| Zip Code | City | Population ↓ |
|---|---|---|
| 1453 | Leominster | 43,550 |
| 1420 | Fitchburg | 41,661 |
| 1604 | Worcester | 40,724 |
| 1545 | Shrewsbury | 38,734 |
| 1605 | Worcester | 30,590 |
| 1757 | Milford | 30,411 |
| 1610 | Worcester | 27,033 |
| 1602 | Worcester | 25,869 |
| 1609 | Worcester | 23,256 |
| 1606 | Worcester | 22,636 |
| 1581 | Westborough | 21,360 |
| 1440 | Gardner | 21,231 |
| 1603 | Worcester | 20,678 |
| 1570 | Webster | 17,671 |
| 1550 | Southbridge | 17,669 |
| 1520 | Holden | 16,893 |
| 1501 | Auburn | 16,763 |
| 1532 | Northborough | 15,647 |
| 1510 | Clinton | 15,347 |
| 1569 | Uxbridge | 14,039 |
| 1527 | Millbury | 13,852 |
| 1331 | Athol | 13,845 |
| 1507 | Charlton | 13,338 |
| 1562 | Spencer | 11,955 |
| 1571 | Dudley | 11,885 |
| 1462 | Lunenburg | 11,765 |
| 1540 | Oxford | 11,420 |
| 1588 | Whitinsville | 10,468 |
| 1475 | Winchendon | 10,180 |
| 1772 | Southborough | 9,867 |
| 1590 | Sutton | 9,268 |
| 1516 | Douglas | 9,213 |
| 1504 | Blackstone | 9,195 |
| 1543 | Rutland | 9,102 |
| 1607 | Worcester | 8,630 |
| 1523 | Lancaster | 8,395 |
| 1473 | Westminster | 8,220 |
| 1564 | Sterling | 8,053 |
| 1568 | Upton | 7,828 |
| 1519 | Grafton | 7,634 |
| 1583 | West Boylston | 7,476 |
| 1536 | North Grafton | 7,282 |
| 1566 | Sturbridge | 6,795 |
| 1430 | Ashburnham | 6,457 |
| 1756 | Mendon | 6,238 |
| 1524 | Leicester | 6,077 |
| 1747 | Hopedale | 6,021 |
| 1534 | Northbridge | 5,893 |
| 1740 | Bolton | 5,653 |
| 1451 | Harvard | 5,362 |
| 1608 | Worcester | 5,080 |
| 1612 | Paxton | 5,013 |
| 1505 | Boylston | 4,855 |
| 1585 | West Brookfield | 4,841 |
| 1005 | Barre | 4,837 |
| 1535 | North Brookfield | 4,750 |
| 1560 | South Grafton | 4,734 |
| 1452 | Hubbardston | 4,338 |
| 1468 | Templeton | 4,009 |
| 1436 | Baldwinville | 3,694 |
| 1503 | Berlin | 3,514 |
| 1541 | Princeton | 3,497 |
| 1506 | Brookfield | 3,443 |
| 1529 | Millville | 3,176 |
| 1518 | Fiskdale | 3,047 |
| 1522 | Jefferson | 2,890 |
| 1542 | Rochdale | 2,815 |
| 1083 | Warren | 2,539 |
| 1611 | Cherry Valley | 2,188 |
| 1515 | East Brookfield | 2,120 |
| 1537 | North Oxford | 1,935 |
| 1434 | Devens | 1,763 |
| 1031 | Gilbertville | 1,697 |
| 1068 | Oakham | 1,585 |
| 1368 | Royalston | 1,455 |
| 1092 | West Warren | 1,428 |
| 1366 | Petersham | 1,177 |
| 1531 | New Braintree | 984 |
| 1074 | South Barre | 694 |
| 1037 | Hardwick | 582 |
| 1745 | Fayville | 554 |
| 1438 | East Templeton | 385 |
| 1094 | Wheelwright | 44 |
| 1525 | Linwood | 31 |
| 1561 | South Lancaster | 0 |
The data shown reflect ZCTAs from the US Census. As of 2024, there are 85 ZCTAs in Worcester County, Massachusetts (US Census).