| 3-BYGG Østfold AS | Wholesale & retail | 2009 |
| 4L Utvikling AS | Real estate | 2014 |
| 5B Prosjekt AS | Real estate | 2007 |
| A&I Gruppen AS | Construction | 2022 |
| A&I Maskinutleie AS | Construction | 2024 |
| A. Ådalen AB | Professional & scientific | 2025 |
| Abc Elektro Team AS | Construction | 2002 |
| Abc Regnskapspartner AS | Professional & scientific | 2026 |
| Across Borders & Co AS | Administrative & support | 2017 |
| Advokathuset Justisia AS | Professional & scientific | 2019 |
| Airon AS | Construction | 2019 |
| Airon AS | Construction | 2026 |
| Aktiv Lykke AS | Education | 2013 |
| Almu AS | Real estate | 2021 |
| Amax Invest AS | | 2024 |
| Amnoda Helse AS | Health & social care | 2010 |
| Andersen Process Consulting AS | Professional & scientific | 2007 |
| Anlegg & Infrastruktur AS | Construction | 2020 |
| Appelx AS | Information & communication | 2014 |
| Arbeidskraft Solution AS | Administrative & support | 2024 |
| Arne Stangebyes Gate 8 AS | Real estate | 2020 |
| AS Borg Fagmaling | Construction | 1978 |
| AS Betongbygg | Construction | 1981 |
| AS Rolv Holstad | Wholesale & retail | 1981 |
| AS West-Land | Real estate | 1989 |
| Asco AS | Construction | 1990 |
| Asco Eiendom AS | Real estate | 1984 |
| Assetbuddy AS | Information & communication | 2026 |
| Astra Tannklinikk AS | Health & social care | 2025 |
| At Prosjekt AS | Professional & scientific | 2021 |
| Atillitum AS | Wholesale & retail | 1998 |
| Aujid AS | Information & communication | 2023 |
| Ava Økonomi AS | Professional & scientific | 2022 |
| Axes AS | Professional & scientific | 2012 |
| Axes Eiendom AS | Real estate | 2020 |
| B.B Holding AS | | 2025 |
| Bagn Eiendom AS | Real estate | 2008 |
| Barentsfisk Ans | Wholesale & retail | 1989 |
| Be-Pe Klær AS | Wholesale & retail | 2025 |
| Beekeepers Chemicals AS | Wholesale & retail | 2024 |
| Beinrangel AS | Professional & scientific | 2024 |
| Betongbygg Bolig AS | Real estate | 2020 |
| Betongbygg Gruppen AS | Construction | 2020 |
| Betongbygg Næring AS | Real estate | 2020 |
| Betonmast Østfold AS | Construction | 2008 |
| BF Drift Christianslund AS | Wholesale & retail | 2013 |
| BF Drift Lande AS | Wholesale & retail | 2019 |
| BF Drift Tista AS | Wholesale & retail | 2012 |
| BG Lifeline Investment AS | Wholesale & retail | 2025 |
| Bjørge Invest AS | | 2020 |
| Bjørge-Eiendom AS | Real estate | 2021 |
| Bjørnstadmyra 12 AS | Real estate | 2011 |
| Bjørnstadmyra 4 AS | Real estate | 2017 |
| Bjørnstadmyra 6 AS | Real estate | 2017 |
| Bjørnstadmyra 7A AS | Real estate | 2019 |
| Bjørnstadveien 1 AS | Real estate | 2014 |
| Bjørnstadveien 50 a AS | Real estate | 2013 |
| Bjørnstadveien 50 B AS | Real estate | 2013 |
| Bjørnstadveien 50 C AS | Real estate | 2013 |
| Blakkestad Aslaksen Holding AS | Professional & scientific | 2025 |
| Bobilglede AS | Wholesale & retail | 2003 |
| Bokon AS | Professional & scientific | 2021 |
| Bolig-Glede AS | Real estate | 2024 |
| Borg Asfalt AS | Construction | 2015 |
| Borg Drift & Eiendom AS | Real estate | 2004 |
| Borg Renhold AS | Administrative & support | 2015 |
| Borgås Holding AS | | 2022 |
| BP Eiendom AS | Real estate | 1987 |
| Bralu Holding AS | Professional & scientific | 2023 |
| Bralu Invent AS | Professional & scientific | 2024 |
| Brandsafe AS | Information & communication | 2011 |
| Brautaset Invest AS | | 2025 |
| Brenntag Nordic AS | Wholesale & retail | 1985 |
| Brick AS | Professional & scientific | 2001 |
| Brick Eiendom AS | Real estate | 2014 |
| Brødrene Bjørge Holding AS | Professional & scientific | 2015 |
| BS Hestesenter AS | Agriculture & fishing | 2005 |
| Bsa Betongvare AS | Wholesale & retail | 2022 |
| Butterfly Bakeri Og Konditori AS | Manufacturing | 1987 |
| Bygg Østfold AS | Construction | 2021 |
| Byhaven Sarpsborg AS | Real estate | 2016 |
| Bywe AS | Wholesale & retail | 2001 |
| Betongbygg Eiendom AS | Real estate | 1987 |
| C&D Holding AS | | 2023 |
| Ca Utvikling AS | Real estate | 2014 |
| Calib Capital AS | | 2024 |
| Capitech AS | Information & communication | 2012 |
| Carbon Centric AS | Manufacturing | 2021 |
| Center Revisjon AS | Professional & scientific | 2016 |
| Center-Revisjon Holding AS | Professional & scientific | 2005 |
| Champion Idrettsmassasje & Trening AS | Health & social care | 2025 |
| Che Holding AS | | 2022 |
| Check Accounting AS | Professional & scientific | 2020 |
| Check AS | Information & communication | 2026 |
| Check Equity AS | | 2025 |
| Chrisko AS | | 2010 |
| Cibe AS | Real estate | 2021 |
| Colligo AS | Real estate | 2019 |
| Colligo Drift & Utvikling AS | Real estate | 1989 |
| D:Signage AS | Information & communication | 2022 |