Bedrift O - Son
- Oform AS
- Oninvest AS
- Oxovi AS
- Opplæringssenteret AS
- Optidev AS
- Oxyvision AS
- One Take AS
- Ola Fløttum
- Olsens Multimedia
- Otterstadh Vaktmestertjenester
- Oppegårdjentene 2021
- Oplandske Bokforlag AS
- Oppegårdjentene 2021
- Olsen Media
- Oslofjord Info
- Oles Smedforretning
- Overgaard-Manpower
- Oles Smedforretning
- Oe Kanestrøm Consulting AS
- Oxyvision Holding AS Avd Son
- One Solution Group AS
- Oslo Kfum Leirstedet Lunde
- Oslo Skiltmaler Richard Chlaszczak
- Outdoor Wellbeing Åsa Maria Lagerstedt
- Oppgrader Ditt Liv Rita M Sund
- Oughten House Publications Europe AB V/Byrået i Son