Bedrift O - Smestad
- Ormaz AS
- Ormaz AS
- Opponens AS
- Overdrive AS
- Ossau AS
- Oakenhurst AS
- Olim Svømmeundervisning
- Oversand Gynekolog
- Odin Eide
- Oslo Tangoverksted
- Orakel Strategy AS
- Observatoriet Holding AS
- Observatoriet Invest AS
- Oslo Sanitetsforening
- Oppover Bakke
- Otto Jespersen
- O-Eiendom AS
- Oluwabykola Adeniyi
- Ojh-Holding AS
- Oslo Ideation AS
- Optimal Link AS
- Owe Holding AS
- Optimal Trener AS
- Otto Haug AS
- Ok Helse AS
- Oxen Invest AS
- Optimal Klinikk AS
- Oslo Sanitetsforening
- O-Eiendomsutvikling AS
- Oslo Naprapatklinikk
- Olav Orud
- Otterbeck Communication
- Ohme Design
- Ovenberg Productions
- Ola Johansen
- Olav Wæthing
- Oslo Frakt AS
- Ola Eriksrud AS
- Oso Consulting AS
- Open House Oslo
- Oversetter Martin Solholm
- Outi-Kristiina Elomeri
- Odins gate 16 AS
- Ocean Partners Association
- O. Væring Eftf AS
- Ole Gustav Stenhagen
- Ocean Partners Association
- Olga Abo Obaid
- Oslo Sanitetsforening Eiendom AS
- Oslo Sanitetsforening Forvaltning AS
- Oslo Jazz Circle
- Oppussing Kompaniet AS Tvangsavviklingsbo
- Oppussing Kompaniet AS Tvangsavviklingsbo
- Ott Takst og Eiendom AS
- Oscar Wistings vei Panorama AS
- Odins gate 16 Holding AS
- Oslo Universitetssykehus HF Ambulansetjenester Smedstad
- Oslo Røde Kors vestre
- Oslo Sanitetsforening Venners Fond
- Oslo Oppussing AL Ali Ekspert
- Olå Kvinnehelse Oskar L Åkesson
- Olinfo Consult Olav Inge Fossbakken
- One Bucket Production S Påhlsson
- Organisasjonen for veien til Finansiell Frihet
- Organisasjonen for veien til Finansiell Frihet
- Oslo Welsh Society- Cymdeithas Cymry Oslo
- Overrettssakfører Axel Dahl og Hustru Karethe Kittilsen Dahls
- Overrettssakfører Axel Dahl og Hustru Karethe Kittilsen Dahls Legat
- Oslo Sanitetsforening Fond til Beste for Barn og Ungdom