| Araz Bilopphugging Da | Wholesale & retail | 2009 |
| Arbor Helse AS | Health & social care | 2025 |
| Arcadis Norway AS | Professional & scientific | 2023 |
| Arcads Ans | Professional & scientific | 2025 |
| Arctic Wearbox AS | Administrative & support | 2026 |
| Are Haugen AS | Real estate | 2006 |
| Arema AS | Transport & logistics | 2005 |
| Argenti Eiendom AS | Real estate | 2005 |
| Argentum Regnskap Og Finans AS | Professional & scientific | 1995 |
| Argus AS | Health & social care | 2000 |
| Ari Eiendom AS | Construction | 2014 |
| Ari Holding AS | | 2014 |
| Ariana Bilpleie AS | Other services | 2012 |
| Ark Bolig Telemark AS | Real estate | 2021 |
| Ark Eiendom Telemark AS | Real estate | 2016 |
| Ark Royal AS | Financial services | 2002 |
| Arkaden Fysioterapi AS | Health & social care | 2018 |
| Arkitektkontoret Henning Karlsen AS | Professional & scientific | 1999 |
| Arkitektkontoret Morten Jahren AS | Professional & scientific | 2010 |
| Arkorib AS | Professional & scientific | 2026 |
| Arne Thorsen Holding AS | Real estate | 2001 |
| Arnestad Drift AS | Construction | 2018 |
| Arnestad Enterprise AS | Construction | 2018 |
| Arnestad Holding AS | Manufacturing | 2017 |
| Arnold Rønningen Holding AS | Wholesale & retail | 2005 |
| Aron Holding AS | Construction | 2018 |
| Arro Invest AS | Real estate | 1997 |
| Art Group AS | Real estate | 1998 |
| Arta Eiendom Ans | Real estate | 2004 |
| ARTHUR SVENDSENS EFTF AS Rolf Svendsen og Sønner | Real estate | 1987 |
| Artin Piping AS | Professional & scientific | 2012 |
| Arvesen Bygg AS | Construction | 2015 |
| AS Borgeåsen | Real estate | 1967 |
| AS Dameco | Manufacturing | 1985 |
| AS Herdebred | Financial services | 1915 |
| AS Maskin Consult | Wholesale & retail | 1982 |
| AS Mælagt 3 | Real estate | 1977 |
| AS Odds Stadion | Arts & recreation | 1920 |
| AS Torggaten 18 | Real estate | 1926 |
| AS Varden | Information & communication | 1918 |
| Asap Media AS | Manufacturing | 2022 |
| Asap-Norway AS | Manufacturing | 2007 |
| Asb Eiendom 2 AS | Real estate | 2023 |
| Asb Eiendom AS | Real estate | 2011 |
| Asbjørn Goberg AS | Wholesale & retail | 1978 |
| Asbjørn Vaa Transport AS | Transport & logistics | 2014 |
| Asbjørnsens Gate 11 AS | Real estate | 2025 |
| Aschehoug Invest & Consulting AS | Real estate | 2024 |
| Asfaltknut AS | Professional & scientific | 2024 |
| Asfaltleggeren AS | Construction | 2021 |
| Askedalen Gård AS | Agriculture & fishing | 2025 |
| Askøy Bygg Og Industri AS | Construction | 2014 |
| Assetto AS | Professional & scientific | 2021 |
| Atag AS | Construction | 2026 |
| Atlas Frisk AS | Transport & logistics | 2025 |
| Atle Bringsås AS | Agriculture & fishing | 2009 |
| Aubert Invest AS | | 1990 |
| Audiopol Da | Arts & recreation | 1997 |
| Audiopol Live Da | Administrative & support | 2007 |
| Auestadmeland Holding AS | Health & social care | 2015 |
| Augestad Holding AS | | 2021 |
| Augonsplassen AS | Real estate | 2018 |
| Austad Bilpleie AS | Other services | 2022 |
| Auto 1 Bil AS | Wholesale & retail | 2019 |
| Auto 1 Skien AS | Other services | 2010 |
| Auto Trimmer AS | Professional & scientific | 2021 |
| AUTO365 AS | Wholesale & retail | 2022 |
| Autoama AS | Wholesale & retail | 2021 |
| Autobilsenter AS | Wholesale & retail | 2026 |
| Autobudget AS | Wholesale & retail | 2015 |
| Autobudget Service AS | Other services | 2019 |
| Autoby AS | Wholesale & retail | 2023 |
| Autoforia AS | Wholesale & retail | 2020 |
| Autoforum AS | Wholesale & retail | 2024 |
| Autogarden AS | Wholesale & retail | 2018 |
| Autohuset Grenland AS | Wholesale & retail | 2017 |
| Autolab AS | Professional & scientific | 2026 |
| Autoland Bil AS | Wholesale & retail | 2022 |
| Automobile AS | Wholesale & retail | 2021 |
| Automotor AS | Wholesale & retail | 2022 |
| Autonoa AS | Wholesale & retail | 2023 |
| Autotech Skien AS | Other services | 2005 |
| Avakar Holding AS | | 2021 |
| Avehus AS | Real estate | 2013 |
| Avilla Invest AS | | 2026 |
| Avinxt AS | Professional & scientific | 2016 |
| Avinxt Defence AS | Professional & scientific | 2021 |
| Axb Holding AS | Financial services | 2016 |
| Aya Kapital AS | | 2024 |
| Az Entropy AS | Professional & scientific | 2024 |
| Az Transport AS | Transport & logistics | 2025 |
| Arne Thorsen Eiendom A/S | Real estate | 1986 |
| Arne Thorsen Spedisjon A/S | Transport & logistics | 1986 |
| Arne Thorsen Transport A/S | Transport & logistics | 1976 |
| B Bygg & Flis AS | Construction | 2015 |
| B Grande Holding AS | Financial services | 2005 |
| B Sveinsson AS | Construction | 2015 |
| B&B Stillasutleie Grenland AS | Administrative & support | 2020 |
| B-A Rekruttering AS | Administrative & support | 2015 |
| B-Torvund AS | Real estate | 2012 |