| Novela Outdoor AS | Financial services | 2017 |
| Novela Teknologi AS | Financial services | 2016 |
| Nowaco Norway Nuf | Wholesale & retail | 2015 |
| NSB Holding AS | | 2021 |
| NSG41 AS | Real estate | 2023 |
| NSM AS | Real estate | 2005 |
| NSS AS | Other services | 2023 |
| Nss-Group AS | Real estate | 2022 |
| Nss-Group Eiendom AS | Real estate | 2022 |
| NT Invest AS | | 2025 |
| Ntnu Ocean Training AS | Education | 2011 |
| Numero Consultants AS | Professional & scientific | 1997 |
| Numero Partners AS | Professional & scientific | 2005 |
| Nummer 16 AS | Real estate | 2023 |
| Nurk AS | | 2025 |
| Nuvu AS | Manufacturing | 2020 |
| NVR Holding AS | | 2008 |
| Nxmh AS | Manufacturing | 2013 |
| Ny Bolig Ålesund AS | Construction | 2017 |
| Nyasa Consulting AS | Professional & scientific | 2021 |
| Nybø Invest AS | | 2022 |
| Nybø Maling Og Bygg AS | Construction | 2022 |
| Nye Aalesund Enterprises AS | | 2025 |
| Nye Ask Safety Holding AS | | 2025 |
| Nye Caro AS | Wholesale & retail | 2026 |
| Nye Eisø AS | Hospitality | 2023 |
| Nye Icefresh AS | | 2022 |
| Nye Norgesstillas AS | Administrative & support | 2026 |
| Nyport AS | Information & communication | 2021 |
| Nærbygg AS | Construction | 2009 |
| Nødingen AS | Hospitality | 2005 |
| Nørve Drift AS | Hospitality | 2023 |
| Nørve Eiendom AS | Real estate | 2006 |
| Nørve's Automobilservice AS | Other services | 2024 |
| Nørvebana AS | Real estate | 2014 |
| Nørvegata Frisør Og Solarium Ans | Other services | 1993 |
| Nørvevika AS | Real estate | 2006 |
| O Klokkehaugs Eftf Ans | Manufacturing | 1997 |
| O. B. Solvang Agentur AS | Wholesale & retail | 2009 |
| O. Grebstad AS | Real estate | 2007 |
| O. J Lyng Invest AS | Financial services | 2011 |
| O.E.Hauge Eiendom AS | Real estate | 2006 |
| O.Løken Holding AS | Financial services | 2008 |
| Oa Aarseth AS | Professional & scientific | 2022 |
| Oasen Interiør AS | Professional & scientific | 2024 |
| Ob Invest AS | Real estate | 2010 |
| Obos Nordvest Utbygging AS | Real estate | 1986 |
| Obratech AS | Information & communication | 2025 |
| Obs-Systemer AS | Professional & scientific | 1988 |
| Obw Holding AS | Other services | 2005 |
| Ocean Cleaner AS | | 2018 |
| Ocean Hill AS | Administrative & support | 2020 |
| Ocean Hull Cleaning AS | Administrative & support | 2025 |
| Ocean Industries AS | Information & communication | 2020 |
| Ocean Rally AS | Administrative & support | 2024 |
| Ocean Risk & Reward AS | Financial services | 2023 |
| Ocean Solution AS | Administrative & support | 2022 |
| Ocean Supreme AS | Wholesale & retail | 2003 |
| Ocean Supreme Holding AS | Wholesale & retail | 2020 |
| Oceanblock AS | Agriculture & fishing | 2026 |
| Oceanfjord AS | Professional & scientific | 2009 |
| Oceantherm AS | Professional & scientific | 2024 |
| Oceanvju AS | Professional & scientific | 2025 |
| Octopus Invest AS | Agriculture & fishing | 2005 |
| Oculus AS | Health & social care | 1996 |
| Odd Jarle Døving Bedriftsrådgivning AS | Professional & scientific | 2015 |
| Odd-Invest AS | Construction | 2012 |
| Oddbjørn Hatløy Holding AS | | 2022 |
| Oddvar Vatnehol Holding AS | Financial services | 2005 |
| Ode AS | Agriculture & fishing | 2020 |
| Ode Brands AS | Wholesale & retail | 2025 |
| Ode Eiendom Stadsbygd AS | Real estate | 2023 |
| Ode Holding AS | Agriculture & fishing | 2019 |
| Odin Eiendom AS | Real estate | 1992 |
| Odla Holding AS | Manufacturing | 2024 |
| Oec Invest AS | Financial services | 2024 |
| Oems AS | Financial services | 2017 |
| Oeng Invest AS | | 2020 |
| Oero Invest AS | Financial services | 2017 |
| Office Spaces AS | Real estate | 2021 |
| Offshore & Industriprodukt AS | Manufacturing | 1993 |
| Offshore Wind Investor AS | Transport & logistics | 2023 |
| Ohh Invest AS | | 2024 |
| Oilcraft AS | Professional & scientific | 2013 |
| Oj Myklebust Holding AS | | 2026 |
| Oj Østrem Invest AS | Financial services | 2017 |
| Oj-F Holding AS | | 2025 |
| Ojma Holding AS | Financial services | 2017 |
| Ok Capital AS | | 2017 |
| Ok Entreprenør AS | Construction | 2010 |
| Ok Entreprenør Eiendom AS | Real estate | 2023 |
| Oka Invest AS | | 2018 |
| Okbygg AS | Construction | 2019 |
| Oksnes Services & Motordeler AS | Wholesale & retail | 1996 |
| Ola Pedersen Invest AS | | 2023 |
| Ola Volstad Holding AS | Transport & logistics | 1994 |
| Olavsgata 8 AS | Real estate | 2020 |
| Ole Edvardsen Holding AS | Financial services | 2005 |
| Olestro AS | | 2025 |
| Olibor AS | Real estate | 2005 |