| 1916 Invest AS | Real estate | 2020 |
| 911 Holding AS | Wholesale & retail | 2010 |
| A&B Renhold AS | Administrative & support | 2016 |
| A-Data AS | Real estate | 1984 |
| A. Aam AS | Other services | 2024 |
| A. Grønvold Holding AS | Construction | 2024 |
| Aas Rekruttering AS | Administrative & support | 2025 |
| Abeko AS | Construction | 2025 |
| Abello Style & Trends AS | Wholesale & retail | 2026 |
| Abiramy AS | Wholesale & retail | 2018 |
| Acaraho Consulting AS | Professional & scientific | 2014 |
| Addicted AS | | 2021 |
| Aettegaard AS | Real estate | 2006 |
| Akira AS | Other services | 2018 |
| Aleksander Blikshavn AS | Health & social care | 2022 |
| Alka Eiendom AS | Real estate | 2012 |
| Allstein AS | Manufacturing | 1996 |
| Alna AS | Manufacturing | 2002 |
| Alnabru Invest AS | Wholesale & retail | 2020 |
| Alot Trans AS | Transport & logistics | 2022 |
| Alpenheim AS | Real estate | 2026 |
| Alpenheim Holding AS | | 2026 |
| Alto Byggservice AS | Construction | 2021 |
| Alulu Holding AS | Information & communication | 2026 |
| Always Open AS | | 2024 |
| Andresen Multiservice AS | Administrative & support | 2019 |
| Ankerløkken AS | Wholesale & retail | 2005 |
| Ankr Holding AS | | 2023 |
| Annette & Christian AS | Professional & scientific | 2012 |
| Annette Nordstrøm AS | Professional & scientific | 2017 |
| Anniken Isaksen Holding AS | | 2021 |
| Annyha Holding AS | | 2025 |
| Aoma Handel AS | Wholesale & retail | 2025 |
| Aoma Holding AS | Wholesale & retail | 2019 |
| Apatre AS | | 2020 |
| Arctic Hazard AS | Information & communication | 2022 |
| Arctic Hazard Game Studio AS | Manufacturing | 2010 |
| Arctic Hazard Holding AS | Information & communication | 2022 |
| Arctic Mining Rental AS | Administrative & support | 2026 |
| Arena Catering AS | Hospitality | 2012 |
| Arg Brands AS | Wholesale & retail | 2009 |
| Arktek VVS AS | Construction | 2023 |
| AS Malmbergs Elektriske | Wholesale & retail | 1987 |
| Asko Bygg Vestby AS | Wholesale & retail | 2002 |
| Asko Maritime AS | Transport & logistics | 2020 |
| Asko Sentrallager Kjøl AS | Wholesale & retail | 2015 |
| Asko Sentrallager Og Transport AS | Wholesale & retail | 2008 |
| Asko Øst AS | Wholesale & retail | 1962 |
| Aslam Bilservice Da | Wholesale & retail | 2004 |
| Atlas Copco AS | Real estate | 1916 |
| Atlas Copco Kompressorteknikk AS | Wholesale & retail | 1989 |
| Atlas Copco Power Technique Nordic | Wholesale & retail | 2017 |
| Atlas Copco Tools AS | Wholesale & retail | 1983 |
| Autismelivet AS | Education | 2021 |
| Auto Sonic Norge AS | Wholesale & retail | 2017 |
| Auto Viken AS | Wholesale & retail | 2021 |
| Autobahn Holding AS | | 2024 |
| Autocirc Vestby AS | Wholesale & retail | 2023 |
| Autonett Vestby AS | Wholesale & retail | 2025 |
| Autotuning AS | Wholesale & retail | 2022 |
| Autotuning Motorsport AS | Wholesale & retail | 2016 |
| Autotuning Sport AS | Wholesale & retail | 2021 |
| Autotuning Sportcars AS | Wholesale & retail | 2026 |
| Avero AS | Wholesale & retail | 2012 |
| Aware Moto Racing AS | Arts & recreation | 2024 |
| Axels Tivoli Park AS | Arts & recreation | 2009 |
| B & C Designsnekkeri AS | Construction | 2020 |
| B. E. Opheim Holding AS | Health & social care | 2023 |
| Babylon Pizza Vestby AS | Hospitality | 2016 |
| Bahnhof AS | Information & communication | 2003 |
| Baklyset AS | Information & communication | 2025 |
| Baksjøbygg Og Anlegg AS | Construction | 2023 |
| Balder Engineering AS | Professional & scientific | 2012 |
| Bargoo Invest AS | | 2023 |
| Barnas Sundbytoppen AS | Education | 2022 |
| Barnehagegården Vestby Naturbarnehage AS | Education | 2022 |
| BD Holding 2.0 AS | | 2026 |
| Beauty Eiendom AS | Real estate | 2009 |
| Beauty Products AS | Wholesale & retail | 1978 |
| Beauty Products Thorsen AS | Wholesale & retail | 1993 |
| Beca Eiendom AS | Real estate | 2020 |
| Ber Eiendomsutvikling AS | Real estate | 2025 |
| Berger Eiendom AS | Real estate | 1996 |
| Bergsprenger AS | Construction | 2013 |
| Beste Holding AS | Professional & scientific | 2016 |
| Beste Invest AS | | 2021 |
| Bestemor Eiendom AS | Wholesale & retail | 2015 |
| Besth Invest AS | Real estate | 2006 |
| Bibis AS | Real estate | 2019 |
| Biesterfeld Norge AS | Wholesale & retail | 1984 |
| Biloutlet AS | Wholesale & retail | 2024 |
| Bioactive Foods AS | Professional & scientific | 2011 |
| Birkelunden Eiendomsselskap AS | Real estate | 2021 |
| Birkelunden Investeringsselskap AS | Wholesale & retail | 2018 |
| Bjerkehagen Tomteselskap AS | Real estate | 2012 |
| Bjune Engineering Da | Professional & scientific | 2003 |
| Bjørkekollen Barnehage AS | Education | 2022 |
| Bjørnstad Sport AS | Wholesale & retail | 2012 |
| Bli Ren Topco AS | | 2026 |
| Blikkenslager Haram AS | Construction | 2020 |