- Macedonia
- Madison
- Madison Center
- Major Island
- Manchester
- Manchester Green
- Manitock Spring
- Manresa Island
- Mansfield Center
- Mansfield City
- Mansfield Depot
- Mansfield Four Corners
- Mansfield Hollow
- Marble Dale
- Margerie Manor
- Marine Island
- Marion
- Marlborough
- Maromas
- Marvin Island
- Mary Rock
- Mashantucket
- Mashapaug
- Mason Island
- Massapeag
- Mayberry Village
- McClaveville
- Meadowbrook
- Meadowgate
- Mechanicsville