| Skanlat AS | Construction | 2025 |
| SKG Modulhus AS | Real estate | 2025 |
| SKG Transport AS | Transport & logistics | 2024 |
| Skibstad Holding AS | | 2024 |
| Skipstad Camping AS | Hospitality | 2013 |
| Skipstad HMS AS | Health & social care | 2011 |
| Skjelsbo Fellesbrygge SA | Real estate | 1972 |
| Skjelsbo Holding AS | | 2023 |
| Skjelsbo Invest AS | Real estate | 2001 |
| Skjelsbutoppen AS | Real estate | 2019 |
| Skjærhalden Marina AS | Wholesale & retail | 2011 |
| Skjærhalden Marina Trade AS | Wholesale & retail | 2026 |
| Skogdrone Da | Professional & scientific | 2019 |
| Slefs Holding AS | Financial services | 2016 |
| Smartlab Norway AS | Professional & scientific | 2015 |
| Softworks AS | Information & communication | 2001 |
| Spjæringen AS | Agriculture & fishing | 2007 |
| Spjæringen Holding AS | Agriculture & fishing | 2007 |
| Spjæringen II AS | Agriculture & fishing | 2007 |
| Stokken Båt & Motor AS | Wholesale & retail | 1997 |
| Stokken Båt Invest AS | Wholesale & retail | 2022 |
| Stokken Båt Og Motor Marina AS | Wholesale & retail | 2026 |
| Strandbakken/Rød Søndre Va SA | Water & waste | 2022 |
| Strandbakken/Rød Søndre Va Utbygging SA | Construction | 2022 |
| Structuras AS | | 2024 |
| Strøknesfjella Holding AS | | 2025 |
| Svein Erik Fjellgaard AS | Transport & logistics | 2020 |
| Svingen Håndverk AS | Construction | 2024 |
| Søberg Fiske Og Gårdsservice Da | Agriculture & fishing | 2025 |
| T.Andersen Holdning AS | Real estate | 2022 |
| Tape Consulting AS | Professional & scientific | 2000 |
| The Ocean Counsel AS | Professional & scientific | 2026 |
| Thelle Teknologi AS | Wholesale & retail | 2016 |
| Tilvalg AS | Professional & scientific | 2019 |
| TKF Holding AS | Wholesale & retail | 2008 |
| Toplogic AS | Professional & scientific | 2013 |
| Total Management AS | Professional & scientific | 1991 |
| Transport Og Båtservice AS | Transport & logistics | 2020 |
| Tredalen Speidersenter AS | Hospitality | 2025 |
| Triangel Data Da | Professional & scientific | 1993 |
| Tømrer Bøe-Pedersen AS | Construction | 2018 |
| UNIT654 AS | Real estate | 2013 |
| United Holdings AS | Professional & scientific | 2012 |
| Utgaardskilens Indkjøpslag SA | Wholesale & retail | 1932 |
| Vann- Og Avløpslaget Gravningen SA | Water & waste | 2007 |
| Veruco Eiendom AS | Real estate | 2002 |
| Vesterøy Bygg AS | Wholesale & retail | 1986 |
| Via Ovidia AS | Wholesale & retail | 2018 |
| Vigs Linefisk AS | Agriculture & fishing | 2014 |
| Vikerhavna Marina Og Slipp AS | Arts & recreation | 2003 |
| Villsauen Ans | Agriculture & fishing | 2007 |
| Vista Borealis AS | Information & communication | 1994 |
| Waste Management AS | Professional & scientific | 2005 |
| WHS Holding AS | | 2025 |
| Wittus Holding Invest AS | | 2002 |
| Worknlife AS | Professional & scientific | 2017 |
| Yezz AS | Wholesale & retail | 2016 |
| Åsebu Skolebakken Vann Og Avløp SA | Water & waste | 2010 |
| Østad-Storengkilen Va Drift SA | Water & waste | 2018 |
| Østad-Storengkilen Va Utbygging SA | Water & waste | 2018 |
| Østfold Byggtapetsering AS | Construction | 1998 |
| Østlandske Kuldeservice AS | Construction | 2001 |
| Øykroa Hvaler AS | Hospitality | 2012 |