| 1KRM AS | Health & social care | 2014 |
| 2 Frisører AS | Other services | 2008 |
| 3,14 Holding AS | | 2019 |
| A-B Hestetransport Invest Limited Nuf | | 2025 |
| A-B Hestetransport Limited Nuf | Transport & logistics | 2025 |
| Aae Holding AS | Financial services | 2015 |
| Aandstad Invest AS | Administrative & support | 2021 |
| Abacus Eiendom AS | Professional & scientific | 2005 |
| Abacus Holding AS | Professional & scientific | 2005 |
| Abacus Økonomitjenester AS | Professional & scientific | 2000 |
| Adam's Caravan AS | Other services | 2019 |
| Advokatfirma Sundby Ans | Professional & scientific | 2005 |
| AG Eiendom Mysen AS | Real estate | 2005 |
| Agrolife AS | Wholesale & retail | 2019 |
| Agronorth AS | Administrative & support | 2024 |
| Aircoil AS | Wholesale & retail | 1989 |
| Akc Arkitekter AS | Professional & scientific | 1997 |
| Akerheim Eiendom AS | Real estate | 2018 |
| Aktiv Mysen Og Rakkestad AS | Real estate | 2024 |
| Allmek Deje AB | Manufacturing | 2004 |
| Allprofil AS | Manufacturing | 2009 |
| Altiett AS | Other services | 2002 |
| Altitre AS | Construction | 2016 |
| Amari AS | Education | 2022 |
| Amjo Ans | Wholesale & retail | 2005 |
| Andresen Og Grøtvedt Kioskdrift Da | Wholesale & retail | 1999 |
| Anox AS | Information & communication | 2025 |
| Anton H. Mysensgt. 1 AS | Real estate | 2005 |
| Anton Øg Holding AS | Real estate | 2020 |
| Arbida AS | Administrative & support | 2002 |
| Arild Mosbæk AS | Construction | 2012 |
| Ark Ama AS | Professional & scientific | 2000 |
| Arne Haugland AS | Health & social care | 1988 |
| Arnljot AS | | 2021 |
| AS Hamatec | Manufacturing | 2022 |
| AS Momarken Travbane | Arts & recreation | 1920 |
| AS Toca | Real estate | 1968 |
| AS Torshov Automobilhus | Real estate | 1934 |
| Aspn Automatikkspesialisten AS | Construction | 2005 |
| Atelier Nor AS | Professional & scientific | 2024 |
| Atis AS | Other services | 2022 |
| Atlantic Taxi AS | Transport & logistics | 2026 |
| Atv Motor AS | Wholesale & retail | 2022 |
| Auksjoner I Blomskog Handelsbolag | Wholesale & retail | 2006 |
| Aurum Regnskap AS | Professional & scientific | 2025 |
| Authen Equity AS | | 2026 |
| Auto Prime 1 AS | Wholesale & retail | 2021 |
| Aø Medinvest AS | | 2023 |
| Bakkeliveien 2 AS | Real estate | 2005 |
| Bakketunet Avlastning AS | Health & social care | 2014 |
| Bamsrudlåven AS | Manufacturing | 2014 |
| Bang Development AS | Wholesale & retail | 2012 |
| Bauta Områdesikring AS | Administrative & support | 2018 |
| BB Mote AS | Wholesale & retail | 2020 |
| Befabulous AS | Other services | 2014 |
| Bendik Johnsen Molland Holding AS | | 2018 |
| Bent Lundsrud AS | Administrative & support | 1994 |
| Berg Fra Mysen AS | Financial services | 2016 |
| Bergerkrysset Auto Mysen AS | Other services | 1991 |
| Bergerkrysset Eiendom AS | Real estate | 1991 |
| Bergerkrysset Fritid AS | Wholesale & retail | 1976 |
| Bergland Dyreklinikk AS | Professional & scientific | 2025 |
| Bergs Matopplevelser AS | Hospitality | 2023 |
| Bergsprengning AS | Construction | 2011 |
| Bernt Bekke Arkitekter AS | Professional & scientific | 2005 |
| Bil Vulkan AS | Wholesale & retail | 1968 |
| Bilnøkkel Service Øst AS | Other services | 2026 |
| Bilteknikk Mysen AS | Other services | 2016 |
| Birkelund Eiendom AS | Real estate | 2022 |
| Blikkenslager Owrum AS | Construction | 2005 |
| Blue Seed Capital AS | Wholesale & retail | 2015 |
| Bo Ekholms Åkeri | Transport & logistics | 1996 |
| Bobil & Caravan Mysen AS | Wholesale & retail | 2025 |
| Brage Vestavik MTB Athlete AS | Arts & recreation | 2021 |
| Branka AS | Administrative & support | 2013 |
| Brannkassa Forsikring GFS | Financial services | 1896 |
| Bro Eiendom Ans | Real estate | 1992 |
| Bro Invest AS | Wholesale & retail | 1991 |
| Bråtabrann AS | Information & communication | 2023 |
| Brødremoen AS | Real estate | 2010 |
| Brødremoen Sand AS | Mining & quarrying | 1994 |
| Brødrene Mustorp Da | Agriculture & fishing | 1997 |
| Brødrene Myhrvold Transport Da | Transport & logistics | 2006 |
| BS Trafikkskole AS | Education | 2013 |
| Bundy Ans | Wholesale & retail | 2000 |
| Byggsystem Eiendom AS | Real estate | 1998 |
| Bäck & Walsøe Holding AS | Manufacturing | 2022 |
| C G Jønsson & Co AS | Real estate | 1968 |
| C.W. Korterud AS | Wholesale & retail | 1989 |
| Cantona AS | Real estate | 2016 |
| Cets Eiendom AS | Real estate | 2023 |
| Christer Lenneson | Construction | 2002 |
| Christeyns Norge AS | Wholesale & retail | 2014 |
| City Frisør Mysen AS | Other services | 2018 |
| Civas Invest AS | | 2026 |
| Clinique Belladonna AS | Other services | 2022 |
| Columbusegg AS | | 2021 |
| Compasset AS | Professional & scientific | 2008 |
| Continent Montage Aktiebolag | Construction | 1998 |
| Cora Eiendom AS | Real estate | 2023 |