- Oak Grove (Population: 6,903)
- Oak Park Heights (Population: 3,957)
- Oakdale (Population: 26,653)
- Oakport (Population: 1,334)
- Olivia (Population: 2,570)
- Orono (Population: 7,538)
- Ortonville (Population: 2,158)
- Osakis (Population: 1,567)
- Osseo (Population: 2,434)
- Otsego (Population: 6,389)
- Owatonna (Population: 22,434)
