| 1 Eiendom AS | Real estate | 2015 |
| A Nielsen Trafikkskole AS | Education | 1994 |
| Aarbakk Athena Holding AS | | 2025 |
| Aarbakk Holding AS | | 2025 |
| Aarbakk Maskin AS | Construction | 2008 |
| Aarbakke Invest AS | | 2020 |
| Aas Maskin AS | Construction | 2015 |
| Aasekaasen Service AS | Professional & scientific | 2024 |
| Aasen & Ingolfsrud Da | Construction | 2001 |
| Aaseservice AS | Professional & scientific | 2018 |
| Ace Group AS | Professional & scientific | 2020 |
| Advanced Thinkers Engineering AS | Professional & scientific | 2003 |
| Advokat Frisak Wallin AS | Professional & scientific | 2021 |
| Advokatfirmaet Algeroy AS | Professional & scientific | 2019 |
| Advokatfirmaet Slettebø AS | Professional & scientific | 2019 |
| Ae Eiendom AS | Construction | 1998 |
| Aek Invest AS | Real estate | 2005 |
| Agder Lagerpark AS | Real estate | 2014 |
| Agk Invest AS | Administrative & support | 2008 |
| Ah Eiendomsdrift AS | Real estate | 2012 |
| Aiir AS | Wholesale & retail | 2014 |
| Ak Regnskap Nystad AS | Professional & scientific | 2018 |
| Aktivitetsplanleggeren AS | Professional & scientific | 2023 |
| Alfacare AS | Wholesale & retail | 2002 |
| Alfacare International AS | Real estate | 2021 |
| Alfagroup AS | Wholesale & retail | 2021 |
| ALL4SPAS AS | Wholesale & retail | 2014 |
| ALL4SPAS Eiendom AS | Real estate | 2019 |
| Alseth Anlegg AS | | 2020 |
| Altitall AS | Professional & scientific | 2021 |
| Andersen Bil Og Bilskade AS | Other services | 2012 |
| Ane Bakken AS | Financial services | 2020 |
| Ann Kristin Torjesen AS | Health & social care | 2014 |
| Ans Notodden Import | Wholesale & retail | 1990 |
| Anundskås Og Haatveit Eiendom AS | Wholesale & retail | 2007 |
| Anwi Holding AS | | 2005 |
| Arhol AS | Administrative & support | 2022 |
| Arve Bakken AS | Wholesale & retail | 2005 |
| Arvesen Eiendom AS | Real estate | 1982 |
| AS Rupa | Real estate | 1908 |
| Asanjo Da | Professional & scientific | 2006 |
| Asta Konsulenter AS | Professional & scientific | 2019 |
| Asta Utvikling AS | Real estate | 2019 |
| Atelier Grøstad Arkitektur AS | Professional & scientific | 1987 |
| Atomiccircus Da | Other services | 2011 |
| Auto Bilnett AS | Wholesale & retail | 2019 |
| Auto Control AS | Wholesale & retail | 2024 |
| Auto Gruppen AS | Wholesale & retail | 2016 |
| Auto S Motor & Marine AS | Wholesale & retail | 2015 |
| Auto S Notodden AS | Other services | 2011 |
| Autostrada Notodden AS | Wholesale & retail | 1988 |
| Aw Consulting AS | Wholesale & retail | 2016 |
| Asbjørn J. Hansen A/S | Manufacturing | 1988 |
| B Selmer AS | Real estate | 2012 |
| Bakken AS | Wholesale & retail | 1989 |
| Bakken Industrier AS | Transport & logistics | 2021 |
| Bakken Tuning & Bil AS | Other services | 2016 |
| Baldrian Holding AS | | 2025 |
| Bandak NCT AS | Manufacturing | 2017 |
| Baneanlegg AS | Construction | 2023 |
| Barøfoss Invest AS | Wholesale & retail | 2005 |
| Bas-Eiendom AS | Real estate | 2017 |
| Bauge Entreprenør AS | Construction | 2005 |
| Bekkhus Utleie Og Handel AS | Administrative & support | 2025 |
| Belania Holding AS | Real estate | 2006 |
| Bellman Eiendom AS | Real estate | 2024 |
| Bellman Event AS | Arts & recreation | 2025 |
| Bellman Pub AS | Hospitality | 2012 |
| Berge Consulting AS | Professional & scientific | 2026 |
| Berget Holding AS | Financial services | 2005 |
| Betania Barnehage AS | Education | 2013 |
| Betongarbeideren AS | Construction | 2014 |
| Betongpumperen AS | Transport & logistics | 2012 |
| BF Entreprenør AS | Construction | 2014 |
| Bil & Dekkimport AS | Wholesale & retail | 1997 |
| Bilutstyr Tuven AS | Wholesale & retail | 2000 |
| Birkeland Skaperverksted AS | Professional & scientific | 2021 |
| Bjarnason Eiendom AS | Real estate | 2006 |
| Bjarnasonbygget AS | Real estate | 2012 |
| Bjarne Evensen Eiendom AS | Construction | 2006 |
| Bjarne Evensen Holding AS | Construction | 2005 |
| Bjønndalsrullen SA | Real estate | 2001 |
| Bjørnstjerne Bjørnsons Gate 4 AS | Real estate | 2022 |
| Bjørnstjerne Bjørnsons Gate 8A AS | Real estate | 2020 |
| Bjørnstjerne Bjørnsons Gate 8B AS | Real estate | 2020 |
| Bjørnstjerne Bjørnsonsgate 5 AS | Real estate | 1967 |
| BK Anleggsservice AS | Construction | 2014 |
| BK Notodden AS | Hospitality | 2019 |
| BK Pukk AS | Mining & quarrying | 2022 |
| BK Utvikling AS | Real estate | 2020 |
| Blanchard Holding AS | | 2024 |
| Bm-Solutions AS | Construction | 2025 |
| Bohus Notodden AS | Wholesale & retail | 2004 |
| Boligeiendom AS | Real estate | 1988 |
| Bolkesjø Eiendom AS | Real estate | 2017 |
| Bolkesjø Taxi AS | Transport & logistics | 2025 |
| Boneshock Studio AS | Information & communication | 2023 |
| Braafjord Classic AS | Transport & logistics | 2025 |
| Braafjord Eiendom AS | Real estate | 2024 |
| Braided Rope AS | Manufacturing | 2024 |