Bedrift O - Melhus
- Ovdin AS
- Oppstu Samdrift DA
- Oppigard Arbeidssenter
- Osloveien 18b AS
- Opøien Consult
- Onsøyen Øyvind
- Oddbjørn Sandvik
- Olav Skarsem
- Ojn Holding AS
- O. Øye AS
- Oliver-Holding AS
- Ottestad Vilde
- Ove Tokstad
- Orixs Grøtan
- Opland Maskin AS
- Olastubakken Sameie
- Opland Lars
- Olav Haugen Taxi
- Odd Inge Samdal
- Ole Morten Øyås
- O. Øye Holding AS
- Ola Sandrød Holding AS
- Om Hansen Holding AS
- Ole Mathias Klomstad
- Ole Asbjørn Hjulstad
- Olderøien Jon Atle
- Olden Total Fix.
- Oslo Hundeskole - Trondheim
- Ola Nordhammer Holding AS
- Oris Dental Melhus
- Orkla Lax Hasse Dehlin