| Bunnpris Ugla AS | Wholesale & retail | 1984 |
| Buran Holding AS | Manufacturing | 2008 |
| Burgas Singh AS | Hospitality | 2013 |
| Burgund Holding AS | | 2019 |
| Buseth Invest AS | Financial services | 2018 |
| Business Is Fun AS | Information & communication | 2023 |
| Businisse AS | | 2023 |
| Bussto AS | Transport & logistics | 2013 |
| Bustnes AS | Information & communication | 2010 |
| Buteo AS | Real estate | 2005 |
| Butikkbygg Sørøst AS | Real estate | 2006 |
| Butikkdrift Grønskag AS | Wholesale & retail | 2024 |
| Butikkdrift Næss AS | Wholesale & retail | 2012 |
| Butikkdrift Sunniva Larsen AS | Wholesale & retail | 2023 |
| Butikkeiendom II Skjæveland AS | Real estate | 2022 |
| Butikkeiendom Skjæveland AS | Real estate | 2021 |
| Butikkutvikling Nidaros AS | Education | 2012 |
| Buvik Elektro AS | Construction | 1987 |
| Buvik Invest AS | Real estate | 2005 |
| Buvik Trafikksenter Drift AS | Wholesale & retail | 2014 |
| Buylink AS | Information & communication | 2025 |
| Buylink Holding AS | | 2025 |
| Buzzter AS | | 2020 |
| Buzzter Holding AS | | 2020 |
| Buøy Fysio- Og Treningsoppfølging AS | Health & social care | 2025 |
| BV1A AS | Real estate | 2019 |
| BV58 Holding AS | | 2025 |
| BVH AS | Hospitality | 2018 |
| BWG Holding AS | | 1999 |
| By Lager AS | Real estate | 2025 |
| By Strands Ans | Professional & scientific | 2025 |
| By Strands AS | Professional & scientific | 2026 |
| By-Holding AS | | 2024 |
| Bybroen AS | Hospitality | 2004 |
| Bybroen Bolig AS | Real estate | 1988 |
| Bybroen Holding AS | Real estate | 2005 |
| Bybroen Hørselshjelp AS | Health & social care | 1993 |
| Bybroen Utvikling AS | Real estate | 2001 |
| Bybroen Videregående Skole AS | Education | 1989 |
| Bye Acoustic Design AS | Manufacturing | 2024 |
| Byens Rørservice AS | Construction | 2011 |
| Bygg Bygg Proff AS | Real estate | 2023 |
| Bygg Consulting AS | Professional & scientific | 2025 |
| Bygg Design Trondheim AS | Construction | 2016 |
| Bygg Ide AS | Professional & scientific | 2019 |
| Bygg Og Løsøretakst AS | Professional & scientific | 2010 |
| Bygg-Tek AS | Professional & scientific | 2012 |
| Byggekunst Holding AS | Real estate | 2015 |
| Byggevare Midt-Norge AS | Wholesale & retail | 2019 |
| Byggfirma Postholm Og Nordløkken AS | Construction | 2002 |
| Byggherrerådgiveren AS | Professional & scientific | 2019 |
| Byggkompetanse Midt-Norge AS | Professional & scientific | 2009 |
| Byggkonsult AS | Professional & scientific | 1992 |
| Byggmester 1 AS | Construction | 2008 |
| Byggmester Arnt Emil Henriksen AS | Construction | 2012 |
| Byggmester Arnøy & Haugen AS | Construction | 2019 |
| Byggmester Edvardsen AS | Construction | 2024 |
| Byggmester Espen Aune AS | Construction | 2005 |
| Byggmester Grindflaten AS | Construction | 2022 |
| Byggmester H. Clausen AS | Construction | 2023 |
| Byggmester Hans Helseth AS | Construction | 1995 |
| Byggmester Herman Frost AS | Construction | 2005 |
| Byggmester Indergård Og Nypan AS | Construction | 2000 |
| Byggmester Johan Lundbo AS | Construction | 2005 |
| Byggmester Karl Bekken AS | Construction | 1992 |
| Byggmester Knudsen AS | Construction | 1999 |
| Byggmester Korsnes AS | Construction | 2019 |
| Byggmester Lund AS | Construction | 2025 |
| Byggmester Ola Ravn Hassel AS | Construction | 2020 |
| Byggmester Postholm AS | Construction | 2025 |
| Byggmester Riiber AS | Construction | 2024 |
| Byggmester Sande & Koch AS | Construction | 2023 |
| Byggmester Steinar Halvorsen AS | Construction | 2002 |
| Byggmester Ulrik Rendal AS | Construction | 2014 |
| Byggmester Vegar Ø. Sivertsen AS | Construction | 2017 |
| Byggmester Wågan AS | Construction | 2026 |
| Byggmester Øverland AS | Construction | 2017 |
| Byggopp Trøndelag - Samarbeidsorgan for Bygg- Og Anleggsteknikk AS | Education | 2025 |
| Byggpartner Utleie AS | Administrative & support | 2026 |
| Byggreal AS | Construction | 2010 |
| Byggreal Bolig AS | Real estate | 2017 |
| Byggreal Eiendom AS | Real estate | 2005 |
| Byggrehab AS | Construction | 2021 |
| Byggsoft AS | Information & communication | 2014 |
| Byggteknikk Eiendom AS | Real estate | 1998 |
| Byggteknikk Prosjekt AS | Real estate | 1951 |
| Byggteknikk Regnskap AS | Professional & scientific | 2019 |
| Byggteknikk Utvikling AS | Real estate | 2024 |
| Byggteknisk Rådgivning AS | Professional & scientific | 2007 |
| Bygning 10 AS | Real estate | 2007 |
| Bygningsvern AS | Real estate | 2005 |
| Bygulv Blomkvartalet AS | Real estate | 2024 |
| Bygulv Sorgenfri AS | Real estate | 2022 |
| Bygården Kongensgate 41 AS | Wholesale & retail | 2017 |
| Byhaven AS | Real estate | 1989 |
| Byk Forvaltning AS | Real estate | 2025 |
| Bylivsutvikling AS | Professional & scientific | 2016 |
| Bylundvegen 62-64 AS | Real estate | 2025 |
| Bymarka Industri AS | Professional & scientific | 2024 |
| Byndle AS | Information & communication | 2014 |