Bedrift O - Briskeby
- Océmar AS
- Oyho AS
- Opeks AS
- Overvoll AS
- Oakhill AS
- Orkidespesialisten
- Olan AS
- Oda Lind
- Olav Rørstad
- Oslo Malerklubb
- Oslo Patentkontor AS
- Opedal Vetle
- Octo Capital AS
- Octo Ventures AS
- Ospro Bygg AS
- Oslo Patentkontor AS
- Octava Consulting AS
- Olaf Aagedal
- Ob12 Kapital AS
- Ospro Eiendom AS
- Oslo Malermester AS
- Orr Invest AS
- Odda Invest AS
- Oksabotns Venner
- Oksabotns Venner
- Oslo Imperial AS
- Orskaug Invest AS
- Oslo Kvantemedisinske Senter
- Oslo Darts Team
- Ole Christian Frøseth
- Oscar D Løvdal
- Opal Design Tennfjord
- Odd Syse Productions
- Odd Syse Productions