Bedrift O - Vollen
- Ortocare AS
- Oslofjordmuseet
- Orklagaard AS
- Oleniuk Mc4you
- Olav Landsverk
- Olav Stadaas
- Oleksandr Tyminskyi
- Olt Invest AS
- Oss Gruppen AS
- Oslofjorden Dykkersenter AS
- Oslofjord Triatlon
- Oiena Yushckenko
- Optimal Synergies AS
- Odd Solutions AS
- Orlin Holding AS
- Oliver Brusdal Film
- Optimum Marine AS Tvangsavviklingsbo
- Optimum Marine AS Tvangsavviklingsbo
- Ole Jørn Gunnerød
- Otterdal Psykisk Helse
- Oliver Kaos Brusdal
- Once-Upon-A-Time AS
- Oslo Hr & Rekruttering AS
- Oslo Hr & Rekruttering AS
- Oslo og Asker Gartnerforening
- Oslofjord Marine & Fishing Duncan Philip Jones