| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density (/mi²) | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Hamilton | 1 | 94,267 | 92,030 | 0.12% | 2,390 | 39 | Township |
| Trenton | 2 | 91,702 | 90,549 | 0.21% | 12,057 | 8 | City |
| Ewing | 3 | 39,278 | 37,295 | 0.64% | 2,583 | 15 | Township |
| Lawrence | 4 | 34,268 | 33,042 | 0.3% | 1,577 | 22 | Township |
| West Windsor | 5 | 33,406 | 29,495 | 1.73% | 1,308 | 26 | Township |
| Princeton | 6 | 31,492 | 30,625 | 0.07% | 1,755 | 18 | Township |
| East Windsor | 7 | 30,607 | 29,960 | 0.15% | 1,966 | 16 | Township |
| Hopewell | 8 | 19,373 | 17,487 | 3.25% | 334 | 58 | Township |
| Robbinsville | 9 | 15,986 | 15,412 | 0.18% | 782 | 20 | Township |
| Hightstown | 10 | 6,026 | 5,885 | 0.32% | 4,887 | 1 | Borough |
| Hopewell | 11 | 4,561 | 4,384 | 0.97% | 153 | 30 | Township |
| Pennington | 12 | 2,897 | 2,755 | 0.28% | 3,015 | 1 | Borough |
| Hopewell | 13 | 1,947 | 1,899 | 0.15% | 2,689 | 1 | Borough |
Hamilton is the largest city in Mercer County, with a population of 94,267.
Hopewell is the smallest city in Mercer County, with a population of 1,947.
There are 13 cities in Mercer County, New Jersey.