| Aschim Dataconsult Og Invest AS | Information & communication | 2018 |
| Aschim Eiendom AS | Information & communication | 1975 |
| Asker & Bærum Hus AS | Construction | 1994 |
| Asker Og Bærum Eiendomsutvikling AS | Professional & scientific | 2014 |
| Asker Sentrum Eiendom AS | Real estate | 2021 |
| Aspector AS | Information & communication | 2000 |
| Asplin Consulting and Safari AS | Professional & scientific | 2018 |
| Astina AS | | 2022 |
| Atom Investments AS | Professional & scientific | 2025 |
| Atom Rørleggerbedrifts AS | Construction | 2019 |
| Atomas Holding AS | | 2021 |
| Audionova AS | Health & social care | 2005 |
| Auditco AS | Professional & scientific | 2016 |
| Aurelius Invest AS | Financial services | 2018 |
| Aurelius Maximus AS | | 2026 |
| Auriculi Drift AS | Health & social care | 2024 |
| Aurnelia AS | | 2022 |
| Aurora Ventures AS | | 2026 |
| Austin Invest AS | Real estate | 2014 |
| Autokjemi AS | Wholesale & retail | 2011 |
| Awf Invest AS | | 2023 |
| B & W Group Ltd | Professional & scientific | 2003 |
| B 17 Eiendom AS | Real estate | 2017 |
| B Good Industries AS | | 2023 |
| B&K Oppussing AS | Construction | 2019 |
| Ba Råd Bjørn Andvig AS | Professional & scientific | 1998 |
| Babybelly AS | Professional & scientific | 2021 |
| Bakkegrenda AS | Real estate | 2022 |
| Balansedans AS | Education | 2016 |
| Ballerud Golf Og Treningssenter AS | Arts & recreation | 1992 |
| Base Rådgivning AS | | 2019 |
| Basic Info Nuf | Professional & scientific | 2007 |
| Baumann Industrier AS | Financial services | 1981 |
| BB Company AS | Professional & scientific | 2020 |
| BC Verksted AS | Other services | 2018 |
| BDR Entreprenør AS | Professional & scientific | 2026 |
| Bebe Invest AS | Real estate | 2010 |
| Beford AS | Professional & scientific | 1997 |
| Beka Ans | Construction | 2002 |
| Beluja Ans | Construction | 2003 |
| Beluna AS | | 2005 |
| Benkestokk Holding AS | | 2022 |
| Bente-Marie Ihlen AS | Health & social care | 2007 |
| Bentley Systems Scandinavia Nuf | Information & communication | 1996 |
| Bergh Consulting AS | Education | 2020 |
| Bernard Bygg AS | Construction | 2020 |
| Bero Ans | Construction | 2001 |
| Betterair AS | Professional & scientific | 2019 |
| BF Økonomi AS | Professional & scientific | 2020 |
| Bildeal AS | Professional & scientific | 2021 |
| Bilklar AS | Other services | 2026 |
| Bilkosmetikk AS | Other services | 2011 |
| Billingstad Bolig AS | Real estate | 2020 |
| Bionobil AS | Energy | 2023 |
| Bislett Invest Eiendom AS | Real estate | 1998 |
| Bitten AS | Wholesale & retail | 1987 |
| Bjelke Eiendom AS | Real estate | 2008 |
| Bjerk Eiendom AS | Professional & scientific | 2019 |
| Bjerk Utvikling AS | Professional & scientific | 2019 |
| Bjerkmann Thue & Johansen BADEROM1 AS | Construction | 2003 |
| Bjørnebu AS | Real estate | 2006 |
| Bjørsinvest AS | | 2025 |
| Bknudtzen Holding AS | | 2020 |
| BLL Økonomisk Rådgivning AS | Professional & scientific | 1983 |
| Blommenholm Eiendomsutvikling AS | Real estate | 2005 |
| Blommenholm Motorverksted AS | Manufacturing | 1998 |
| Blue Line Norway AS | Wholesale & retail | 2023 |
| Bobbysox AS | | 2020 |
| Boganes Consulting AS | Information & communication | 2024 |
| Bokka AS | Financial services | 2005 |
| Bolder Nor AS | Administrative & support | 2019 |
| Boligagenten AS | Real estate | 2004 |
| Boligforvandling AS | Manufacturing | 2012 |
| Bolærnebåtene AS | Transport & logistics | 2017 |
| Bomont AS | Real estate | 2017 |
| Bomont Eiendom Osb AS | Real estate | 2018 |
| Bomont Entreprenør AS | Construction | 2018 |
| Bomont Holding AS | Construction | 2018 |
| Boneman Holding AS | Manufacturing | 2020 |
| Bonjour Invest AS | | 2019 |
| Bookea Vulkanisterna AS | Information & communication | 2021 |
| Borinken AS | Real estate | 2017 |
| Brambani Økonomi AS | Administrative & support | 1998 |
| Brinken 20 Næring AS | Real estate | 2006 |
| Brinken Holding AS | Real estate | 2006 |
| Brioche AS | Professional & scientific | 2024 |
| Brioche Fiction AS | Information & communication | 2026 |
| Brokkr AS | | 2020 |
| Bruhn Klima AS | Construction | 2026 |
| Brumm 1 Ans | Real estate | 2003 |
| Brumm 5 Ans | Real estate | 2004 |
| Bryhn Invest AS | Real estate | 1989 |
| Brødrene Thorsvik AS | Transport & logistics | 1993 |
| BSL Holding AS | Financial services | 2008 |
| Burger Venture AS | Hospitality | 2015 |
| Busmo AS | Professional & scientific | 2005 |
| Bwood AS | Manufacturing | 2013 |
| Bygg Og Energi AS | Construction | 1993 |
| Bygg Support Norden AS | Construction | 2020 |
| Byggaksess Norge AS | Construction | 2012 |