| Arisland Enterprises AS | Information & communication | 2013 |
| Arkem AS | Wholesale & retail | 2004 |
| Arl Consult AS | Information & communication | 2025 |
| Arm Capital AS | | 2026 |
| Arman Media AS | Information & communication | 2025 |
| Arman Media II AS | Information & communication | 2026 |
| Artinova AS | Manufacturing | 1989 |
| Artsteel AS | Manufacturing | 2023 |
| Artworx AS | Professional & scientific | 2022 |
| AS Fasaden | Real estate | 1974 |
| AS Kjærbo | Real estate | 1979 |
| AS Nybygg 1 | Households | 1954 |
| AS Skiltforum | Professional & scientific | 1982 |
| AS Østlandets Blad | Information & communication | 1920 |
| Askehaug Eiendom AS | Real estate | 2017 |
| Askehaug Eiendom II AS | Real estate | 2022 |
| Askim Næringseiendom AS | Real estate | 2022 |
| Aslam Bilservice AS | Wholesale & retail | 2008 |
| Assa Abloy Global Solutions Norway AS | Manufacturing | 1995 |
| Assa Abloy Norge AS | Wholesale & retail | 1997 |
| Assa Abloy Opening Solutions Norway AS | Wholesale & retail | 1983 |
| Assetfront AS | Information & communication | 2020 |
| Assist Ski AS | Wholesale & retail | 1995 |
| Assistor AS | Professional & scientific | 1988 |
| Ath Byggservice AS | Construction | 2013 |
| Ath Eiendomsdrift AS | | 2016 |
| Athlete Mindset AS | Arts & recreation | 2026 |
| Atlas Advisory AS | Professional & scientific | 2018 |
| Ato Eiendom AS | Construction | 2005 |
| Auditus Da | Professional & scientific | 2017 |
| Audun Opem Functional Safety Consulting AS | Professional & scientific | 2019 |
| Augmentor Impact Decisions AS | Professional & scientific | 2018 |
| Aurora Polar AS | Professional & scientific | 2016 |
| Austvik Holding AS | | 2025 |
| Authen Holding AS | | 2019 |
| Auto 24/7 AS | Wholesale & retail | 2024 |
| Auto E6 AS | Wholesale & retail | 1995 |
| Autoco Bilutleie AS | Administrative & support | 1983 |
| Automotordeler Ans | Wholesale & retail | 1997 |
| Autoplanet X AS | Wholesale & retail | 2024 |
| Autoportalen AS | Wholesale & retail | 1993 |
| Autoshine Ski AS | Other services | 2024 |
| Avako AS | Professional & scientific | 2005 |
| Aviant AS | Professional & scientific | 2020 |
| Avima Regnskap AS | Professional & scientific | 2017 |
| B & Grønvold AS | | 2025 |
| B D Invest AS | Real estate | 2015 |
| B. Amlien & Sønn A/S | Construction | 1986 |
| B.Grønvold AS | Professional & scientific | 2025 |
| Baderingen AS | Administrative & support | 1994 |
| Bafrin Frisør AS | Other services | 2013 |
| Bagge AS | | 2020 |
| Balal Storkiosk Og Video Ans | Wholesale & retail | 1996 |
| Balkan Pizza & Kebabhouse AS | Hospitality | 2001 |
| Baluba Bekledning AS | Professional & scientific | 2026 |
| Ban Consult AS | Real estate | 2020 |
| Ban Invest AS | | 2019 |
| Bare Hauglie AS | Arts & recreation | 2019 |
| Bare Kjuus AS | Arts & recreation | 2019 |
| Barnehuset Elle Melle Da | Wholesale & retail | 2002 |
| BB Ski AS | Hospitality | 2021 |
| BBB Investing AS | | 2023 |
| BBR Invest AS | | 2024 |
| BD Trafikkskole AS | Education | 2022 |
| Bee AS | Real estate | 2010 |
| Bee Kapital AS | Real estate | 2022 |
| Behandlerverket Ski AS | Health & social care | 2008 |
| Beic Invest AS | | 2025 |
| Bekkefaret AS | Construction | 2018 |
| Belcanto AS | Other services | 2022 |
| Benedikte Santi Holding AS | | 2025 |
| Benek Invest AS | Real estate | 2014 |
| Bentis Invest AS | | 2025 |
| Berg Eiendomsdrift AS | Real estate | 2017 |
| Berge Borthers Experience AS | Administrative & support | 2025 |
| Berghagan Holding AS | Real estate | 2021 |
| Bergmanns Ski AS | Hospitality | 2020 |
| Berryblue Invest AS | | 2025 |
| Besi Mur Og Graving AS | Construction | 2020 |
| Best Energi - Follo AS | Wholesale & retail | 2010 |
| Beves AS | Financial services | 2017 |
| Bi Holding AS | Financial services | 2005 |
| Bil & Last AS | Transport & logistics | 2018 |
| Bila Bygg & Element AS | Construction | 2012 |
| Bilhospitalet AS | Other services | 2015 |
| Biltunet Verksted AS | Other services | 2005 |
| Bilverkstedet AS | Other services | 2004 |
| Bingo Holding AS | Information & communication | 2019 |
| Biohage AS | Wholesale & retail | 2024 |
| Birkeland Holding AS | Construction | 2018 |
| Birkeland Takst & Prosjekt AS | Real estate | 2022 |
| Bjaf Eiendom AS | Real estate | 2025 |
| Bjojoh Holding AS | Real estate | 2020 |
| Bjørn Riiser Consulting AS | Information & communication | 2016 |
| Bjørnstad Servicepartner AS | Information & communication | 2012 |
| Blackstone AS | | 2005 |
| Blokhus Reklame Montasje AS | Professional & scientific | 2020 |
| Bloom Studio AS | Other services | 2026 |
| Blålykke AS | Administrative & support | 2024 |
| Bmcon AS | Information & communication | 2006 |