| 1045 Invest AS | | 2024 |
| 1910-BYGGET AS | Real estate | 2021 |
| 29 Invest AS | Financial services | 2014 |
| 33 Street Food AS | Hospitality | 2025 |
| 3TECH AS | Professional & scientific | 2021 |
| 64 Garasje AS | Real estate | 2024 |
| 64 Næring AS | Real estate | 2024 |
| A Bygg & Bad AS | Construction | 2018 |
| A-B Legetjenester AS | Health & social care | 2026 |
| A.C Bygg AS | Construction | 2023 |
| A.C Eiendom AS | Construction | 2019 |
| A.C Holding AS | Construction | 2023 |
| A.H. Holding AS | Financial services | 2016 |
| A.H.G Holding AS | | 2023 |
| Aaxo AS | | 2026 |
| Abc Bilutleie AS | Administrative & support | 2020 |
| Abrakadabra Communication AS | Professional & scientific | 1996 |
| Absolutt Økonomi AS | Professional & scientific | 2010 |
| Accounting and Consulting AS | Professional & scientific | 2019 |
| Actors AS | Information & communication | 2018 |
| Adiante AS | Real estate | 2001 |
| Advokat Gaute Nilsen AS | Professional & scientific | 2018 |
| Advokat Imna Harald Otterstad AS | Professional & scientific | 1998 |
| Advokatfirmaet Bjørge - Skaaraas & Co AS | Professional & scientific | 2002 |
| Advokatfirmaet Grindstad & Co AS | Professional & scientific | 2024 |
| Advokatfirmaet Ytterbøl & Co AS | Professional & scientific | 1996 |
| Advokathuset Sarpsborg Da | Professional & scientific | 2004 |
| Adware Da | Information & communication | 1999 |
| Afry Consult AS | Professional & scientific | 1983 |
| Age With Grace AS | Wholesale & retail | 2022 |
| Agnalt Holding AS | | 2021 |
| Agne Strøm AS | Real estate | 2021 |
| Agrideler AS | Wholesale & retail | 2024 |
| Ahik Eiendom AS | Wholesale & retail | 2018 |
| Aion Ventures AS | | 2025 |
| Ajour Audit AS | Professional & scientific | 2020 |
| Akj Eiendom AS | Real estate | 1975 |
| Akselsen Ans | Transport & logistics | 1999 |
| Aktiv Sarpsborg AS | Real estate | 2024 |
| Aktix AS | Wholesale & retail | 2018 |
| Albert Moeskaus Vei 27 AS | Real estate | 1994 |
| Albert Moeskaus Vei AS | Real estate | 2018 |
| Alf Bjørnstad AS | Real estate | 1981 |
| Alf Graarud Utleie AS | Real estate | 2023 |
| Alfa Omega Regnskapsbyrå AS | Professional & scientific | 2005 |
| Alfa Omsorgtjenester AS | Health & social care | 2018 |
| Alfakrøll Frisør AS | Other services | 2021 |
| Alipaga Med AS | Health & social care | 2025 |
| All-Regnskapservice AS | Professional & scientific | 2003 |
| All-Transport AS | Transport & logistics | 1989 |
| Alma Helse AS | Health & social care | 2024 |
| Alshorfei Viken Byggservice AS | Construction | 2023 |
| Alt Av Spill AS | Wholesale & retail | 2025 |
| Alvim Barnehage AS | Education | 2013 |
| Alvim Energistasjon AS | Wholesale & retail | 2025 |
| AM-1 Holding AS | | 2017 |
| Am-Bygg AS | Construction | 2022 |
| Amt Holding AS | Professional & scientific | 2022 |
| Andreas Borge AS | Real estate | 2016 |
| Andreas Onsum AS | Real estate | 1999 |
| Andreas Thorsrud AS | Information & communication | 2013 |
| Anmada AS | Real estate | 2024 |
| Apex Engineering AS | Professional & scientific | 2023 |
| Arcaio AS | Construction | 2025 |
| Arctic Appetites AS | Wholesale & retail | 2024 |
| Arenas AS | Administrative & support | 2020 |
| Arild Mathisen AS | Professional & scientific | 1999 |
| Arkitektkontoret Konrad Halvorsen AS | Professional & scientific | 1998 |
| Arnebråtveien Barnehage AS | Education | 2004 |
| Aron Import AS | Wholesale & retail | 2015 |
| Arora AS | Wholesale & retail | 2009 |
| Art Sushi Sarpsborg AS | Hospitality | 2024 |
| Arve Tvete & Co AS | Wholesale & retail | 1977 |
| AS Boligselskapet Kirkegaten 14 | Households | 1956 |
| AS Boligselskapet Ulfhildsgt 6 | Households | 1955 |
| AS Husfliden Sarpsborg | Wholesale & retail | 1999 |
| AS Norbo Import Agentur | Real estate | 1985 |
| AS Tress | Real estate | 1961 |
| Ashti Skincare AS | Other services | 2016 |
| Ask Eiendomsmegling Sarpsborg AS | Real estate | 2021 |
| Askeladden Barnehage Borg Albert Moeskausvei AS | Education | 2005 |
| Askeladden Barnehage Borg ST. Nikolasgate AS | Education | 2023 |
| Askeladden Barnehage Borg Turnusbarnehage Færdersgt AS | Education | 2023 |
| Atlas Transport AS | Transport & logistics | 2023 |
| Atraps AS | | 2024 |
| Atri Byggprosjektering AS | Professional & scientific | 1990 |
| Autoin Bilskade Sarpsborg AS | Other services | 2016 |
| Axel Holding AS | Wholesale & retail | 2018 |
| Axerde AS | Real estate | 2023 |
| B F Lande AS | Wholesale & retail | 2019 |
| B&L Kuldeservice AS | Construction | 2026 |
| Baba Baby AS | Wholesale & retail | 2021 |
| Babylon Pizza Da | Hospitality | 2015 |
| Bac Holding AS | Information & communication | 2017 |
| Bakkeli Eiendom AS | Real estate | 2025 |
| Bakkeli Invest AS | Real estate | 2016 |
| Bala Bygg Og Rehabilitering AS | Construction | 2016 |
| Banda Borg AS | Wholesale & retail | 2022 |
| Banh Mi Baguette AS | Hospitality | 2025 |
| Bankbrygga Handelseiendom AS | Real estate | 2009 |