Bedrift O - Furuset
- Octopus AS
- Oterra
- Orogenic AS
- Omari
- Omnicus AS
- Oleh Benedychuk
- Oleskiy Cherepukhin
- Olena Pikunova
- Oppsiden Eiendom AS
- Oleksandr Kizino
- Osman Sebaydin
- Odin Entreprenørfirma AS
- Ok Eiendom AS
- Oslo Nestleder
- Oslo Snekkere AS
- Oslo Workwear AS
- Oleg Sveiseverksted
- Oslo Båtimport AS
- Olsen Rune
- Oslo Unilabs
- Ok Soldrift AS
- Oslo Fryselager AS
- Oslo Båtimport
- Oslo Lagerhotell AS
- Orange Gaming AS
- Oslo Cab AS
- Oslo Sanitetslag Alarmtelefon
- Oslo Rock Service AS
- Oz Kvalitet Mehmed
- OK Bingo Arkaden
- Oslo Bygg Teknikk AS
- Oslo VVS Senter AS
- O Kristoffersen Bingodrift AS
- Olaf Johansens Eftf. AS
- Oslo Antigraffiti Team ANS
- Oslo Alna Rotary Klubb
- Oslo Sweets & Bakers AS
- Omar Mohamed Redouan Ben
- Ofbjp Mahila Morcha Norway
- Oslo Viken Taxi Elaachmiri
- Olaf Johansen Eftf AS Avd Produksjon
- Olaf Johansens Eftf AS Avd VVS
- Oslo City F.C.
- Oslo Bud O Ren AS
- Oslo City F.C.
- Oromisk Muslimsk Samfunn i Norge
- Oslo & Viken Transporttjenester Asrar Ahmed
- Oslo & Viken Bad og Flis AS