Bedrift O - Skarpsno
- Orgservice
- Orbono AS
- Orgproff AS
- Orhaug Da
- Odipadi AS
- Occasion AS
- Olymp AS
- Occasion AS
- Oculos AS
- Olga Dyubina
- Oslo Seniorkor
- O Capital AS
- Off Tek AS
- Olena Kurtius
- Orvei Invest AS
- Omega Bil AS
- Oslo Opportunity AS
- Opplæringskontor AOF
- Oxygen Music AS
- O Rygh AS
- Office R&T AS
- Ovr Holding AS
- Oslo Tannlegeforening
- Oslo Eiendomsutvikling AS
- Osc Technology AS
- Oslo Takstsenter AS
- Otto Holmen AS
- Oh Holding AS
- Ottersen Health
- Orator Team AS
- Oslo Taksthus AS
- Oslofjord kajakk
- Oli Invest AS
- Omd Holding AS
- Oslo Kjøkkenstudio AS
- Olof Nylins Stiftelse
- Ole Bendik Eilertsen
- Olof Nylins Stiftelse
- Oslo Sentrum Holding AS
- Oslo Sentrum Eiendom AS
- Orion Search International AS
- Oslo Opportunity II AS
- Offentlig Bygg Hamar AS
- Orion Search International AS
- Oddvar Kjell Gundersen
- Osteopat Rebekka Riiber
- Ola R Knutsen
- Oslo Global Choir
- Olav Kyrresg 6 AS
- Ola Bjørnsønn Johannessen
- Olaf H. Thommessen
- Olav Morten Kise
- Ouafia Hadaoui Fasting
- Oslo Naturmedisinske Klinikk
- Omd Norway Bedriftsidrettslag
- Omd Norway Bedriftsidrettslag
- One Square Meter AS
- Odd Cappelen Holding AS
- Oslo Stevedore Selskap AS
- Omnicom Media Group AS
- Olsens Move And Create
- Oslo Gælisk Rugby Klubb
- Ola Jon Sinding-Larsen
- Olsen Invest And Intelligence
- O. L. Engen Eiendom AS
- O. L. Engen AS Reserve
- Oskar Braatens gate 11 ANS
- Oslo Bym Foodtruck Forening
- Oivindvogt Øivind A Vogt
- Osnes Ragnar Arkitekt Mnal
- Oskar Braatens gate 11a/B
- Oeenb Lotte Øen Bugge
- Oslo Bym Foodtruck Forening
- Oskar Braatens gate 11a/B
- One To One Architects AS
- Olaf Schous vei 20-24 Borettslag
- Olaf Schous vei 13-27 Borettslag
- Olaf Schous vei 12-18 Borettslag
- Olaf Schous vei 13-27 Borettslag
- Olaf Schous vei 12-18 Borettslag
- Olaf Schous vei 20-24 Borettslag
- Osebergfondet (Gabriel Gustafsons Minnefond til Vern Om Fornminner)
- Osebergfondet (Gabriel Gustafsons Minnefond til Vern Om Fornminner)