| Bilressurs AS | Wholesale & retail | 2007 |
| Bilspa 1 Moss AS | Other services | 2019 |
| Binary AS | Information & communication | 2012 |
| Binary Eiendom AS | Real estate | 2025 |
| Bingedammen AS | Real estate | 2008 |
| Bingo 1 AS | Arts & recreation | 2007 |
| Bioflame AS | Wholesale & retail | 2020 |
| Birdie Bliss Golf AS | Education | 2023 |
| Bistech AS | Information & communication | 2021 |
| Bit Logistikk AS | | 2026 |
| Bjarne Egedesø | Wholesale & retail | 2005 |
| Bjerka Park AS | Real estate | 2025 |
| Bjørn C. AS | Wholesale & retail | 1993 |
| Bjørn M. Haug Transport AS | Transport & logistics | 2012 |
| Bjørnstad Entreprenørpark AS | Real estate | 2015 |
| BK Creative Holding AS | | 2026 |
| BKM Holding AS | | 2013 |
| Blacklink Networks AS | Professional & scientific | 2019 |
| Blakli AS | | 2025 |
| Blank Studio AS | Professional & scientific | 2024 |
| Blckmny AS | Information & communication | 2024 |
| Blender Invest AS | Real estate | 2003 |
| Blixøen Holding AS | Real estate | 2017 |
| Blizz-Tech AS | Information & communication | 2025 |
| Blodbøken AS | Financial services | 2006 |
| Blomfeldt Holding AS | Wholesale & retail | 2007 |
| Blomster Pia AS | Wholesale & retail | 2013 |
| Blue Vision Bedriftsrådgivning AS | Professional & scientific | 2024 |
| Blå Hånd Eiendom AS | Real estate | 2022 |
| Blåklader AS | Wholesale & retail | 1895 |
| Blø AS | Professional & scientific | 2024 |
| BM Urstad Holding AS | Construction | 2024 |
| BMG Eiendom AS | Real estate | 2010 |
| BN Import AS | Wholesale & retail | 2014 |
| BN Sport Norge Ans | Wholesale & retail | 2001 |
| Bob Trafikkskole AS | Education | 2007 |
| Bodypop AS | Manufacturing | 2018 |
| Boh Invest AS | Real estate | 2015 |
| Bohlin Prosjekt AS | Construction | 2021 |
| Bokholderiet AS | Professional & scientific | 1981 |
| Bold Holding AS | | 2024 |
| Bold Mum AS | Professional & scientific | 2019 |
| Bolig & Betong AS | Construction | 2025 |
| Boligbygg Norge AS | Real estate | 2025 |
| Boligbørsen Da | Information & communication | 2004 |
| Boligcompagniet AS | Real estate | 2023 |
| Boligvask AS | Administrative & support | 2023 |
| Borchbio AS | Information & communication | 1998 |
| Boreas Invest AS | Professional & scientific | 2015 |
| Borgaas Invest AS | Real estate | 2006 |
| Borgstena of Sweden AS | Wholesale & retail | 2011 |
| BOUTIQUE1854 AS | Wholesale & retail | 2016 |
| Boviken AS | | 2023 |
| Brandstrup Holding AS | Arts & recreation | 2005 |
| Branlit AS | Education | 2024 |
| Brectus AS | Professional & scientific | 2019 |
| Brectus Holding AS | Professional & scientific | 2014 |
| Bredman & Jensen Ans | Construction | 1992 |
| Bredsand Butikkeiendom AS | Real estate | 2012 |
| Bredsand Invest AS | | 2026 |
| Brehmergaarden AS | Real estate | 2018 |
| Brekke-Hammersland AS | | 2025 |
| Brennes Auto Moss AS | Wholesale & retail | 2009 |
| Brennum Invest AS | Real estate | 2010 |
| Brenx AS | | 2022 |
| Bretun Holding AS | Real estate | 2014 |
| Bretun Interiør AS | Wholesale & retail | 1980 |
| Bretun Interiør Eiendom AS | Real estate | 2005 |
| Bretun Proff AS | Wholesale & retail | 2025 |
| Bretun Tak AS | Construction | 2024 |
| Brinkmann & Bredahl Marine AS | Manufacturing | 2018 |
| Bro Holding AS | Financial services | 2005 |
| Brodd AS | Real estate | 2005 |
| Brogård Renhold AS | Administrative & support | 2014 |
| Bromander Invest AS | | 2018 |
| Brun Selected Wines AS | Wholesale & retail | 2025 |
| Bråtengata 2 AS | Real estate | 2022 |
| Bråtengaten 19 Ans | Real estate | 2002 |
| Bråtenstua Barnehage SA | Education | 1995 |
| Brødr Mathisen AS | Real estate | 1992 |
| Brødrene Bygg AS | Construction | 2024 |
| Brødrene Børresen Holding AS | | 2022 |
| Brødrene Mollatt Ans | Real estate | 2010 |
| Brødrene Peterson AS | Real estate | 2020 |
| Brødrene Reier AS | Agriculture & fishing | 1981 |
| Brønnhøydåsen AS | Real estate | 2017 |
| BS Medie AS | Administrative & support | 2024 |
| Bsa - Business Support & Analysis AS | Professional & scientific | 2016 |
| BSG Eiendom AS | Real estate | 2026 |
| BSR Bygg AS | Construction | 2026 |
| Buberg Consulting AS | Financial services | 2005 |
| Bubis AS | | 2018 |
| Bui Eiendom AS | Real estate | 2021 |
| Bui Invest Holding AS | | 2021 |
| Bui Solutions AS | Real estate | 2026 |
| Buk Merch AS | Wholesale & retail | 2020 |
| Bukatek Invest AS | Real estate | 2006 |
| Bullbear AS | Financial services | 2020 |
| Bunnpris Glassverket AS | Wholesale & retail | 2021 |
| Buro Holding AS | Information & communication | 2025 |