| 10 X Holding AS | Wholesale & retail | 2013 |
| 2 Clap Studio Da | Information & communication | 2013 |
| 35MPA AS | | 2019 |
| 365 Economy AS | Professional & scientific | 2009 |
| A Bee AS | Administrative & support | 2023 |
| A&H Eiendomsutvikling AS | Real estate | 2011 |
| Aamo AS | Wholesale & retail | 2026 |
| AB Turlid AS | Health & social care | 2026 |
| Aba Viking Cargo AS | Transport & logistics | 2024 |
| Abs Consulting AS | Professional & scientific | 2005 |
| Ac Bedriftsrådgivning Da | Professional & scientific | 2005 |
| Adv Capital AS | Professional & scientific | 2016 |
| Adviseit Nuf | Professional & scientific | 2006 |
| Advokat Lars Haugen AS | Professional & scientific | 2010 |
| Advokatfirma Olafsen AS | Professional & scientific | 2007 |
| AI Business Lab AS | Information & communication | 1998 |
| Aia Investments AS | | 2025 |
| Airfix Nordic Invest | Real estate | 2016 |
| Airfix Nordic Nuf | Manufacturing | 2016 |
| Akademiet Ungdomsskole Lier AS | Education | 2018 |
| Aksjeselskapet Centraltrykkeriet Invest | Professional & scientific | 1906 |
| Aktiv Dokumentbehandling AS | Information & communication | 2017 |
| Alba Company AS | Wholesale & retail | 2020 |
| Aleron Invest AS | | 2020 |
| Alfa Omega AS | Construction | 2023 |
| Alfa Omega Entreprenør AS | Construction | 2018 |
| Alkriva AS | Administrative & support | 2004 |
| Alkriva Holding AS | Wholesale & retail | 2022 |
| Almankaas Takst AS | Professional & scientific | 2011 |
| Alpegull AS | Administrative & support | 2023 |
| Altana AS | Wholesale & retail | 2006 |
| Altx AS | Professional & scientific | 2023 |
| Ama Partner AS | Construction | 2022 |
| An Hansen Holding AS | | 2026 |
| Anita Gjelsten Holding AS | Other services | 2019 |
| Annet Format AS | Professional & scientific | 1990 |
| Ans Frantz Hegg Gartneri | Real estate | 1989 |
| Apotekgården Lier AS | Real estate | 2016 |
| Arctic Valves AS | Manufacturing | 2014 |
| Arcus Vita Nøkkelhåndtering AS | Wholesale & retail | 2021 |
| Are Aamodt Invest AS | Financial services | 2005 |
| Arentz Invest AS | | 2013 |
| Ariels Klinikk AS | Health & social care | 2026 |
| Arka Bygg AS | Construction | 2005 |
| Armé Eiendom AS | Real estate | 2018 |
| Arn Solutions AS | Wholesale & retail | 2025 |
| Aruba Eiendom AS | Real estate | 1981 |
| AS Ramses | Wholesale & retail | 1988 |
| Asakskogen Birøkt AS | Agriculture & fishing | 2017 |
| Ask Vingård AS | Agriculture & fishing | 2025 |
| Asker Bilservice AS | Other services | 2002 |
| Assemblin Ventilasjon AS | Construction | 1992 |
| Assistent Partner AS | Construction | 1996 |
| Atrack Entreprenør AS | Construction | 2001 |
| Aucu Exploration AS | Mining & quarrying | 2013 |
| Aw Invest AS | Financial services | 2005 |
| Bakerikvartalet I AS | Real estate | 1993 |
| Bakk-Kristiansen Holding AS | | 2026 |
| Bakkeli Barnehage SA | Education | 2005 |
| Balder Software AS | Information & communication | 2026 |
| Bang Pederssen Transport Da | Transport & logistics | 2005 |
| Bankbygget Lier AS | Real estate | 2006 |
| Baru Eiendom AS | Real estate | 2013 |
| Bela Regnskap AS | Professional & scientific | 2016 |
| Bella Misura AS | Professional & scientific | 2024 |
| Belvedere Holding AS | Financial services | 2012 |
| Berand Invest AS | Financial services | 2005 |
| Bergmann & Holm Ans | Wholesale & retail | 1996 |
| Bertel O. Steen Drammen AS | Other services | 1988 |
| Berthinussen Eiendom AS | Real estate | 2009 |
| Bese Auto AS | Wholesale & retail | 2011 |
| Bhandari Bygg Og Utvikling AS | Real estate | 2016 |
| Bil-Demontørenes Dataring SA | Information & communication | 1997 |
| Bisken Barnehage AS | Other services | 2020 |
| Bjerkaas AS | Education | 2019 |
| Bjertnesmoen AS | | 2024 |
| BJH Consulting AS | Professional & scientific | 2023 |
| Bjørland Mørk Holding AS | | 2018 |
| Blankbil AS | Wholesale & retail | 2001 |
| Bli Brun Solstudio AS | Other services | 2013 |
| Boletus AS | Real estate | 2000 |
| Boliggiganten 14 AS | Real estate | 2015 |
| Boliggiganten 18 AS | Real estate | 2015 |
| Boliggiganten 20 AS | Real estate | 2015 |
| Boliggiganten AS | Real estate | 2017 |
| Boligutleie Lier AS | Real estate | 2012 |
| Bomasa Holding AS | Real estate | 1998 |
| Bomath Holding AS | | 2015 |
| Borgar Steinsets Vei 10 Og 14 AS | Real estate | 2018 |
| BPG AS | Construction | 2012 |
| Brillianne AS | Professional & scientific | 2020 |
| Briskeby Videregående Skole AS | Education | 2004 |
| Brkt AS | Administrative & support | 2022 |
| Broder Holding AS | | 2019 |
| Brodyret AS | Real estate | 2012 |
| Brolabs AS | Wholesale & retail | 2025 |
| Bromodi AS | Real estate | 2026 |
| Broom AS | Arts & recreation | 2005 |
| Brus Invest AS | | 2022 |
| Bruveien Utvikling AS | Real estate | 2019 |