Bedrift O - Skedsmokorset
- Olinco AS
- Osn AS
- Orkestra AS
- Onemed AS
- Oleka AS
- Onninen AS
- Oddis Holding AS
- Oddveig Gundersen
- Outlet Scandinavia AS
- Osprey Event AS
- Odinvangen Huseierforening
- Olsen Steinar
- Odinvangen Huseierforening
- Oslo Bowlingskole
- Osprey Event AS
- Office Garden AS
- Obv Drift AS
- Oslo Vedhandel AS
- Ola Wærhaug
- Olav Amundsen
- Olivia Hansson
- Oslo Fotograflaug
- Optikk 2020 AS
- Otto Olsen AS
- Ovidijus Bladzinauskis
- Onir Holding AS
- Obrovac Linda
- Oslo Kranbilservice AS
- OneMed Services AS
- Office Riga
- Oslo Auto Express AS
- Oslo Christian Assembly
- Osteopat Jansen Hasle
- Oslo Christian Assembly
- Oslo Bilhjelp Holding AS
- Office Garden Holding AS
- Ole Kristian Ruud
- Origo-DA Sigmund Danielsen
- Oslo Blaaseorkester SA
- Opp Av Sjøen AS
- Ojr Rydland Holding AS
- Otto Olsen Holding AS
- Otto Olsen Invest AS
- On Beach Invest AS
- Ordo Aqua Vitae
- Otto Olsen AS Avd Produksjon
- Oppover Bjørn Skovli
- Oskars Bartkevics Montasje
- Oiltalk Vegard Hasselberg
- O.B.Wiik AS
- O.B. Wiik A/S
- Omnfoto Ole Martin Nilsen
- On Our Own Productions AS
- Oslo og Omegn Modellhelikopterklubb
- Oslo Bud & Vare AS
- Olsbakk Anleggsservice Kim Olsbakk
- O.B.Wiik Covers AS
- O.B.Wiik International AS
- O.B.Wiik Services AS
- O.B.Wiik Utleie AS
- O.B.Wiik Hall AS
- Oslo Kjøl & Klima AS
- Organisasjon for Narvik-Tamiler
- O.B. Wiik A/S Avd Salg
- O.B. Wiik A/S Avd Utleie
- Open Top Sightseeing Norway AS
- Oslo Drift og Vedlikehold AS
- Oldtimer Service Bjarne Koren
- Oslo Bilhjelp Hans-Erik Gaarder
- O.B.Wiik Tech Textiles AS
- Olsens Hus og Hytte Service