Bedrift O - Hagan
- Onlog AS
- Orientdeli AS
- Odinteq AS
- Onhold AS
- Optipos AS
- Oslofinér AS
- Otto Schwensen
- Ottestad-Hansen
- Olszynska Renhold
- Orkide Sandsmark
- Omholt Vaktmesterservice
- Oslo Bilglass AS
- Oslo Kø
- Olszynska Renhold
- Oplandske Spritfabrik ANS
- Omar Service
- Oso Holding AS
- On-Ramp AS
- Oxygen Furniture AS
- Overn Holding AS
- On Road AS
- Otto Olsen AS
- October Consulting AS
- Ovit Consulting AS
- Omega Norge AS
- Oslo Trykkluft AS
- Odd Terje Bjarkøy
- Oslo Barn Hunt
- Oj Sagen Konsult
- Oslo Transport Khan
- Oslo Barn Hunt
- Oslo Trykkluft Holding AS
- Onkel Skrue Kapital AS
- Oslo Finerfabrikk Holding AS
- Oslo Akershus Brytekrets
- Oy Wilfa Suomi AB
- Oslo Krav Maga Klubb
- Olsen Truls H H
- Olympia Bygg Christos Karalis
- Oslo Termografi og ByggTeknikk
- Oslo & Viken Rørlegger AS
- Oslo Termografi og Byggteknikk AS
- Og Vedlikeholdsservice Romerike Renhold
- Ole Brums B.i.L
- Optimal Bygg & Eiendom AS Johnny Enger
- Ola-Pers ved Kjell Olav Hemstad