Bedrift O - Hosle
- Opinionspartiet
- Opinionspartiet
- Oeconomica DA
- Overskudd AS
- Opnii AS
- Okeanos AS
- Olsrud Media
- Oda Riis
- Opptun Boligsameie
- Opptun Boligsameie
- Oslo Reklamebyrå AS
- Oliven Eiendom AS
- Ophelia Invest AS
- Oev Consulting AS
- Orkan Holding AS
- Overskudd Opplæring AS
- Osm Fredenlund AS
- Oslo Lyskilder AS
- Oslo Reklamebyrå AS
- Oslo Bowling Krets
- Oslo Amatørastronomers Forening
- Okior Noride Marvin
- Omni Retail Holding AS
- Organized Creative Business Ltd
- Opus Tre Gunnar Homstvedt
- Oslo Bygg Martin Mazurek
- Osteopati Forskning og Informasjon Christian Fossum