| Barnehagenett AS | Professional & scientific | 2010 |
| Barny AS | Wholesale & retail | 1997 |
| Bas Arkitekter AS | Professional & scientific | 2001 |
| Baysni Medical AS | Health & social care | 2012 |
| BB Invest Holding AS | | 2025 |
| Be Finans Limited Nuf | | 2007 |
| Bedriftskonsulent CH AS | Professional & scientific | 2021 |
| Begravelsesbyrået Borg AS | Other services | 2022 |
| Benson AS | Information & communication | 2017 |
| Berak Holding AS | Wholesale & retail | 2011 |
| Bergbygården Ans | Real estate | 2007 |
| Bergsvingen Barnehage SA | Education | 1989 |
| Berna Sy & Fashion AS | Other services | 2022 |
| Bernina Nordic Norge AS | Wholesale & retail | 2011 |
| Beton AS | | 2020 |
| Between the Bun's AS | Hospitality | 2024 |
| Bikelife Norge Ans | Information & communication | 2021 |
| Bil Auto AS | Wholesale & retail | 2024 |
| Bilgarasjen Sarpsborg AS | Wholesale & retail | 2022 |
| Bilglass Service AS | Construction | 2024 |
| Bilvarehuset Østfold AS | Other services | 2009 |
| Biocorp AS | Transport & logistics | 2022 |
| Birdie Holding AS | | 2005 |
| Bjerknes Renhold & Vaktmestertjenester AS | Administrative & support | 2025 |
| Bjordal Holding and Investment AS | Health & social care | 2025 |
| Bjørge Holding AS | Real estate | 1997 |
| Bjørnstad & Josefsen AS | Administrative & support | 2017 |
| Bjørnstadmyra 9 AS | Real estate | 2011 |
| Bjørnstadmyra Eiendom AS | Real estate | 2022 |
| Bjørnstadmyra Næringseiendom AS | Real estate | 2026 |
| BK Flytt Og Pianotransport AS | Transport & logistics | 2025 |
| Blikk 1 Blikkenslagerverksted Arne Hellum AS | Construction | 1994 |
| Blikkmannen Holding AS | Real estate | 2017 |
| BM Berg Holding AS | Construction | 2005 |
| BM Byggservice Bo Martin Larsson | Construction | 2007 |
| Bn-Msp AS | Other services | 2023 |
| Bodalsjordet AS | Real estate | 2024 |
| Boglede Tune Prestegård AS | Real estate | 2021 |
| Bolig & Hytteinformasjon AS | Information & communication | 2014 |
| Boligboost AS | Real estate | 2025 |
| Bolighuset AS | Real estate | 2015 |
| Boligselskapet Oskarsgate 14 Og 16 AS | Households | 1956 |
| Boligselskapet Ulfhildsgt 2 AS | Households | 1955 |
| Boligutleien AS | Real estate | 2012 |
| Borg 1016 AS | Real estate | 2014 |
| Borg Bierstube AS | Hospitality | 2020 |
| Borg Bokhandel AS | Wholesale & retail | 1997 |
| Borg Brug AS | Real estate | 2000 |
| Borg Byggsystemer AS | Construction | 2009 |
| Borg Comit AS | Wholesale & retail | 2006 |
| Borg Dekksenter AS | Other services | 2025 |
| Borg Elkrafttjenester AS | Financial services | 2017 |
| Borg Finance AS | | 2025 |
| Borg Helse AS | Health & social care | 2023 |
| Borg Invest AS | | 2004 |
| Borg Legekontor Da | Health & social care | 1997 |
| Borg Marketing AS | Information & communication | 2024 |
| Borg Næring Og Eiendom AS | Construction | 1969 |
| Borg Radonsikring AS | Wholesale & retail | 2012 |
| Borg Total AS | Professional & scientific | 2025 |
| Borg Trafikkskole AS | Education | 2018 |
| Borg Ur & Gull AS | Wholesale & retail | 2003 |
| Borg Utvikling AS | Real estate | 2021 |
| Borge Handel AS | | 2005 |
| Borgen Barnehage NGH AS | Education | 2022 |
| Borgen Eiendom AS | Real estate | 2022 |
| Borgleden Pilegrimssenter AS | Administrative & support | 2020 |
| Borgvin AS | Professional & scientific | 1997 |
| Borregaard AS | Manufacturing | 2010 |
| Borregaard ASA | Manufacturing | 2012 |
| Borregård Hotelldrift AS | Hospitality | 2024 |
| BR Rør & Bad AS | Construction | 2022 |
| Braatnes AS | Real estate | 2017 |
| Brainworker AS | Professional & scientific | 2015 |
| Brandy Holding AS | Hospitality | 2020 |
| Bredmyra 8 AS | Real estate | 2021 |
| Brennes Auto AS | Other services | 1989 |
| Brennes Holding AS | Real estate | 1973 |
| Brisk Holding AS | Other services | 2021 |
| Brunch'N Ans | Hospitality | 1998 |
| Brusemyr Eiendom AS | Real estate | 2021 |
| BT Needs Da | Wholesale & retail | 2016 |
| Bukkenes Vel, Vann Og Avløpslag SA | Water & waste | 2006 |
| Business Partner AS | Professional & scientific | 2009 |
| Butikkinspirasjon AS | Wholesale & retail | 2000 |
| Bye-Gruppen AS | Real estate | 2021 |
| Byfesten Sarpsborg AS | Arts & recreation | 2024 |
| Bygaard Invest AS | Real estate | 2026 |
| Bygg Bevaring AS | Construction | 2026 |
| Bygg Og Montering Fredrikstad AS | Construction | 2023 |
| Byggmester Aage Nilsen AS | Construction | 1990 |
| Byggmester Berg AS | Construction | 1987 |
| Byggmester Kent Karlsen AS | Construction | 2014 |
| Byggtec Service Og Montasje AS | Construction | 2020 |
| Byggtekh AS | Construction | 2018 |
| Byggtiltak AS | Real estate | 2015 |
| Bård Breivik AS | Wholesale & retail | 1997 |
| Bølge Consult AS | Professional & scientific | 2025 |
| Børsand AS | Real estate | 2023 |
| C.F.G Holding AS | | 2026 |