| Autolakk Eiendom Moss AS | Real estate | 2021 |
| Autolakk Moss AS | Other services | 2021 |
| Automotiv AS | Wholesale & retail | 2021 |
| Autoprotect AS | Other services | 2005 |
| Autopuls AS | Other services | 2014 |
| Autoservice Moss AS | Wholesale & retail | 2010 |
| Autoskadesenteret HM1 AS | Other services | 2012 |
| Avacs AS | Construction | 2020 |
| Avance Nordic AS | Professional & scientific | 2017 |
| Avani Design AS | Wholesale & retail | 2017 |
| Avavi AS | Construction | 2002 |
| Aventi Bil AS | Wholesale & retail | 2025 |
| Avercabron AS | Education | 2026 |
| Avisyd AS | Professional & scientific | 2019 |
| Axel Capital AS | | 2025 |
| Ayetrack AS | Information & communication | 2025 |
| Az Bilservice AS | Other services | 2014 |
| Aktieselskapet Rosnæs | Real estate | 1931 |
| B Team Invest AS | Professional & scientific | 1994 |
| B-Holding AS | Construction | 2005 |
| B. Ali Holding AS | | 2021 |
| B. Andresen Holding AS | Real estate | 2005 |
| B. Andresen Ur-Optikk AS | Wholesale & retail | 2005 |
| B.T. Jensen Holding AS | Real estate | 2017 |
| B2B Solutions AS | Administrative & support | 2021 |
| Baardsen International Aviation Consulting AS | Transport & logistics | 2012 |
| Baba Sushi Lilleeng AS | Hospitality | 2020 |
| Baba Sushi Moss AS | Manufacturing | 2014 |
| Baguetten AS | Wholesale & retail | 2015 |
| Bakkerud Holding AS | | 2019 |
| Bakkeveien 15 AS | Professional & scientific | 2023 |
| Balco Holding AS | | 2025 |
| Balticum Frinab AS | Wholesale & retail | 1985 |
| Bamarni Holding AS | Hospitality | 2012 |
| Bambus Klær AS | Wholesale & retail | 2014 |
| Bankveien 24 Holding AS | Real estate | 2024 |
| Banzai Da | Hospitality | 1996 |
| Barber Shop Høyda AS | Other services | 2025 |
| Barbershop H&A I Mosseporten AS | Other services | 2020 |
| Barrusx AS | Administrative & support | 2012 |
| Basaren Eiendom AS | Real estate | 2015 |
| Basor AS | Wholesale & retail | 2014 |
| Bassengspesialisten AS | Construction | 2015 |
| Bato AS | Financial services | 2006 |
| Bauter AS | Arts & recreation | 2017 |
| BB Roads AS | Administrative & support | 2023 |
| BCB Formidling AS | Wholesale & retail | 2021 |
| BCC Property AS | Real estate | 2022 |
| BCC Property Holding AS | Real estate | 2022 |
| BCN Invest AS | | 2020 |
| Be-Mo Service & Reparasjoner AS | Administrative & support | 2020 |
| Bea Møbler AS | Wholesale & retail | 2005 |
| Bea Norge AS | Wholesale & retail | 1985 |
| Beauty Clinic AS | Other services | 2021 |
| Beauty Company AS | Wholesale & retail | 2017 |
| Beauty Holding AS | Wholesale & retail | 2017 |
| Beauty Shot AS | Other services | 2020 |
| Beauty Skin Clinic AS | Other services | 2018 |
| Beautynails AS | Other services | 2014 |
| Bedre Bolig AS | Wholesale & retail | 2005 |
| Bedriftsøkonomi AS | Professional & scientific | 2016 |
| Begby & Vollebæk Da | Wholesale & retail | 1997 |
| Bekke AS | Real estate | 2015 |
| Bekkefaret Garasjelag Moss SA | Transport & logistics | 2006 |
| Bekkinga Utemøbler AS | Manufacturing | 2021 |
| Belgen Økonomitjenester AS | Professional & scientific | 2021 |
| Belu Invest AS | Financial services | 2017 |
| Bema Eiendom Ans | Real estate | 1990 |
| Bemat Holding AS | Health & social care | 2023 |
| Bendtsen Works AS | Administrative & support | 2026 |
| Bentzen AS | Wholesale & retail | 1995 |
| Bentzen Eiendom AS | Real estate | 1999 |
| Bentzen Invest AS | Wholesale & retail | 2005 |
| Bentzen Moss Begravelsesbyrå AS | Other services | 1975 |
| Bepe Trading AS | Wholesale & retail | 1999 |
| Berg Holding HB AS | | 2025 |
| Berg Holding HR Datter AS | | 2024 |
| Berg Holding RB AS | | 2025 |
| Berg Landskap Og Design AS | Professional & scientific | 1987 |
| Berg Property Management AS | Real estate | 2006 |
| Bergroth Holding AS | Arts & recreation | 2019 |
| Berntzen Gode Råd AS | Professional & scientific | 2020 |
| Berry Norway Containers AS | Manufacturing | 2023 |
| Bertmark Norge Holding AS | Information & communication | 2010 |
| Best 101 AS | Transport & logistics | 2022 |
| Best Rek.No AS | Wholesale & retail | 2020 |
| Betamo AS | Wholesale & retail | 1996 |
| Betamo Eiendom AS | Real estate | 2011 |
| Betterness AS | Professional & scientific | 2019 |
| Beyer-Olsen Invest AS | Financial services | 2011 |
| Bfab Norge AS | Transport & logistics | 1992 |
| BG Sivilingeniør AS | Professional & scientific | 2023 |
| BG Vault AS | | 2017 |
| Bialon Bygg Team AS | Construction | 2019 |
| Bifferiet AS | Hospitality | 2021 |
| Bil Og Maskintransport AS | Transport & logistics | 2013 |
| Bilartikler Moss Sternfoss & Sternfoss Da | Wholesale & retail | 1995 |
| Bilbutikk 1 AS | Other services | 1998 |
| Bilco Norge AS | Wholesale & retail | 2014 |
| Billigkroken AS | Wholesale & retail | 2023 |