19 cities
| City | County | 2025 Pop. ↓ |
|---|---|---|
| Lowell | Middlesex County | 121,683 |
| Lynn | Essex County | 105,110 |
| Lawrence | Essex County | 89,915 |
| Leominster | Worcester County | 44,510 |
| Lexington | Middlesex County | 35,190 |
| Ludlow | Hampden County | 21,328 |
| Longmeadow | Hampden County | 15,754 |
| Lynnfield | Essex County | 13,347 |
| Lakeville | Plymouth County | 12,416 |
| Lunenburg | Worcester County | 12,087 |
| Leicester | Worcester County | 11,313 |
| Littleton | Middlesex County | 10,634 |
| Lancaster | Worcester County | 9,136 |
| Lincoln | Middlesex County | 7,047 |
| Lee | Berkshire County | 5,663 |
| Lenox | Berkshire County | 5,072 |
| Lanesborough | Berkshire County | 2,999 |
| Leverett | Franklin County | 1,861 |
| Leyden | Franklin County | 738 |