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