Bedrift O - Tananger
- Oblomov AS
- Orsem AS
- Okktav AS
- Oldtimers AS
- Oljegutta AS
- Oh&HH AS
- Odfjell Drilling AS
- Orgelbyggeri Wirpi
- Ole - Bjergsted
- Offshore Partners AS
- Operation Clambake
- Oleh Koronenko
- Ovenpaa Velvaere AS
- Om Tekstiltrykk AS
- Orjank Invest AS
- Offshore Partners AS
- Oleksandr Lahno
- Oslo Taxi AS
- Ove Myklebust
- Ove Roksvåg
- Odd Løgith Svendsen
- Ole Johan Mæland
- Ob Myklebust Undervisning
- Osono Dance Company
- Olena Sitnova-Osadcha
- Ors Rental Equipment AS
- Odfjell Engineering AS Avd Tananger
- O P Thingbø AS
- Oeg Offshore Holding AS
- Onsite Treatment Services AS
- Odfjell Well Services
- Ognedal Maritime Services AS
- Orasinski Guiding og Fotografi
- Os Antikk og Brukt
- Oil Spill Response (Swis) Norway AS
- Oljas Kake Boutique Olga Tønnessen
- Oil Spill Response (Swis) Norway AS
- One Take Only Studios Jan Ove Ottesen