| Aarnæs & Andersen Kjøtt Ans | Manufacturing | 1989 |
| Aars AS | Other services | 2009 |
| Aars Invest AS | Construction | 1995 |
| Aarseth Invest AS | | 2019 |
| Aarsrud Bygg AS | Construction | 2023 |
| Aarstein Invest AS | Financial services | 2014 |
| Aarsverk AS | Professional & scientific | 2021 |
| Aart | Professional & scientific | 2010 |
| Aart Architects No AS | Professional & scientific | 1997 |
| Aarum Teglverk AS | Real estate | 1925 |
| Aarum Teglverk Utvikling AS | Real estate | 2012 |
| Aarvåg-Amundsen Holding AS | | 2022 |
| Aas Forvaltning AS | | 2026 |
| Aas Invest Holding AS | | 2020 |
| Aas Tech AS | | 2022 |
| Aasaaren Esg AS | | 2023 |
| Aasaveien 1 AS | Households | 1923 |
| Aasbryn Holding AS | | 2026 |
| Aasc Gruppen AS | Wholesale & retail | 2024 |
| Aase AS | | 2026 |
| Aase Eiendom AS | Real estate | 1988 |
| Aase Gaard AS | Real estate | 2006 |
| Aase Gaustad Invest AS | | 2023 |
| Aase Gruppen AS | Professional & scientific | 2020 |
| Aase Prosjekt AS | Professional & scientific | 2006 |
| Aase Stemmen AS | | 2024 |
| Aase Teknikk AS | Professional & scientific | 2019 |
| Aase Utvikling AS | Professional & scientific | 2016 |
| Aaselind AS | Professional & scientific | 2022 |
| Aaselind Holding AS | Professional & scientific | 2022 |
| Aasen Eigedom 1 AS | Real estate | 2021 |
| Aasen Holding AS | | 2006 |
| Aasendesign AS | Information & communication | 2022 |
| Aases Fotterapi AS | Health & social care | 2019 |
| Aaset AS | Financial services | 2018 |
| Aasgaard Invest AS | Hospitality | 2018 |
| Aasgard Invest AS | Financial services | 2020 |
| Aasjord Madsen AS | | 2026 |
| Aasland AS | Professional & scientific | 2019 |
| Aaslund Coaching AS | Arts & recreation | 2018 |
| Aasn Holding AS | | 2022 |
| Aass Trading AS | Professional & scientific | 1961 |
| Aasta Frisør AS | Other services | 2005 |
| Aasta Hansteens Vei 3 AS | Real estate | 2020 |
| Aastad Consulting AS | Professional & scientific | 2005 |
| Aastad Holding AS | Construction | 2008 |
| Aat Holding AS | | 2018 |
| Aat Invest AS | Financial services | 2006 |
| Aata AS | Professional & scientific | 2017 |
| Aate AS | Wholesale & retail | 2025 |
| Aavik Consulting AS | Professional & scientific | 2025 |
| AB Byggplan AS | Construction | 2021 |
| AB Energiforvaltning AS | Professional & scientific | 2005 |
| AB Extra AS | Professional & scientific | 1993 |
| AB Håndverker AS | Construction | 2025 |
| AB Invest Norway AS | Hospitality | 2024 |
| AB Kapital AS | Professional & scientific | 1985 |
| AB Liftutleie AS | Administrative & support | 1994 |
| AB Mjällby Målning & BL V/Pwc Skatterådgivere AS | Administrative & support | 2011 |
| AB Sciex AS | Wholesale & retail | 2008 |
| AB Sciex LP | Professional & scientific | 2010 |
| AB Sciex Pte.Ltd | Professional & scientific | 2010 |
| AB Taksering Og Eiendom AS | Real estate | 2005 |
| AB Teknisk Overvåking Da | Construction | 1992 |
| AB Tingstad Papper | Wholesale & retail | 2006 |
| AB Traders Import & Eksport Ans | Wholesale & retail | 1990 |
| AB Trafikksenter AS | Education | 2009 |
| AB Trebolit | Wholesale & retail | 2007 |
| AB Volvo Penta | Wholesale & retail | 2002 |
| Ab-Invest AS | Real estate | 1986 |
| Ab.No Da | Professional & scientific | 2000 |
| Aba Elektro AS | Construction | 1988 |
| Aba Taxi AS | Transport & logistics | 2021 |
| Aba Transport AS | Transport & logistics | 2003 |
| Abaco Holding AS | | 2024 |
| Abaco Shipping AS | Transport & logistics | 2005 |
| Abacom AS | Administrative & support | 1995 |
| Abacos Consulting AS | Information & communication | 2006 |
| Abadjom AS | Professional & scientific | 2004 |
| Abakken AS | Real estate | 2022 |
| Abakus Invest AS | Professional & scientific | 2014 |
| Abam Holding AS | Real estate | 2025 |
| Aban Media Ans | Professional & scientific | 2001 |
| Abate AS | Wholesale & retail | 2016 |
| Abazi Holding AS | Construction | 2018 |
| Abbadi Holding AS | Manufacturing | 2021 |
| Abbadii AS | Transport & logistics | 2024 |
| Abbas Eiendom AS | Real estate | 2013 |
| Abbas Gruppen AS | Hospitality | 2015 |
| Abbas Holding AS | Real estate | 2012 |
| Abbas Investment AS | | 2025 |
| Abbasi Transport AS | Transport & logistics | 2025 |
| Abbott Diagnostics Technologies AS | Manufacturing | 1999 |
| Abbott Nordics Holding AS | | 2022 |
| Abbott Nordics Subsidiary AS | | 2022 |
| Abbott Rapid Diagnostics AS | Wholesale & retail | 1962 |
| Abbou Capital AS | | 2019 |
| Abbvie AS | Wholesale & retail | 2012 |
| Abc & Ak Holding AS | Professional & scientific | 2022 |
| Abc Accounting AS | Professional & scientific | 2014 |