| Nedre Huseby 16 AS | | 2026 |
| Nemus Nittedal AS | Health & social care | 2012 |
| Nerheim AS | Real estate | 2019 |
| Nexta Biotech Consulting AS | Professional & scientific | 2024 |
| Ni Hao Nittedal Restaurant AS | Hospitality | 2021 |
| Nica Invest AS | Financial services | 2010 |
| Nitelva AS | | 2019 |
| Nitkon AS | Professional & scientific | 2022 |
| Nittedal Begravelsesbyrå AS | Other services | 2021 |
| Nittedal Bygg & Eiendom AS | Construction | 2016 |
| Nittedal Fysikalske Drift AS | Health & social care | 2019 |
| Nittedal Grafiske Ans | Manufacturing | 1989 |
| Nittedal Gårdsdrift Da | Agriculture & fishing | 2010 |
| Nittedal Hestesenter AS | Education | 2005 |
| Nittedal Karosseriverksted AS | Other services | 1996 |
| Nittedal Lakkering AS | Other services | 2020 |
| Nittedal Malerservice AS | Construction | 2022 |
| Nittedal Tak & Blikk AS | Construction | 2022 |
| Nittedal Tannlegesenter AS | Health & social care | 2020 |
| Nittedal Vask Og Renseri AS | Other services | 2015 |
| Nittedals Marketing Ltd AS | Real estate | 1978 |
| Nokab Holding AS | Information & communication | 2023 |
| Nordic XC AS | Arts & recreation | 2026 |
| Nordlys-Idé Da | Administrative & support | 2011 |
| Nordre Skøyen Gård AS | Real estate | 2023 |
| Norsk Kabel-Tv AS | Information & communication | 2015 |
| Norsk Medisin AS | Information & communication | 2016 |
| Norske Grønnsaker AS | Professional & scientific | 2017 |
| Novera Eiendom AS | Real estate | 2026 |
| Nye Smådyrklinikken I Nittedal AS | Professional & scientific | 2025 |
| Nøyd AS | Information & communication | 2023 |
| Oker AS | Other services | 2016 |
| Omstad Holding AS | Real estate | 2017 |
| Opdahl Invest AS | | 2026 |
| Oska AS | | 2021 |
| Oslo Sveisemek AS | Manufacturing | 2021 |
| Oss 3 Bilpleie Da | Other services | 2001 |
| Ottesen & Bjercke AS | Health & social care | 2025 |
| Ovi Invest AS | Professional & scientific | 2005 |
| P&O Vikarer AS | Administrative & support | 2021 |
| Pardus Invest AS | Wholesale & retail | 2021 |
| Paulin Holding AS | Financial services | 2018 |
| Pe Entreprenør AS | Construction | 2006 |
| Pellestova Apartments AS | Real estate | 2020 |
| Pema Snekkeri AS | Construction | 2019 |
| Personal Finance Management AS | Information & communication | 2026 |
| PHG AS | Real estate | 2016 |
| Platou Agency AS | | 2021 |
| Poter Og Prosent AS | Professional & scientific | 2025 |
| Pr-Elektro AS | Construction | 1986 |
| Praxis Learning AS | Information & communication | 2026 |
| Psykolog Sverre Sanden AS | Health & social care | 2023 |
| Punnerud AS | | 2005 |
| Pureokrs AS | Information & communication | 2020 |
| Pureplay AS | Wholesale & retail | 2019 |
| Pureplay Holding AS | Wholesale & retail | 2021 |
| Pureplay.No AS | Wholesale & retail | 2021 |
| Pynten & Midtun AS | Other services | 1987 |
| Pål Øksne AS | Construction | 1991 |
| Quintic Management AS | Professional & scientific | 2006 |
| Raadhuset Eiendom AS | Real estate | 2007 |
| Rajm Solutions AS | Information & communication | 2025 |
| RCG AS | Administrative & support | 2018 |
| RCG Drift AS | Real estate | 2018 |
| Reinsletta Bolig Og Eiendom AS | Information & communication | 2013 |
| Reir Solutions AS | Information & communication | 2024 |
| Restaurant & Cafe Gruppen AS | Wholesale & retail | 2012 |
| Riiser Holding AS | Professional & scientific | 2018 |
| Rita's Salong AS | Other services | 1987 |
| Rivolt AS | Professional & scientific | 1997 |
| Robøle Holding AS | | 2019 |
| Romerike Tak Og Blikk AS | Construction | 2011 |
| Rotnes Bruk AS | Real estate | 2006 |
| Rotnes Bruk Drift AS | Real estate | 2021 |
| Rotnes Bruk Holding AS | Real estate | 2021 |
| Rotnes Bruk Industri AS | Real estate | 2021 |
| Rotnes Fus Kulturbarnehage AS | Education | 2018 |
| Rotneshjørnet AS | Real estate | 1994 |
| Rotneslegene AS | Health & social care | 2003 |
| Rotneslegene Eiendom AS | Real estate | 2014 |
| Runar Alvseike Holding AS | | 2025 |
| RUS13 Holding AS | Construction | 2017 |
| Ryen Forvaltning AS | Real estate | 2007 |
| Rå Studio AS | Professional & scientific | 2023 |
| Sabi Holding AS | | 2020 |
| Said Benaissa AS | Wholesale & retail | 2001 |
| Salmon Aqualytiq AS | Information & communication | 2020 |
| Sandberg Holding AS | Real estate | 2016 |
| Sandberg Software AS | Information & communication | 2018 |
| Scanbur AS | Wholesale & retail | 1967 |
| Schmitz Holding AS | Transport & logistics | 2020 |
| Selska AS | | 2021 |
| Senter for Værekraft Da | Health & social care | 2025 |
| Seva Aesthetics AS | Health & social care | 2023 |
| Shield Asset & Risk Management AS | Professional & scientific | 2017 |
| Sivilingeniør Anders Haugen AS | Professional & scientific | 2012 |
| Siwchristine AS | Real estate | 2021 |
| Skagastølstind AS | Real estate | 2012 |
| Skanor Eiendom AS | Real estate | 2000 |
| Skjerstad Enterprises AS | Professional & scientific | 2022 |