| City | County | 2026 Pop. ↓ |
|---|---|---|
| Boston | Suffolk County | 671,635 |
| Brockton | Plymouth County | 106,078 |
| Brookline | Norfolk County | 63,421 |
| Barnstable Town | Barnstable County | 50,134 |
| Beverly | Essex County | 43,450 |
| Billerica | Middlesex County | 42,616 |
| Braintree Town | Norfolk County | 39,073 |
| Bridgewater Town | Plymouth County | 29,267 |
| Belmont | Middlesex County | 27,013 |
| Burlington | Middlesex County | 26,762 |
| Bourne | Barnstable County | 20,759 |
| Bellingham | Norfolk County | 18,201 |
| Belchertown | Hampshire County | 15,258 |
| Bedford | Middlesex County | 14,835 |
| Brewster | Barnstable County | 10,411 |
| Blackstone | Worcester County | 9,450 |
| Boxford | Essex County | 8,691 |
| Bolton | Worcester County | 7,150 |
| Berkley | Bristol County | 6,991 |
| Barre | Worcester County | 5,652 |
| Boxborough | Middlesex County | 5,492 |
| Boylston | Worcester County | 5,140 |
| Brimfield | Hampden County | 3,750 |
| Brookfield | Worcester County | 3,529 |
| Berlin | Worcester County | 3,489 |
| Bernardston | Franklin County | 2,102 |
| Becket | Berkshire County | 1,912 |
| Buckland | Franklin County | 1,808 |
| Blandford | Hampden County | 1,214 |