Bedrift O - Ullern
- Oktober AS
- Oncosyne AS
- Olto AS
- Opheims AS
- Otnortopco AS
- Odibalol
- Optia AS
- Oppvekst AS
- Oradell AS
- Osloco AS
- Oryx AS
- Obirk AS
- Ohm AS
- Oljemegleren AS
- Otern AS
- Oleksandr Kononiuk
- Onsøy Holding AS
- Oslo Lydservice AS
- Orion Alemayohu
- Oda-Nettverk
- Oda-Nettverk
- Onkologisk Forum
- O. Blyskavka
- Olsen Kine
- Omland Consulting
- Olav Røst
- Oslo Byforum
- Ottesen Fredrik
- Oksana Kramerenko
- Olena Palaznik
- Oleksii Pidrepnyi
- Ogs Holding AS
- Ogs Seed AS
- Olafsens Investering
- Oi-Holding AS
- Oslo Tobakkfabrikk AS
- Oslo Taco AS
- Oaulina Sobczak
- Opptur Helse AS
- Oddvar Stenstrøm
- Oma Kaiku AS
- Otto To AS
- Ort Invest AS
- Oslo Sykleklubb
- Oslo Sykleklubb
- Ohm Elin
- Ortho Vita AS
- Oksehoved Holding AS
- Olav Landsverk
- Olsen Re:Nu:Sign
- Oslo Folkeakademi
- Oslo Ryttersportsklubb
- Ohrian Records Nordtorp
- Oversetter Marianne Staveland
- Osmani Venture Capital AS
- O2 Agency Solutions AS
- Olabode Babatunde Awuyo
- Oslo Cancer Cluster
- OK Minilager Ullern
- Oslo Kuksoolwon Klubb
- Oslo Malerservice Giannis
- Ole-Petter Svarstad
- Olafsen John Arild
- Ohg-Revyen 2018
- Oj Assistanse Oldertrøen
- Olagarden Furseth Overnatting
- Oslo vest Parkinsonforening
- Omega Bolig Eiendom AS
- Ohg-Revyen 2018
- Oslo Chauffeur Service AS
- Oslo Geofysikeres Forening
- Osloconnection Omar Rashid
- Otterstad Per Christoffer Øian
- Oslo N.K.S
- Oslo Cancer Cluster Incubator AS
- Oslo Universitetssykehus HF Radiumhospitalet - Forskningsvirk
- Olaf Weisser Offshore Consulting
- Oslo Universitetssykehus HF Radiumhospitalet - Adm/Fellestjen
- Oslo Universitetssykehus HF Radiumhospitalet - Lab/Røntgen
- Ole Morten Skogheim Invest AS
- Ole Martin Bakkevold Foto
- Oppeboenconsulting Kjell Arne Oppebøen
- Offa Consult Terje Jacobsen
- On Own Feet - Tusenbenets Venner
- Olga Løfshus Spes.Sykepl.Opr/Anestesi
- Oslo Kvinnelige Handelsstands Forenings Stiftelse
- Oslo Kvinnelige Handelsstands Forenings Stiftelse
- Oslo Total Elektro Florian-Robert Barbu