Firma O - Skedsmokorset
- Olinco AS
- Orkestra AS
- Oleka AS
- Osn AS
- Onninen AS
- Onemed AS
- Ola Einbu
- Osprey Event AS
- Odinvangen Huseierforening
- Oslo Vedhandel AS
- Osprey Event AS
- Olsen Steinar
- Office Garden AS
- Oddis Holding AS
- Opsen Holding AS
- Oslo Bowlingskole
- Odinvangen Huseierforening
- Oddveig Gundersen
- Outlet Scandinavia AS
- Olsen Erik
- Ola Wærhaug
- Obrovac Linda
- Olivia Hansson
- OneMed Services AS
- Olsen Harald
- Olav Amundsen
- Oskars Bartkevics
- Olsen Einar
- Okbay Beyene
- Onir Holding AS
- Optikk 2020 AS
- Otto Olsen AS
- Office Riga
- Osteopat Jansen Hasle
- Ole Petter Friberg
- Office Garden Jessheim AS
- Office Garden Holding AS
- Oslo Bilhjelp Holding AS
- Oslo Auto Express AS
- Oppover Bjørn Skovli
- Otto Olsen Holding AS
- Origo-DA Sigmund Danielsen
- Ole M. Almeli AS
- Ole M. Almeli AS
- Otto Olsen AS Avd Produksjon
- Ojr Rydland Holding AS
- Otto Olsen Invest AS
- Ordo Aqua Vitae
- Ole Kristian Ruud
- Opp Av Sjøen AS
- Oiltalk Vegard Hasselberg
- Ole Victor Corral
- On Beach Invest AS
- O.B.Wiik AS
- Omnfoto Ole Martin Nilsen
- Oslo og Omegn Modellhelikopterklubb
- On Our Own Productions AS
- O.B. Wiik A/S Avd Utleie
- Organisasjon for Narvik-Tamiler
- Oslo Drift og Vedlikehold AS
- Open Top Sightseeing Norway AS
- O.B.Wiik Utleie AS
- O.B. Wiik A/S Avd Salg
- Olsbakk Anleggsservice Kim Olsbakk
- Oslo Kjøl & Klima AS
- Oslo Bilhjelp Hans-Erik Gaarder
- Opplæringskontoret for Service og Samferdsel SA
- Opplæringskontoret for Tele, Data og Elektro