| Boss AS | Wholesale & retail | 2008 |
| Boss Barber AS | Other services | 2021 |
| Boss Holding AS | Real estate | 2005 |
| Boston Tea Party Mini Big Band Ans | Arts & recreation | 1999 |
| Botngård Park AS | Real estate | 2015 |
| Botten Bruk AS | Construction | 2013 |
| Bourbon Rails Ans | Manufacturing | 2017 |
| Boutique Bello AS | Wholesale & retail | 1995 |
| Bovekst Invest AS | | 2005 |
| Bovida AS | Wholesale & retail | 1991 |
| Box Brud AS | Wholesale & retail | 2018 |
| Box Frisør AS | Other services | 2015 |
| Boxers AS | Wholesale & retail | 2011 |
| Boxit AS | Wholesale & retail | 2024 |
| BP Bratsberg AS | Real estate | 2024 |
| BP Eiendommer AS | Real estate | 2024 |
| BP Entreprenør AS | Construction | 2013 |
| BP Gruppen AS | Construction | 2024 |
| BP Maskinutleie AS | Administrative & support | 2024 |
| BP Sveberg AS | Real estate | 2024 |
| BPT Miljø AS | Construction | 2026 |
| BR Music AS | Arts & recreation | 2019 |
| BR Raaken AS | Construction | 2002 |
| BR. Tellefsen AS | Construction | 2003 |
| Brage Stjern Ans | Professional & scientific | 2023 |
| Brage Stjern AS | Professional & scientific | 1994 |
| Brageva AS | Health & social care | 2016 |
| Brainsync AS | Information & communication | 2024 |
| Brame Holding AS | | 2025 |
| Brand Studio AS | Wholesale & retail | 2022 |
| Brandhaugveita 1 AS | Real estate | 2020 |
| Brandmo AS | Information & communication | 2015 |
| Brando AS | Wholesale & retail | 1994 |
| Brando Kids AS | Wholesale & retail | 2001 |
| Brandre AS | Information & communication | 2022 |
| Brandscout AS | Information & communication | 2026 |
| Brannrådgiverne AS | Professional & scientific | 2012 |
| Brasilia Trondheim AS | Hospitality | 2021 |
| Brasseri Cava AS | Hospitality | 2005 |
| Bratbak Consulting AS | Professional & scientific | 2019 |
| Bratlien Invest AS | | 2021 |
| Bratsberg Fus Kulturbarnehage AS | Education | 2019 |
| Bratsbergvegen 2 AS | Real estate | 2005 |
| Bratsbergveien 11-15 AS | Real estate | 1952 |
| Bratt & Co AS | Professional & scientific | 1990 |
| Brattbakken Invest AS | | 2025 |
| Brattfoss Holding AS | | 2025 |
| Brattset Holding AS | Financial services | 2005 |
| Brattøra Ski/Sykkel Service AS | Wholesale & retail | 2020 |
| Brattørgata 1 AS | Real estate | 2015 |
| Brattørgata 12 B AS | Real estate | 2005 |
| Brattørgata 3A AS | Real estate | 1991 |
| Brattørgata 7 AS | Real estate | 2007 |
| Brattørgata Eiendom AS | Real estate | 2014 |
| Brattørkaia 13B AS | Real estate | 2016 |
| Brattørkaia AS | Real estate | 2006 |
| Brauten Eiendom AS | Professional & scientific | 2016 |
| Bravi Entreprenør AS | Construction | 2026 |
| Bravomedia AS | Professional & scientific | 2020 |
| Bre Consult AS | Information & communication | 2017 |
| Breach AS | Information & communication | 2016 |
| Brechan Rør AS | Construction | 1995 |
| Brede Holding AS | | 2024 |
| Bredeveien Bygg AS | Construction | 2022 |
| Bredland AS | | 2004 |
| Bredmyra Eiendom Invest AS | Real estate | 2011 |
| Brehme Holding AS | | 2023 |
| Breidablik Bolig & Eiendom AS | Real estate | 2012 |
| Breidablikveien 3 AS | Real estate | 2022 |
| Brekke Industrier AS | Real estate | 1991 |
| Brekke Invest AS | | 2008 |
| Brem AS | Real estate | 2016 |
| Bremz Holding AS | | 2025 |
| Brendeland & Kristoffersen Arkitekter AS | Professional & scientific | 2002 |
| Brennvall Holding AS | Professional & scientific | 2007 |
| Breol Eiendom AS | Real estate | 2015 |
| Breol Holding AS | Real estate | 2025 |
| Brettel AS | Real estate | 2015 |
| Brettel Pa AS | Real estate | 2015 |
| Brettel Reklame AS | Professional & scientific | 1978 |
| Brettel Økonomi AS | Professional & scientific | 1990 |
| Bretun Fysioterapi AS | Health & social care | 2022 |
| Brevik Boligutleie AS | Real estate | 2017 |
| Brevik Boligutleie Weidemannsveien 9 AS | Real estate | 2007 |
| Brevik Eiendom Ans | Real estate | 1998 |
| Brew Lab AS | Wholesale & retail | 2015 |
| Brewhouse AS | Wholesale & retail | 2021 |
| Brids Holding AS | | 2020 |
| Brightbeam AS | Information & communication | 2024 |
| Brighten AS | Administrative & support | 2025 |
| Briks AS | Information & communication | 2017 |
| Brilla Institutt AS | Education | 2016 |
| Brillan Holding AS | Professional & scientific | 2016 |
| Brilliant AS | Information & communication | 2013 |
| Briskebyveien 48 AS | Real estate | 2017 |
| Bristol Conditori AS | Hospitality | 1985 |
| Britannia Eiendom AS | Real estate | 2014 |
| Britannia Hotel AS | Hospitality | 2016 |
| Britha AS | Other services | 2021 |
| Britha Eiendom AS | Real estate | 2026 |