Firma O - Furuset
- Octopus AS
- Optimove AS
- Oterra
- Orogenic AS
- Oti AS
- Oleskiy Cherepukhin
- Oppsiden Eiendom AS
- Osman Sebaydin
- Oslo Sawari
- Odin Entreprenørfirma AS
- Oslo Workwear AS
- Ok Soldrift AS
- Ok Eiendom AS
- Olsen Rune
- Oslo Unilabs
- Olavesen & Co Eiendomsforvaltning
- Oslo Cab AS
- Oslo Snekkere AS
- Oslo Fryselager AS
- Oleg Sveiseverksted
- Oslo Elektrikere AS
- Oslo Lagerhotell AS
- Oslo Sanitetslag Alarmtelefon
- Oslo Rock Service AS
- Oslo Vakt Snø
- Oz Kvalitet Mehmed
- Odyn Odd Steinsmoen
- Oslo Antigraffiti Team ANS
- Olaf Johansens Eftf. AS
- O Kristoffersen Bingodrift AS
- Oslo Total Oppussing
- Oslo Bygg Teknikk AS
- OK Bingo Arkaden
- Oslo Bygg Teknikk AS
- Oslo VVS Senter AS
- Oslo Sweets & Bakers AS
- Oslo Alna Rotary Klubb
- 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 Bud & Vare AS
- Oslo City F.C.
- Oslo City F.C.
- Oslo Bud O Ren AS
- Oromisk Muslimsk Samfunn i Norge
- Ohana for Barn og Unge
- Ohana for Barn og Unge
- Oslo Audio & Video Service AS