Bedrift O - Drøbak
- Optipharma AS
- Olram AS
- Oppdragskontakt
- Opplyst AS
- Optitec DA
- Oxitrate AS
- Omsorgsenglene
- Omsorgsenglene
- Off Season AS
- Oslofjorden Kunstsenter
- Ovidia Bay
- OSL 37 AS
- Opticell Norge AS
- Oda Tømte
- Overskott Eiendom AS
- Og Eiendom AS
- Omloks Holding AS
- Oscarsborg Invest AS
- Olsrud Agentur
- Oval Kapital AS
- Oscarsborg Festningsforening BA
- Oscarsborg Pistolklubb
- Oliv Halvorseth
- Okkenhaug Prosjekt
- Orebjörk Kroppsterapi
- Overgaard Consulting
- Olafssøn Consulting
- Oslo Pumpeservice AS
- Oscarsborg Eiendom AS
- Oscarsborg Gjestehavn AS
- Oscarsborg Festning
- Osloveien 20 AS
- Orso Vero AS
- Oslofjord Pianofestival
- Odd Lautin
- Olav Gislerud
- Oreveien Vel
- On-Time
- Orning Consulting
- Olivenlund Invest AS
- Olive Nyiranziza
- One Truth AS
- Oslofjord Utvikling AS
- OK Glass AS
- Ottarsrud Henning
- Ombudstvedt Andreas
- Oslo Håndballklubb
- Oddrun Bøhlerengen
- Odalsparken Velforening
- Odalsparken Velforening
- Ofstad Conflict Management
- Off Grid Energy AS
- Oslo Blikkenslager Service AS
- Oscarsborg Gjestehavn Servering AS
- Oscarsborg Festnings Venner
- Oda Bhar Lurås
- Oppussing Marek Rumin
- Osteopat Liselotte Lund
- Oslofjorden Båteierunion - Obu
- Opaker Pilskog Consulting
- Oslofjorden Kulturråd, Forening
- Oslo-Follo Flytteservice
- Ole Brumm Familiebarnehage
- Ole Jørgen Grumstad
- Opc Asset Holdings AS
- Opc Integrated Services AS
- Optimaliser Milad Moradi
- Ocean Wind Services AS
- Ofelia Of Norway AS
- Oh Slåke Holding AS
- Ole Martin Tomter
- Oslofjord Consulting Kristian Fæste
- Oscarsborg Hotel & Resort
- O H Slåke Invest AS
- Oslofjordtjenester Rune Kermit Røsrud
- Olsen Financial Consulting & Services
- Ove Arnesen Anlegg og Transport
- Oscarsborg Event S Rønning Consult
- Oslo Latvisk Teater O Latte
- Odv Bygg og Eiendom Niklas Olsen
- Orphan Norway Norsk Filial Av Utenlandsk Foretak