| Zip Code | City | Population ↓ |
|---|---|---|
| 8854 | Piscataway | 60,233 |
| 8861 | Perth Amboy | 58,136 |
| 8901 | New Brunswick | 56,870 |
| 8831 | Monroe Township | 54,229 |
| 8816 | East Brunswick | 49,027 |
| 8817 | Edison | 48,140 |
| 8902 | North Brunswick | 43,037 |
| 8857 | Old Bridge | 40,430 |
| 8820 | Edison | 39,565 |
| 7747 | Matawan | 32,749 |
| 7008 | Carteret | 25,170 |
| 8859 | Parlin | 24,487 |
| 7080 | South Plainfield | 24,256 |
| 8879 | South Amboy | 22,514 |
| 7095 | Woodbridge | 20,927 |
| 8536 | Plainsboro | 20,693 |
| 8872 | Sayreville | 19,613 |
| 8837 | Edison | 19,544 |
| 7067 | Colonia | 18,581 |
| 8830 | Iselin | 18,511 |
| 8840 | Metuchen | 18,075 |
| 8852 | Monmouth Junction | 18,068 |
| 7001 | Avenel | 17,211 |
| 8882 | South River | 16,081 |
| 8904 | Highland Park | 14,996 |
| 8846 | Middlesex | 14,525 |
| 8824 | Kendall Park | 13,297 |
| 8863 | Fords | 12,663 |
| 8512 | Cranbury | 12,519 |
| 8850 | Milltown | 8,410 |
| 8810 | Dayton | 8,361 |
| 8884 | Spotswood | 8,152 |
| 7064 | Port Reading | 4,031 |
| 8832 | Keasbey | 2,745 |
| 7077 | Sewaren | 2,695 |
| 8828 | Helmetta | 2,302 |
The data shown reflect ZCTAs from the US Census. As of 2024, there are 36 ZCTAs in Middlesex County, New Jersey (US Census).