| Anlegg Sør-Øst AS | Construction | 2026 |
| Anleggsgartner Per E. Fasting AS | Administrative & support | 2016 |
| Anleggsgartnerfirmaet Stensland Og Meum Ans | Administrative & support | 1990 |
| Anleggsgartnerfirmaet Stensland Og Meum AS | Administrative & support | 2003 |
| Annekset 2 AS | Financial services | 2005 |
| Anouska Tønsberg AS | Wholesale & retail | 2022 |
| Ans Almora Eiendom | Real estate | 1989 |
| Ans Glade Glass | | 1989 |
| Ans Øvre Langgate 44 | Real estate | 1990 |
| Ansu Holding AS | Hospitality | 2017 |
| Ansvar Invest AS | | 2025 |
| Ant SK AS | Administrative & support | 2015 |
| Anton Bussreiser AS | Transport & logistics | 2019 |
| Apeiron Holding AS | Real estate | 2006 |
| Apeiron Invest AS | Real estate | 2005 |
| Apicem AS | | 2021 |
| Apollon Tønsberg AS | Hospitality | 2021 |
| Apotekergata 20 AS | Real estate | 2013 |
| Apparent AS | Wholesale & retail | 2012 |
| Aqua Bad AS | Wholesale & retail | 2003 |
| Ar Heide Holding AS | Administrative & support | 2023 |
| Aras Frisør Tønsberg AS | Other services | 2021 |
| Arcanum Capital AS | | 2026 |
| Arcstone Engineering AS | Information & communication | 2013 |
| Arctic Flavors AS | Hospitality | 2024 |
| Arctic Home AS | Wholesale & retail | 2022 |
| Arctic Klima System AS | Construction | 2022 |
| Arctic Subsea AS | Professional & scientific | 2009 |
| ARCTICSOURCE1 AS | Wholesale & retail | 2010 |
| Arendal Torvet 3 AS | Real estate | 2017 |
| Ariemi Eiendom AS | Real estate | 2023 |
| Ariemi Holding AS | Real estate | 2021 |
| Ariris AS | | 2026 |
| Ark-Tellus AS | Professional & scientific | 2011 |
| Arkitektur I Skolen Da | Education | 2008 |
| Armerina AS | Real estate | 2005 |
| Arnosta Nuf | Administrative & support | 2024 |
| Arons AS | Wholesale & retail | 2005 |
| Arrk AS | Administrative & support | 2019 |
| Art Garden Næring AS | Real estate | 2023 |
| Arthurson Step-In AS | Transport & logistics | 2023 |
| Aru Eiendom Da | Real estate | 2003 |
| Arvid Thoresen Båtkalesjer AS | Manufacturing | 2002 |
| AS Adamas | Manufacturing | 2020 |
| AS Andersen Eiendomsselskap | Real estate | 1975 |
| AS Bergan & Søn | Real estate | 1987 |
| AS F a Bugge | Real estate | 1967 |
| AS Møllegaten 4 | Wholesale & retail | 1962 |
| AS Servitek | Manufacturing | 2019 |
| AS Storgt 39 | Real estate | 1913 |
| AS Strandgården | Households | 1957 |
| AS Trudvang Terrasse a 2 | Households | 1966 |
| AS Trudvang Terrasse A 3 | Households | 1971 |
| AS Vidars | Wholesale & retail | 1985 |
| Asclepius Eiendom AS | Real estate | 2022 |
| Asekom AS | Financial services | 2016 |
| Aset Holding AS | Wholesale & retail | 2014 |
| Asiahallen Frukt & Grønt AS | Wholesale & retail | 2019 |
| Asian Fortune AS | Hospitality | 2025 |
| Asl Consulting AS | Professional & scientific | 2017 |
| Asmild AS | Arts & recreation | 2015 |
| Aso Holding AS | Real estate | 2005 |
| Aso Management AS | Professional & scientific | 1981 |
| Aso Utvikling AS | Real estate | 2016 |
| Asp Gruppen AS | Administrative & support | 2000 |
| Aspava AS | Health & social care | 1986 |
| Aspava Invest AS | Health & social care | 2005 |
| Asplin AS | Financial services | 2006 |
| Assegai AS | Health & social care | 2014 |
| Astou Yoga AS | Education | 2019 |
| Athenas AS | Professional & scientific | 2010 |
| Athwal Invest AS | Construction | 2011 |
| Atk Consulting AS | Professional & scientific | 2025 |
| Atlant Eiendom AS | Real estate | 2013 |
| Atlant Entreprenør AS | Construction | 2016 |
| Atlant Gruppen AS | Construction | 2016 |
| Atlanti AS | | 2021 |
| Ator Labs AS | Information & communication | 2023 |
| Attachè Kommunikasjon AS | Professional & scientific | 2015 |
| Attic Forest AS | Transport & logistics | 1994 |
| Atum Økonomi AS | Financial services | 2015 |
| Auganes Realinvest AS | Real estate | 2005 |
| Aukland Coaching AS | Arts & recreation | 2016 |
| Aura Salong AS | Other services | 2025 |
| Aureus Diving AS | Construction | 2016 |
| Aurora Senteret AS | Other services | 2000 |
| Auroraa.Beautyyy AS | Other services | 2025 |
| Autic Invest AS | Wholesale & retail | 2005 |
| Autic System AS | Wholesale & retail | 1994 |
| Autoclassic Togbutikken AS | Wholesale & retail | 2012 |
| Automation of Things AS | Professional & scientific | 2017 |
| Autor AS | Wholesale & retail | 2020 |
| Autospesialisten Eiendom AS | Other services | 2017 |
| Autospesialisten Holding AS | Other services | 2017 |
| Autospesialisten Tønsberg AS | Other services | 2017 |
| Autostrada Tønsberg AS | Wholesale & retail | 2017 |
| Av Byggservice AS | Construction | 2021 |
| Avanoq AS | Information & communication | 2026 |
| Avarius AS | | 2018 |
| Avarn Security Service AS | Administrative & support | 2013 |