- Maple Valley Heights
- Maplewood Heights
- Mar A Villa Mobile Home Park
- Marsh Island
- Maury
- Maury Island
- May Creek
- May Valley Manor Mobile Home Park
- Maywood
- McGilvara
- McMicken Heights
- McVan
- Mercer Heights
- Mercer Island Town
- Meredith
- Meridian
- Metum
- Midlakes
- Midway
- Mileta
- Miller River
- Mint Grove
- Mirrormount Estates
- Misty Mountain Mobile Home Park
- Moorland
- Moorlands
- Morganville
- Morningside
- Mount Si Mobile Home Park
- Mount View