- Old Victoria Historic Townsite
- Oldport
- Olive Center
- Olivers
- Ollies Dogs Rocks
- Olney Corners
- Olson
- Omena
- Oneida Center
- Onekama Junction
- Onondaga
- Onota
- Ontario Place Mobile Home Park
- Orangeville
- Orangeville Island
- Orchard
- Orchard Beach
- Orchard Cove Manufactured Home Community
- Orchard Grove Village Mobile Home Park
- Orchard Park
- Orchard Point
- Orchard View Estates
- Orion Rock
- Orleans
- Orono
- Orr
- Osceola
- Oscoda Mobile Home Park
- Oshtemo
- Oskar