| Advokatfirmaet Nidaros Inkasso Ans | Administrative & support | 2009 |
| Advokatfirmaet Pilar AS | Professional & scientific | 2021 |
| Advokatfirmaet RPB AS | Professional & scientific | 2025 |
| Advokatfirmaet Simonsen Vogt Wiig Trondheim AS | Professional & scientific | 2003 |
| Advokatfirmaet Strand & Co Ans | Professional & scientific | 1998 |
| Advokatfirmaet Wergeland AS | Professional & scientific | 2021 |
| Advokatgården Munkegaten Da | Professional & scientific | 2004 |
| Advokathuset Trondheim Da | Professional & scientific | 2002 |
| Advokatkontoret Nordenfjeldske AS | Professional & scientific | 2018 |
| Advokatnett SA | Professional & scientific | 2006 |
| Ae Developments AS | Financial services | 2008 |
| Ae Henriksen Holding AS | | 2024 |
| Aeg Holding AS | | 2024 |
| Aek Holding AS | Construction | 2014 |
| Aelo AS | Real estate | 2020 |
| Aeria AS | Professional & scientific | 2016 |
| Aether Holding AS | Professional & scientific | 2025 |
| Aett AS | Information & communication | 2026 |
| Affector AS | Professional & scientific | 2007 |
| Aflekt AS | | 2026 |
| Afro Hair Shop AS | Other services | 2024 |
| Afs Holding AS | Real estate | 2019 |
| Afw Holding AS | | 2024 |
| Afw Invest AS | | 2026 |
| AG Investor AS | Real estate | 2005 |
| Aga-B Holding AS | Construction | 2006 |
| Agathe Studio AS | Other services | 2024 |
| Agato AS | Financial services | 2005 |
| Agaton Sax AS | Other services | 1990 |
| Agdars Sportsfiske AS | Wholesale & retail | 2000 |
| Age Holding AS | Financial services | 2006 |
| Agenda Eiendom AS | Real estate | 2001 |
| Agendi AS | Construction | 2019 |
| Agenta AS | Professional & scientific | 2013 |
| Ager Holding AS | | 2024 |
| Agil Flis & Mur AS | Construction | 2021 |
| Agl Holding AS | Real estate | 2021 |
| Agnarock & Myrull AS | Professional & scientific | 2022 |
| Agr Holding AS | Real estate | 2012 |
| Agraff Arkitektur AS | Professional & scientific | 2000 |
| AGV5 AS | Real estate | 2019 |
| Agw Forvaltning AS | Real estate | 2025 |
| Agw Holding AS | | 2016 |
| Ah-Holding AS | Wholesale & retail | 2010 |
| AHA - Arkitektene Hilde og Andersen AS | Professional & scientific | 1996 |
| Aha Eiendom AS | Real estate | 2010 |
| Ahead Management AS | Professional & scientific | 2023 |
| Ahf Eiendom AS | Health & social care | 2013 |
| AHV15 AS | Real estate | 2020 |
| AHV7 Vigtil Terrasse AS | Real estate | 2016 |
| AHV8 AS | Real estate | 2019 |
| AHV9 Vigtil Terrasse AS | Real estate | 2016 |
| Aiavisen AS | Information & communication | 2026 |
| Aible AS | Information & communication | 2021 |
| Aidalos AS | Professional & scientific | 2024 |
| Aidcom Holding AS | Information & communication | 2008 |
| Aidiom 1 AS | | 2019 |
| Aidiom 2 AS | | 2019 |
| Aidiom 3 AS | | 2020 |
| Aidiom 4 AS | | 2020 |
| Aidiom 5 AS | | 2021 |
| Aidiom 6 AS | | 2021 |
| Aidiom AS | | 2019 |
| Aigery AS | Professional & scientific | 2024 |
| Aigery Mounting AS | Professional & scientific | 2025 |
| Aiie Invest AS | | 1995 |
| Aileen Invest AS | | 2022 |
| Ailo Aasen Holding AS | | 2026 |
| Ailo Productions AS | Information & communication | 2024 |
| Aimses AS | Professional & scientific | 2024 |
| Ainel Holding AS | | 2023 |
| Aiq AS | Information & communication | 2025 |
| Aiscandic AS | Transport & logistics | 2024 |
| Aiutrix AS | Information & communication | 2018 |
| Ajensen Holding AS | | 2024 |
| Ajjf Singh Holding AS | Hospitality | 2021 |
| Ajk Holding AS | Real estate | 2005 |
| Ajw Holding AS | | 2023 |
| Ak Velvære AS | Other services | 2019 |
| Aka Telecom AS | Information & communication | 2013 |
| Akath Holding AS | | 2021 |
| Akba Invest AS | Professional & scientific | 2020 |
| Aker Brygge Gro AS | Hospitality | 2008 |
| Akika AS | | 2018 |
| Akire Holding AS | Real estate | 2021 |
| Akker Holding AS | Financial services | 2011 |
| Akksang Ans | Arts & recreation | 2002 |
| Ako Amedyan AS | Transport & logistics | 2017 |
| Akor AS | Administrative & support | 2023 |
| Aksetøy Arkitektur AS | Professional & scientific | 2019 |
| Aksetøy AS | Professional & scientific | 2019 |
| Aksler AS | Professional & scientific | 2020 |
| Aktiv Arrangement AS | Administrative & support | 2012 |
| Aktiv Barnehjelp AS | Health & social care | 2015 |
| Aktiv Boligutleie AS | Real estate | 2023 |
| Aktiv Eiendomsmegling Trondheim AS | Real estate | 2022 |
| Aktiv Eiendomspartner AS | Real estate | 2010 |
| Aktiv Hus Design AS | Professional & scientific | 2018 |
| Aktiv Konsult AS | Arts & recreation | 2025 |
| Aktiv Servicepartner AS | Construction | 2006 |