| Nordiske Dekk AS | Wholesale & retail | 2025 |
| Nordlia Utvikling | Real estate | 2022 |
| Nordmo AS | Real estate | 2007 |
| Nordmo Tomt AS | Real estate | 2021 |
| Nordskogveien AS | Real estate | 2016 |
| Norgesbakeriene Romedal AS | Real estate | 2016 |
| Normina AS | Information & communication | 2023 |
| Norne Investeringsselskap AS | Wholesale & retail | 2005 |
| Norne Partners AS | Professional & scientific | 2026 |
| Norpol Exponts Michal Jagodzinsici | Construction | 2011 |
| Norseman Holding AS | | 2020 |
| Norsol Holding AS | Financial services | 2005 |
| Norvaldtjønnås AS | Hospitality | 2024 |
| Norveducare Nuf | Education | 2022 |
| Norwatt AS | Financial services | 2016 |
| Norway Eiendom AS | Real estate | 2023 |
| Norway Solar AS | Professional & scientific | 2022 |
| NR 1 Catering AS | Hospitality | 2022 |
| NSB Utvikling AS | Real estate | 2018 |
| NT Partner Da Neraasen & Tandsether | Transport & logistics | 1991 |
| Nudas Veritas AS | Financial services | 2005 |
| Nutech AS | Real estate | 2017 |
| Nuvel AS | | 2014 |
| Nvpeiendom AS | Real estate | 2023 |
| NXT Catch AS | Professional & scientific | 2018 |
| NXT Invest AS | Professional & scientific | 2018 |
| Ny Kurs AS | Education | 2024 |
| Nydalsmarka I AS | Real estate | 2018 |
| Nydalsmarka II AS | Real estate | 2019 |
| Nydalsmarka III AS | Real estate | 2019 |
| Nydalsmarka V AS | Real estate | 2019 |
| Nygaard Tak & Bygg AS | Construction | 2008 |
| Nærby Invest AS | Real estate | 2005 |
| Næss Hjemmebakeri Ans | Manufacturing | 1996 |
| O Hansen AS | Wholesale & retail | 1963 |
| O Mustad & Søn AS | Manufacturing | 2003 |
| O Mustad & Søn Eiendom AS | Real estate | 1970 |
| Oa Trollhaugen AS | Professional & scientific | 2019 |
| Obc Eiendom AS | Professional & scientific | 2009 |
| Objektservice AS | Professional & scientific | 2012 |
| Odd Fellow Gården SA | Real estate | 1989 |
| Oddvar Kristiansen Holding AS | Manufacturing | 2005 |
| Okny AS | | 2024 |
| Olineberget AS | Health & social care | 2025 |
| Olivenhagen AS | Real estate | 2019 |
| Oliver Denk Holding AS | | 2025 |
| Olrudgruppen AS | Real estate | 2005 |
| Olrudgården Holding AS | Real estate | 2010 |
| Olve Finans AS | | 2025 |
| Oml Capital AS | Real estate | 2021 |
| Onb AS | Administrative & support | 2018 |
| One Stop Shop AS | Professional & scientific | 2012 |
| Onelove Invest AS | Information & communication | 2026 |
| Onsrud Invest AS | Financial services | 2005 |
| Oplandske AS | Professional & scientific | 2020 |
| Oppland Byggvask AS | Administrative & support | 2014 |
| Oppland Eiendom AS | Real estate | 2010 |
| Oppland Eiendomsutvikling AS | Construction | 2016 |
| Oppland Hagesenter AS | Wholesale & retail | 2020 |
| Oppland Interesser AS | Real estate | 1954 |
| Oppland Mur Og Flis AS | Construction | 2002 |
| Oppland Prosjekt Consult AS | Professional & scientific | 2014 |
| Opsahl Invest AS | Financial services | 2018 |
| Origo Byggprosjekt AS | Professional & scientific | 2006 |
| Orion Feb AS | Arts & recreation | 1991 |
| Ortofix Med Ans | Wholesale & retail | 2004 |
| Oscar Butikk Dagligvare AS | Wholesale & retail | 2018 |
| Osteosynthese AS | Health & social care | 2025 |
| Ottestad Butikkeiendom AS | Real estate | 2011 |
| Out of Band AS | Information & communication | 2025 |
| Out of Bounds Gjøvik AS | Real estate | 2020 |
| Output AS | Information & communication | 2022 |
| Over Skog Og Heiberg AS | Arts & recreation | 2012 |
| Ow Invest AS | Financial services | 2005 |
| Oxygen Gym AS | Arts & recreation | 2026 |
| P S AGENTUR Anne Kristine Pettersen og Svein Stafseng | | 1986 |
| P. Mauritz AS | | 2016 |
| Palm Holding AS | Financial services | 2005 |
| Panterpus AS | Health & social care | 2023 |
| Pantoglasses AS | Wholesale & retail | 2024 |
| Paradisvegen 2 AS | Real estate | 2024 |
| Parkgata 6 Gjøvik AS | Real estate | 2020 |
| Parkgata 81-85 AS | Real estate | 2018 |
| Parkgata AS | Real estate | 2015 |
| Parkgata Parkering AS | Real estate | 2022 |
| Partners Eiendomsmegling AS | Real estate | 2013 |
| Passiv Eiendom AS | Real estate | 2022 |
| Pc&T AS | Real estate | 2013 |
| Peder Ekrem AS | Financial services | 2012 |
| Peking Town Ans | Hospitality | 1993 |
| Per Braathen Eiendom AS | Real estate | 2005 |
| Percival Invest AS | Real estate | 1995 |
| Pers Rammeverksted AS | Manufacturing | 1987 |
| Persi Design AS | Wholesale & retail | 2025 |
| Pettersen-Moe Eiendom AS | Real estate | 1989 |
| PFR Bygg AS | Construction | 2025 |
| Pgmr AS | Information & communication | 2015 |
| PH Verdi AS | Wholesale & retail | 2005 |
| Phar Holding AS | Real estate | 2007 |
| Phe Holding AS | Health & social care | 2024 |