18 cities
| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Hamilton | 1 | 96,013 | 92,048 | 1.11% | 2,434 | 39 | Township |
| Trenton | 2 | 92,813 | 90,546 | 0.88% | 12,203 | 8 | City |
| Trenton | 3 | 91,516 | 90,546 | 0.18% | 12,032 | 8 | City |
| Ewing | 4 | 37,078 | 37,290 | 1.67% | 2,438 | 15 | Township |
| West Windsor | 5 | 34,877 | 29,530 | 3.93% | 1,365 | 26 | Township |
| Princeton | 6 | 33,075 | 30,629 | 2.53% | 1,843 | 18 | Township |
| Lawrence | 7 | 32,786 | 33,053 | 0.61% | 1,509 | 22 | Township |
| Princeton | 8 | 31,853 | 30,629 | 0.64% | 1,775 | 18 | Township |
| East Windsor | 9 | 30,984 | 29,941 | 0.89% | 1,990 | 16 | Township |
| Hopewell | 10 | 18,530 | 17,442 | 1.68% | 319 | 58 | Township |
| Robbinsville | 11 | 16,632 | 15,442 | 2.16% | 814 | 20 | Township |
| Hightstown | 12 | 6,078 | 5,884 | 0.83% | 4,929 | 1 | Borough |
| Hightstown | 13 | 6,025 | 5,884 | 0.4% | 4,886 | 1 | Borough |
| Hopewell | 14 | 4,590 | 4,377 | 1.53% | 154 | 30 | Township |
| Pennington | 15 | 2,984 | 2,787 | 1.32% | 3,105 | 1 | Borough |
| Pennington | 16 | 2,965 | 2,787 | 1.02% | 3,085 | 1 | Borough |
| Hopewell | 17 | 1,972 | 1,900 | 0.87% | 2,724 | 1 | Borough |
| Hopewell | 18 | 1,957 | 1,900 | 0.51% | 2,703 | 1 | Borough |
Hamilton is the largest city in Mercer County, with a population of 96,013.
Hopewell is the smallest city in Mercer County, with a population of 1,957.
There are 18 cities in Mercer County, New Jersey.