Bedrift O - Høvik
- Occasio AS
- Ofiniti AS
- Orixe AS
- Opsiana AS
- Oldhistorisk Forening
- Oslo Sportskyttere
- Oslofjorden Seilklubb
- Olaves Narum
- Ottar Schlytter
- Olsen Barneverntjenester
- Oslomua Lea
- Olav Røyse
- Oddenkollen Regnskapsservice
- Oslofjorden Seilklubb
- Ola Fosnæs
- Onsight Invest AS
- Oddworks II AS
- Oskar Næss AS
- Oftedal Consulting
- Odette Mwiseneza
- Occasione Holding AS
- Ocrg Holding AS
- Oh Consult AS
- Ocomp Medinvestering AS
- Oakside Holding AS
- Oea Eiendomsinvest AS
- Oj Productions AS
- Oslo Trebåtfestival AS
- Oddenskogen Barnehage
- Onkelpetter Petter Kristiansen
- O.H. Alstad
- Osloheart By Gjesdal
- Oslo Energy Forum
- Ole Rasmus Grøtteland
- Ole Mikkel Sjølie
- Ole Kristen Fostad
- Odd-Einar Christophersen
- Oslo Urologiske Klinikk AS
- Oddmar Svein-Erik
- Ole Wiig Holding AS
- Ola Berg Lande
- Oracle User Group Norway
- Oskar Andreas Pask Steen
- Oskarsson Dykk og Undervannsservice
- Odd Arild Haugen Eiendomskonsult
- Oslo Trelast- og Byggevareforening
- Oslo Trelast- og Byggevareforening
- Optimal Tracking Geir Victor Svendsen
- Oakcrays Invest Khalid Hussain Malik
- Oriental Culture And Education Association In Norway