13 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 |
| Ewing | 3 | 37,078 | 37,290 | 1.67% | 2,438 | 15 | Township |
| West Windsor | 4 | 34,877 | 29,530 | 3.93% | 1,365 | 26 | Township |
| Princeton | 5 | 33,075 | 30,629 | 2.53% | 1,843 | 18 | Township |
| Lawrence | 6 | 32,786 | 33,053 | 0.61% | 1,509 | 22 | Township |
| East Windsor | 7 | 30,984 | 29,941 | 0.89% | 1,990 | 16 | Township |
| Hopewell | 8 | 18,530 | 17,442 | 1.68% | 319 | 58 | Township |
| Robbinsville | 9 | 16,632 | 15,442 | 2.16% | 814 | 20 | Township |
| Hightstown | 10 | 6,078 | 5,884 | 0.83% | 4,929 | 1 | Borough |
| Hopewell | 11 | 4,590 | 4,377 | 1.53% | 154 | 30 | Township |
| Pennington | 12 | 2,984 | 2,787 | 1.32% | 3,105 | 1 | Borough |
| Hopewell | 13 | 1,972 | 1,900 | 0.87% | 2,724 | 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 1,972.
There are 13 cities in Mercer County, New Jersey.