | 24 | Township |
| Raritan | 4 | 26,408 | 23,532 | 2.17% | 705 | 37 | Township |
| Montgomery | 5 | 24,884 | 23,635 | 1.28% | 770 | 32 | Township |
| North Plainfield | 6 | 23,660 | 22,749 | 1.26% | 8,429 | 3 | Borough |
| Warren | 7 | 17,845 | 15,886 | 2.96% | 912 | 20 | Township |
| Branchburg | 8 | 16,079 | 14,900 | 1.45% | 801 | 20 | Township |
| Somerville | 9 | 15,463 | 12,357 | 3.47% | 6,614 | 2 | Borough |
| Somerville | 10 | 14,802 | 12,357 | 1.28% | 6,331 | 2 | Borough |
| Bound Brook | 11 | 12,988 | 11,952 | 1.35% | 7,819 | 2 | Borough |
| Bound Brook | 12 | 12,963 | 11,952 | 1.25% | 7,804 | 2 | Borough |
| Manville | 13 | 11,329 | 10,932 | 1.33% | 4,798 | 2 | Borough |
| Manville | 14 | 11,080 | 10,932 | 0.23% | 4,693 | 2 | Borough |
| Raritan | 15 | 8,966 | 7,820 | 2.18% | 4,501 | 2 | Borough |
| Raritan | 16 | 8,752 | 7,820 | 0.97% | 4,394 | 2 | Borough |
| Bedminster | 17 | 8,560 | 8,250 | 1.21% | 328 | 26 | Township |
| Bernardsville | 18 | 8,240 | 7,881 | 1.35% | 642 | 13 | Borough |
| Bernardsville | 19 | 8,089 | 7,881 | 0.43% | 630 | 13 | Borough |
| Green Brook | 20 | 7,631 | 7,262 | 1.19% | 1,732 | 4 | Township |
| Watchung | 21 | 6,824 | 6,443 | 1.62% | 1,134 | 6 | Borough |
| Watchung | 22 | 6,687 | 6,443 | 0.62% | 1,112 | 6 | Borough |
| South Bound Brook | 23 | 5,181 | 4,853 | 2.13% | 8,033 | 1 | Borough |
| South Bound Brook | 24 | 5,021 | 4,853 | 0.56% | 7,784 | 1 | Borough |
| Peapack and Gladstone | 25 | 2,688 | 2,553 | 1.63% | 469 | 6 | Borough |
| Far Hills | 26 | 959 | 922 | 1.27% | 198 | 5 | Borough |
| Far Hills | 27 | 941 | 922 | 0.32% | 194 | 5 | Borough |
| Rocky Hill | 28 | 773 | 740 | 1.18% | 1,267 | 1 | Borough |
| Rocky Hill | 29 | 762 | 740 | 0.53% | 1,249 | 1 | Borough |
| Millstone | 30 | 467 | 449 | 1.3% | 686 | 1 | Borough |
| Millstone | 31 | 458 | 449 | 0.44% | 673 | 1 | Borough |
Bridgewater is the largest city in Somerset County, with a population of 48,127.
Millstone is the smallest city in Somerset County, with a population of 458.
There are 31 cities in Somerset County, New Jersey.