| Nordlie AS | Real estate | 1964 |
| Nordlyset Transport Bygg & Rengjøring AS | Transport & logistics | 2024 |
| Nordlysveien 6 AS | Real estate | 2024 |
| Nordtex AS | Manufacturing | 2020 |
| Nordtømme Management Consulting AS | Professional & scientific | 2001 |
| Nore Eiendomsutvikling AS | Real estate | 2008 |
| Nore ST Holding AS | Real estate | 2018 |
| Norgesgym AS | Arts & recreation | 2010 |
| Norheim Eiendom AS | Real estate | 2001 |
| Norlab AI AS | Information & communication | 2023 |
| Norman Holding AS | | 2019 |
| Norpluss Consult AS | Professional & scientific | 1992 |
| Norscan AS | Wholesale & retail | 2004 |
| Norscan Eiendom AS | Real estate | 2013 |
| Norscan Næringseiendom AS | Real estate | 2013 |
| Norscan Racing AS | Arts & recreation | 2021 |
| Norsk Betongmontasje AS | Construction | 2008 |
| Norsk Bygg Sikring AS | Construction | 1998 |
| Norsk Båt-Taksering AS | Professional & scientific | 2025 |
| Norsk Data Lagring AS | Information & communication | 1998 |
| Norsk Eiendomstakst AS | Real estate | 2022 |
| Norsk Meglerkompetanse AS | Real estate | 2005 |
| Norsk Reiselivsrådgivning AS | Professional & scientific | 2005 |
| Norsk Rør & Tank Isolering AS | Construction | 2023 |
| Norsk Varesalg AS | Wholesale & retail | 2013 |
| Norskand Prosjekt AS | Professional & scientific | 2013 |
| Nortelco Invest AS | Professional & scientific | 1989 |
| North East Bil AS | Wholesale & retail | 2019 |
| North Sun AS | Construction | 2025 |
| Nortools AS | Wholesale & retail | 1994 |
| Norwa Ltd Nuf | Administrative & support | 2017 |
| Norwaytwins AS | Arts & recreation | 2023 |
| Norwegian Energy Holding AS | Real estate | 2008 |
| Norwegian Idea AS | Real estate | 2007 |
| Norwegian Tools AS | Wholesale & retail | 1990 |
| Nos AS | Construction | 2016 |
| NOTA4 AS | Health & social care | 2004 |
| Noteka Invest AS | Real estate | 1985 |
| Novus Via 2 AS | Professional & scientific | 2026 |
| Novus Via AS | | 2019 |
| Nsø Holding AS | Financial services | 2018 |
| Nudler Holding AS | | 2026 |
| Nuovo Skin & Mind - Inga Fjæran AS | Other services | 2023 |
| Nurholding AS | | 2026 |
| Nustad Rekruttering AS | Administrative & support | 2021 |
| Nutritionlab AS | Professional & scientific | 2016 |
| Nye FFS Felles Holding AS | | 2024 |
| Nye KG AS | Real estate | 2024 |
| Nye Mosses AS | Hospitality | 2017 |
| Nye Rompuben AS | Hospitality | 2019 |
| Nyhuus Data Da | Wholesale & retail | 2002 |
| Nustad & Partners AS | Professional & scientific | 1986 |
| Nøkleby Holding AS | Information & communication | 2022 |
| Nü by Staff-Woman Nuf | Wholesale & retail | 2010 |
| O Hansen Holding AS | Real estate | 2021 |
| Oberg & Co Arbeidsstylter Ans | Wholesale & retail | 1992 |
| Occivin AS | Wholesale & retail | 2018 |
| Odd Bakke Holding AS | Financial services | 2005 |
| Odd Invest AS | Professional & scientific | 2017 |
| Oddis Vaktmestertjenester AS | Administrative & support | 2023 |
| Oh Ventures AS | | 2025 |
| Oie Holding AS | | 2015 |
| Oikaze AS | Wholesale & retail | 2024 |
| Okk Eiendom AS | Real estate | 2023 |
| Okk Holding AS | Real estate | 2023 |
| Okk Invest AS | Real estate | 2017 |
| Olivia Forlag AS | Information & communication | 2020 |
| Olsen Solutions AS | Professional & scientific | 2023 |
| Omega Tek AS | Wholesale & retail | 2018 |
| Omre & Johansen Eiendom Ans | Real estate | 2000 |
| Omrm AS | Information & communication | 2016 |
| Omsorgsgruppen AS | Health & social care | 2021 |
| Omstilling AS | Professional & scientific | 2000 |
| Onna Greens AS | Agriculture & fishing | 2016 |
| Onsøy Holding AS | Real estate | 2010 |
| Opem Pulverlakkering AS | Manufacturing | 2017 |
| Opendigital AS | Information & communication | 2025 |
| Ophd Holding AS | Information & communication | 2023 |
| Opplæringsbedriften AS | Education | 2023 |
| Optimal Prestasjon AS | Arts & recreation | 2014 |
| Ordspill AS | Information & communication | 2026 |
| Orix AS | Information & communication | 2025 |
| Oslo Hybelutleie AS | Real estate | 2011 |
| Oslo Og Follo Vedlikeholdsservice AS | Construction | 2012 |
| Osloveien 140 AS | Real estate | 2013 |
| Osloveien 142 AS | Real estate | 2016 |
| Osloveien 149 AS | Real estate | 1998 |
| Osloveien 161 a AS | Real estate | 2016 |
| Osloveien 323B AS | Real estate | 2017 |
| Osloveien 366 AS | Real estate | 2022 |
| Osloveien 46/48 AS | Real estate | 2007 |
| Osloveien 80 AS | Wholesale & retail | 1967 |
| Ovantis AS | Financial services | 2013 |
| Onstad Eiendom og Invest A/S | Real estate | 1963 |
| P-Consult AS | Wholesale & retail | 1998 |
| P7 Invest AS | Real estate | 2005 |
| P7 Legesenter AS | Health & social care | 2015 |
| Paasche Holding AS | | 2005 |
| Padelbaner AS | Arts & recreation | 2017 |
| Palex Invest AS | | 2021 |