Note: As defined by the US Census Bureau, a city's official boundaries often extend miles beyond the city itself and may even cross county lines. As such, several thousand US cities officially exist in two or more counties (and therefore appear on multiple counties' lists of cities.)
City | Rank | 2024 Pop. | 2020 Pop. | Change | Density (/mi²) | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Franklin township | 1 | 67,981 | 68,312 | -0.37% | 1,472 | 46.2 | Township |
| Bridgewater township | 2 | 45,616 | 45,870 | -0.43% | 1,431 | 31.9 | Township |
| Hillsborough township | 3 | 44,544 | 43,233 | 0.93% | 816 | 54.6 | Township |
| Bernards township | 4 | 28,299 | 27,765 | 0.71% | 1,169 | 24.2 | Township |
| Montgomery township | 5 | 23,855 | 23,635 | 0.57% | 739 | 32.3 | Township |
| North Plainfield borough | 6 | 22,498 | 22,748 | -0.3% | 8,015 | 2.8 | Borough |
| Warren township | 7 | 16,382 | 15,884 | 1.41% | 837 | 19.6 | Township |
| Branchburg township | 8 | 15,629 | 14,899 | 2.51% | 779 | 20.1 | Township |
| Somerville borough | 9 | 14,862 | 12,359 | 5.32% | 6,357 | 2.3 | Borough |
| Bound Brook borough | 10 | 12,787 | 11,954 | 3.36% | 7,698 | 1.7 | Borough |
| Manville borough | 11 | 10,718 | 10,932 | -0.57% | 4,540 | 2.4 | Borough |
| Raritan borough | 12 | 8,392 | 7,820 | -0.36% | 4,213 | 2.0 | Borough |
| Bedminster township | 13 | 8,156 | 8,250 | -0.28% | 312 | 26.1 | Township |
| Bernardsville borough | 14 | 7,817 | 7,881 | -0.26% | 609 | 12.8 | Borough |
| Green Brook township | 15 | 7,267 | 7,259 | -0.33% | 1,649 | 4.4 | Township |
| Watchung borough | 16 | 6,428 | 6,437 | -0.09% | 1,068 | 6.0 | Borough |
| South Bound Brook borough | 17 | 4,790 | 4,851 | -0.44% | 7,426 | 0.6 | Borough |
| Peapack and Gladstone borough | 18 | 2,523 | 2,552 | -0.59% | 440 | 5.7 | Borough |
Note: City markers shown outside the county boundary mean that a part of the city extends into this county, but is primarily located in an adjacent county.
Franklin township is the largest city in Somerset County.
Peapack and Gladstone borough is the smallest city in Somerset County.
There are 18 cities in Somerset County, New Jersey.