Bedrift O - Tonsenhagen
- Osike AS
- Olena Ivakhenko
- Oak Mtach AS
- O&M Holding AS
- Onething Europe
- Onething Europe
- Olsenssnekkerservice Morten Olsen
- Obsye Ibrahim Mohamed
- Oslo & Viken Renhold AS
- Oslo & Viken Bygg AS Konkursbo
- Oslo & Viken Bygg AS Konkursbo
- Oversetting og Litteraturformidling Maaike Lahaise
- Oslo Bygg Per Johan Ensio Wising