| 1000 Ballonger Da | Arts & recreation | 2024 |
| 3 - Byggmester AS | Construction | 1988 |
| 3 Bygg Mester Eiendom AS | Real estate | 1996 |
| 3BM Næring AS | Real estate | 2021 |
| 3BME Holding AS | Real estate | 2020 |
| 3K Bygg AS | Professional & scientific | 2016 |
| 4FLUENT AS | Wholesale & retail | 2023 |
| 5029 Eiendom AS | Real estate | 2025 |
| 5029 Holding AS | | 2025 |
| 5029INC AS | Health & social care | 2019 |
| 5AMUNDSEN AS | Real estate | 2022 |
| A K Myromslien Bygg Service Da | Construction | 2001 |
| A to Z Bygg AS | Construction | 2020 |
| A+ Bedriftsservice AS | Administrative & support | 2020 |
| A-Aulie AS | Construction | 2013 |
| A.R.K. Bygg System AS | Construction | 2022 |
| A1 Eiendomsutvikling AS | Real estate | 2024 |
| Aaen AS | | 2019 |
| Aarvik Management AS | Professional & scientific | 1990 |
| AAS1998 AS | | 2020 |
| AB Snekkern AS | Construction | 2000 |
| Abc BHT AS | Health & social care | 2025 |
| Abc Jessheim AS | Health & social care | 2024 |
| Abc Legevakt Lillestrøm AS | Health & social care | 2025 |
| Abc Legevakt Og Legetjenester AS | Health & social care | 2022 |
| Abservice 2 AS | Wholesale & retail | 2024 |
| Abu 9 AS | Real estate | 2013 |
| Ac Homedesign AS | Professional & scientific | 2026 |
| Ac-Group Holding AS | Professional & scientific | 2020 |
| Acepilot AS | Real estate | 2020 |
| Acex AI AS | Professional & scientific | 2024 |
| Achalhi AS | | 2025 |
| Acj AS | Hospitality | 2010 |
| Active Auto AS | Wholesale & retail | 2011 |
| Acv Invest AS | Real estate | 2005 |
| Adam Frisør a AS | Other services | 2025 |
| Adam Og Eva Jessheim AS | Other services | 2013 |
| Addsecure Smart Transport Norge Nuf | Information & communication | 2011 |
| Adico Service AS | Professional & scientific | 2012 |
| Adler AS | Real estate | 1985 |
| Adora Food AS | Hospitality | 2020 |
| Adrien Mann Agenturer AS | Real estate | 2003 |
| Advia Property AS | Real estate | 2023 |
| Advokatfirmaet Sarwarson AS | Professional & scientific | 2023 |
| Afrodev AS | Information & communication | 2026 |
| Aftab AS | Real estate | 2015 |
| Aftab Equities AS | Information & communication | 2021 |
| Aftabgruppen AS | Information & communication | 2024 |
| Agat Data Ans | Wholesale & retail | 1986 |
| Ageni Invest AS | | 2020 |
| Airport Taxi AS | Transport & logistics | 2024 |
| Akera AS | Professional & scientific | 2003 |
| Akershus Bolig Og Næring AS | Real estate | 2006 |
| Akershus Entreprenør Holding AS | Administrative & support | 2012 |
| Akershus Kjøkkensenter AS | Wholesale & retail | 2020 |
| Akershus Regnskap AS | Professional & scientific | 2025 |
| Akershus Taxi Og Buss AS | Transport & logistics | 2024 |
| Akershus Vare Distribusjon Ans | Transport & logistics | 1999 |
| Akh Holding AS | Construction | 2021 |
| Akl Holding AS | Professional & scientific | 2013 |
| Ako Eiendom Ans | Real estate | 1990 |
| Akselsen Holding AS | Real estate | 2012 |
| Aktiv Livsstil AS | Education | 1995 |
| Aladdin Jessheim AS | Wholesale & retail | 2026 |
| Alfa Drive Trafikkskole AS | Education | 2026 |
| Algarheim & Fure Da | Wholesale & retail | 2001 |
| Algarheimsvegen 29 AS | Real estate | 2014 |
| Algerheim Mat AS | Wholesale & retail | 2003 |
| Alital AS | Financial services | 2010 |
| Alizadeh Invest AS | Other services | 2021 |
| Alka 515 AS | Transport & logistics | 2026 |
| Allan Holding AS | | 2022 |
| ALLE4HUS AS | Wholesale & retail | 2019 |
| Alliance Holding AS | Wholesale & retail | 2023 |
| Alt Service AS | Construction | 2020 |
| Altitude Transport AS | Transport & logistics | 2025 |
| Aluflex System AS | Wholesale & retail | 1993 |
| Am Byggkonsult AS | Professional & scientific | 2025 |
| Amazing Scandinavia AS | Administrative & support | 2025 |
| Ambasto AS | Wholesale & retail | 2019 |
| Amentox AS | Professional & scientific | 2023 |
| American Spirits & Beers AS | Wholesale & retail | 2014 |
| Amoura Da | Wholesale & retail | 2025 |
| Amraj AS | Hospitality | 2018 |
| Amundia AS | Real estate | 2021 |
| Amundia Kapital AS | Real estate | 2021 |
| Amundsen Gruppen AS | Real estate | 2017 |
| Amundsen Prosjekt AS | Professional & scientific | 2017 |
| Amyk Consult AS | Information & communication | 2021 |
| Ana AS | Health & social care | 2011 |
| Andelva Kiosk Og Gatekjøkken Ans | Hospitality | 1990 |
| Anders Helling AS | | 2024 |
| Andersen Kiropraktikk AS | Health & social care | 2007 |
| Andrè Larsen Boligutvikling AS | Construction | 2006 |
| André Holum Holding AS | | 2023 |
| Anglo-Asian Holding Ans | Real estate | 2000 |
| Anla Konsult AS | Information & communication | 2018 |
| Anliel AS | Wholesale & retail | 2005 |
| Ann Kristin Gundersen Holding AS | | 2021 |
| Anni&Co AS | Wholesale & retail | 2012 |