| Bul Bygg AS | Drammen | 2017 |
| Bula Eiendom AS | Austafjord | 2015 |
| Bulk Data Centers N01 Power AS | Oslo | 2016 |
| Bulk Powered Land AS | Oslo | 2016 |
| Bulkteknik Sweden AB | 531 30 Lidköping | 2010 |
| Bull Betongpumping AS | Oppaker | 2020 |
| Bulldozer Maskinlag Entreprenør AS | Sortland | 1997 |
| Bullerbekämparen Svenska Aktiebolag | Se 443 61 Stenkullen | 2021 |
| Bulling AS | Skui | 2015 |
| Bulls AS | Malvik | 1996 |
| Bulls Eiendom AS | Malvik | 2013 |
| Bulls Holding AS | Malvik | 2005 |
| Bulmak AS | Oslo | 2012 |
| Bulycke Enginering Dahlberg | Lørenskog | 2002 |
| Bulæg AS | Borhaug | 2021 |
| Buma AS | Fjerdingby | 2017 |
| Bundebygg AS | Oslo | 1991 |
| Bundegruppen AS | Oslo | 1997 |
| Bunes Maskin AS | Gardvik | 2023 |
| Bunor AS | Grimstad | 2020 |
| Bunor Holding AS | Grimstad | 2020 |
| Buraas Bygg AS | Fjellhamar | 2020 |
| Burandt Byggservice AS | Greåker | 2011 |
| Burmeister & Wain Scandinavian Contractor | Dk-3450 Allerød | 2019 |
| Burtix AS | Skjeberg | 2024 |
| Busengdal AS | Stordal | 1984 |
| Busengdal Entreprenør AS | Stordal | 2019 |
| Busengdal Maskiner AS | Stordal | 2026 |
| Bushra Bygg Og Maling AS | Oslo | 2025 |
| Busken Rør Da | Solbergmoen | 1997 |
| Buskerud & Vestfold Fyringsservice AS | Steinsholt | 2012 |
| Buskerud Bad & Rørservice AS | Hønefoss | 2022 |
| Buskerud Betong Bygg AS | Vestfossen | 2012 |
| Buskerud Betongarmering AS | Krokstadelva | 2012 |
| Buskerud Blikk & Montasje AS | Drammen | 2002 |
| Buskerud Blikk & Sveis AS | Drammen | 1993 |
| Buskerud Blikk Bærum AS | Skui | 2023 |
| Buskerud Blikk Holding AS | Drammen | 2005 |
| Buskerud Brannsikring AS | Skollenborg | 2014 |
| Buskerud Bygg & Elektro AS | Vikersund | 2012 |
| Buskerud Bygg AS | Vikersund | 2025 |
| Buskerud Bygg Og Eiendom AS | Krokstadelva | 2022 |
| Buskerud Dykkerservice AS | Kongsberg | 2018 |
| Buskerud Elektro AS | Asker | 2017 |
| Buskerud Gjenvinning AS | Hokksund | 2001 |
| Buskerud Inneklima AS | Hokksund | 2026 |
| Buskerud Kulde AS | Hokksund | 2000 |
| Buskerud Malerforretning AS | Skollenborg | 1996 |
| Buskerud Og Vestfold Klima Og Kulde AS | Våle | 2006 |
| Buskerud Oppussing AS | Vestfossen | 2017 |
| Buskerud Rør & Flis AS | Skollenborg | 2012 |
| Buskerud Snekker AS | Drammen | 2024 |
| Buskerud Snekkerservice AS | Hønefoss | 2018 |
| Buskerud Solskjerming AS | Hønefoss | 2025 |
| Buskerud Sprenging Og Graving AS | Mjøndalen | 2008 |
| Buskerud Tak AS | Krokstadelva | 2025 |
| Buskerud Tak Og Blikk AS | Mjøndalen | 2021 |
| Buskerud Tak Og Bygg AS | Kongsberg | 2026 |
| Buskerud Takpartner AS | Krokstadelva | 2024 |
| Buskerud Utemiljø AS | Drammen | 2025 |
| Buskerud Va AS | Skollenborg | 2020 |
| Buskerud Vann Og Ventilasjon AS | Lier | 2014 |
| Buskerud Varmepumpeservice AS | Drammen | 2008 |
| Buskerud Veivedlikehold AS | Skollenborg | 2018 |
| Buskerud-Vestfold Kjøleservice AS | Hokksund | 2026 |
| Buso Tech | Lv-3017 Jelgavas Nov | 2023 |
| Busolar AS | Kleppe | 2005 |
| Bustadhus AS | Halden | 2016 |
| Bustnes Bygg AS | Mo I Rana | 2024 |
| Busy AS | Drammen | 2013 |
| Butec Da | Straume | 2007 |
| Butikkhusgården Bygg AS | Kristiansand S | 2007 |
| Butikkmontasje AS | Kongsvinger | 2010 |
| Butikkprosjekt AS | Oslo | 2020 |
| Butiksgruppen (Filial, No) Nuf | Se-302 41 Halmstad | 2022 |
| Butler Holding AS | Hvam | 2020 |
| Butzbach GmbH Industrietore | De-89293 Kellmünz | 2015 |
| Buvik Elektro AS | Trondheim | 1987 |
| BV Bygg AS | Eidsvåg I Åsane | 2017 |
| BV Bygg Prosjekt AS | Oslo | 2025 |
| BVD Bygg AS | Fredrikstad | 2026 |
| BVH Bygg AS | Birkeland | 2020 |
| BVS Blikkenslagerservice AS | Skotselv | 2006 |
| BVS Klima Og Rør AS | Tvedestrand | 2021 |
| BVT AS | Randaberg | 1999 |
| BW Betonggulv AS | Vågå | 2023 |
| BW Elbemanning Da | Skjetten | 2010 |
| BW Entreprenør AS | Melhus | 2025 |
| BW VVS & Bygg AS | Oslo | 2026 |
| BWG Homes AS | Oslo | 2005 |
| BWS Holding AS | Tønsberg | 2004 |
| BWT Birger Christensen AS | Asker | 1962 |
| By & Bo AS | Haugesund | 2013 |
| By Bjørkheim AS | Oslo | 2013 |
| By Bygg Verdal AS | Verdal | 2017 |
| By Entreprenør AS | Skaun | 2017 |
| By Landbruk & Maskinlag AS | Åfjord | 2016 |
| By Lmo AS | Tranby | 2021 |
| By Og Bygd AS | Vikersund | 2021 |
| By Ted AS | Oslo | 2021 |