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