| ND Real Estate II AS | Real estate | 2021 |
| Nea 1 Eiendom AS | Real estate | 2022 |
| Nea Gruppen AS | Wholesale & retail | 2016 |
| Nea Holding AS | Real estate | 2022 |
| Nel Hydrogen Electrolyser AS | Manufacturing | 2013 |
| Netauto AS | Wholesale & retail | 2006 |
| Netthandelparken AS | Real estate | 2021 |
| Nex-Hk AS | Real estate | 2026 |
| Nexe Holding AS | | 2005 |
| Next Anlegg AS | Construction | 2024 |
| Nivo-No Ans | Information & communication | 2004 |
| Nobo Utbygging AS | Real estate | 2012 |
| Nobygg AS | Construction | 2016 |
| Non Stop Da | Wholesale & retail | 1988 |
| Nordcat AS | Professional & scientific | 2021 |
| Nordic Aviation Maintenance AS | Manufacturing | 2020 |
| Nordic Flooring AS | Wholesale & retail | 2013 |
| Nordic-Gym AS | Arts & recreation | 2005 |
| Norfrag Tank Og Silo AS | Wholesale & retail | 2001 |
| Norpublica SA | Information & communication | 2016 |
| Norsk Fiskeeksport AS | Wholesale & retail | 2023 |
| Norsk Formblåsing AS | Manufacturing | 2008 |
| Norsk Fragmentering AS | Water & waste | 2003 |
| Norsk Vegverk AS | Construction | 2020 |
| Norsk-Eiendom AS | Real estate | 2015 |
| Norskmiljøintervensjon AS | Professional & scientific | 2025 |
| Northern Data Nor AS | Information & communication | 2020 |
| Norwegian Flying Aces AS | Administrative & support | 2017 |
| Notbygg AS | Construction | 2022 |
| Notodden Anleggsdrift AS | Construction | 2024 |
| Notodden Autoservice AS | Other services | 2026 |
| Notodden Begravelsesbyrå AS | Other services | 2003 |
| Notodden Bil Og Speedshop AS | Wholesale & retail | 1978 |
| Notodden Bilpleiesenter AS | Other services | 1990 |
| Notodden Blomster Og Import AS | Wholesale & retail | 2003 |
| Notodden Blues Band Da | Arts & recreation | 1997 |
| Notodden Bredbånd AS | Information & communication | 2001 |
| Notodden Bruktbil AS | Wholesale & retail | 2016 |
| Notodden Byggentreprenør AS | Construction | 2020 |
| Notodden Byggshop AS | Wholesale & retail | 2000 |
| Notodden Camping AS | Hospitality | 1992 |
| Notodden Dental AS | Health & social care | 1993 |
| Notodden Eiendom AS | Real estate | 2019 |
| Notodden Energi AS | Energy | 2012 |
| Notodden Energi Holding AS | Energy | 2012 |
| Notodden Event AS | Administrative & support | 2026 |
| Notodden Flyhangar AS | Real estate | 2006 |
| Notodden Flyinvest AS | Administrative & support | 1999 |
| Notodden Gjennbruk Da | Wholesale & retail | 2021 |
| Notodden Glass & Aluminium AS | Construction | 1987 |
| Notodden I Sentrum AS | Professional & scientific | 1998 |
| Notodden Industriselskap AS | Real estate | 1968 |
| Notodden Kiropraktorsenter AS | Health & social care | 2005 |
| Notodden Kobber & Blikk AS | Construction | 2018 |
| Notodden Kommunale Eiendomsutvikling AS | Real estate | 2022 |
| Notodden Limo & Eiendom AS | Real estate | 2024 |
| Notodden Lufthavn AS | Transport & logistics | 2002 |
| Notodden Lufthavn Eiendom AS | Transport & logistics | 2022 |
| Notodden Maskin & Utleie AS | Construction | 2012 |
| Notodden Og Omegn Tverrfaglige Opplæringskontor AS | Education | 2024 |
| Notodden Opplevelser AS | Administrative & support | 2023 |
| Notodden Optikk AS | Wholesale & retail | 2012 |
| Notodden Pukk AS | Mining & quarrying | 2018 |
| Notodden Regnskap AS | Professional & scientific | 2012 |
| Notodden Renovasjon & Gjenvinning AS | Water & waste | 1992 |
| Notodden Rens AS | Other services | 2014 |
| Notodden Rørleggerforretning AS | Construction | 1989 |
| Notodden Tapet Og Gulv AS | Construction | 2014 |
| Notodden Taxi SA | Transport & logistics | 1931 |
| Notodden Trafikkskole AS | Education | 2013 |
| Notodden Travpark AS | Real estate | 1990 |
| Notodden Utvikling AS | Professional & scientific | 1992 |
| Notodden Varmepumper AS | Construction | 2017 |
| Notodden Zoo AS | Wholesale & retail | 2022 |
| Notodden Øyelegesenter AS | Health & social care | 2020 |
| Notoxy AS | Hospitality | 2010 |
| Noxy Da | Wholesale & retail | 2006 |
| Nsar Baldr AS | Professional & scientific | 2026 |
| Nsar Group AS | | 2026 |
| Nybuvegen SA | Real estate | 2025 |
| Nye Hage Og Trepleie AS | Administrative & support | 2013 |
| Nye Li Bil AS | Real estate | 2018 |
| Nye Tuven Bilskade Eiendom AS | Real estate | 2026 |
| O V H Graving & Service AS | Administrative & support | 2014 |
| O-Lie AS | Financial services | 2012 |
| O.L. Skahjem AS | Real estate | 2014 |
| Oa Meyer Holding AS | Real estate | 2016 |
| Odel AS | Administrative & support | 2023 |
| Ogba AS | | 2020 |
| Okkos AS | Financial services | 2000 |
| Oko Elektro AS | Construction | 2022 |
| Oko Holding AS | Construction | 2022 |
| Olavsgate 7 Eiendom AS | Real estate | 2024 |
| Olivia Dagligvarer AS | Wholesale & retail | 2017 |
| Olsens Enke Notodden AS | Wholesale & retail | 2018 |
| Omnesfossen Eiendom AS | Real estate | 1994 |
| Omo Eiendom AS | Real estate | 1972 |
| Opaas Kompetansesenter AS | Education | 2013 |
| Optime Subsea AS | Mining & quarrying | 2005 |
| Optime Subsea Services AS | Professional & scientific | 2014 |