| Snapwall AS | Professional & scientific | 2018 |
| Soelha Eiendom AS | Real estate | 2014 |
| Solbjørn Eiendom AS | Real estate | 2004 |
| Solgaard Mat AS | Wholesale & retail | 2003 |
| Solomon Auto AS | Wholesale & retail | 2016 |
| Sommerset Holding AS | | 2022 |
| Specify Events Da | Administrative & support | 2025 |
| Sped Trans AS | Transport & logistics | 2011 |
| Speki AS | | 2026 |
| Speki Holding AS | | 2026 |
| Spernes Bygg AS | Construction | 2018 |
| Spinneriveien 11 Eiendom AS | Real estate | 2021 |
| Sport & Fritid Ans | Wholesale & retail | 1996 |
| Sport Media & Invest AS | Professional & scientific | 2015 |
| Sportmann AS | Wholesale & retail | 2023 |
| Sportsmagasinet Rykkinn AS | Wholesale & retail | 2019 |
| Sr-Mesterbygg AS | Construction | 2018 |
| Stavlund Holding AS | Real estate | 2007 |
| Stenbock Holding AS | | 2024 |
| Stene Stål AS Thor Stene & Sønner | Construction | 1987 |
| Stene Stål Eiendom Halden AS | Real estate | 2002 |
| Stene Stål Eiendom Indre Østfold AS | Real estate | 2012 |
| Stene Stål Gjenvinning AS | Water & waste | 2012 |
| Stene Stål Holding AS | Real estate | 2012 |
| Stobbe Holding AS | | 2026 |
| Storespeed AS | Information & communication | 2016 |
| Stormtek AS | Professional & scientific | 2024 |
| Storveien 4 AS | Real estate | 2024 |
| Strategic Property AS | Real estate | 2013 |
| Studio Gran Interiørarkitekter AS | Professional & scientific | 2017 |
| Studio Isidor AS | Professional & scientific | 1996 |
| Studio Moyo AS | Wholesale & retail | 2026 |
| Styvehavn AS | Professional & scientific | 2016 |
| Styvehavn Holding AS | Professional & scientific | 2020 |
| Subsearemote AS | Professional & scientific | 2025 |
| Sushi & Corndog AS | Hospitality | 2025 |
| Swarovski Optik Vertriebs GmbH | Wholesale & retail | 2011 |
| Sydeng Consulting AS | Professional & scientific | 2014 |
| SØRENS1 AS | Arts & recreation | 2012 |
| T-Line Norge AS | Transport & logistics | 2015 |
| T2 Gruppen AS | Real estate | 2020 |
| Talina Produksjon AS | Arts & recreation | 2020 |
| Tamburen AS | Hospitality | 2013 |
| Tannlegene I Væktergaarden AS | Health & social care | 2007 |
| Tassen Holding AS | Real estate | 2015 |
| TBG AS | Health & social care | 1999 |
| Teglverksveien 2 AS | Real estate | 2008 |
| Teistung AS | | 2020 |
| Tekdesign AS | Professional & scientific | 2024 |
| TELI2 AS | Real estate | 2012 |
| Tempo Trading AS | Wholesale & retail | 1991 |
| Temptation Restaurant AS | Hospitality | 2025 |
| Tenax Holding AS | Financial services | 2009 |
| Terje Harsem AS | Health & social care | 2005 |
| Tg-Vedeler AS | Health & social care | 2023 |
| Tg-Vedeler Holding AS | Health & social care | 2022 |
| TGS Prediktor AS | Information & communication | 2012 |
| TH Lundblad Invest AS | Real estate | 1994 |
| Thomas Jørgensen AS | | 2024 |
| Thor Bøckmann AS | Health & social care | 2013 |
| Thor Gunnar Ryen AS | | 2020 |
| Tigris AS | Real estate | 2018 |
| Tis Invest AS | Manufacturing | 2009 |
| Titangata 11 AS | Real estate | 2021 |
| Titangata 8 AS | Manufacturing | 2007 |
| TNF Holding AS | | 2022 |
| Tofte AS | | 2018 |
| Tor Erik Lund AS | | 2020 |
| Tor O Næss Butikkinredning AS | Wholesale & retail | 1999 |
| Tor-Erik Lund Invest AS | Professional & scientific | 2004 |
| Tore Persson AS | Financial services | 2005 |
| Torp Bygg-Invest AS | Wholesale & retail | 2001 |
| Torpegata 8 a Eiendom AS | Real estate | 2012 |
| Torsnes Bygg AS | Construction | 2015 |
| Torsnes Industriservice AS | Manufacturing | 2023 |
| Torvgaten 57A AS | Real estate | 2023 |
| Total BBS AS | Professional & scientific | 2025 |
| Total Eiendomsdrift AS | Construction | 2017 |
| Total Eiendomsutvikling AS | Construction | 2013 |
| Treteknikk Eiendom Østfold AS | Real estate | 2014 |
| Treteknikk Østfold AS | Construction | 2014 |
| Trondalen Utvikling AS | Real estate | 2007 |
| Trosvik Torv 1-3 AS | Real estate | 2008 |
| Trucktech AS | Wholesale & retail | 1998 |
| Trucktech Utleie AS | Administrative & support | 2018 |
| Tse Investeringsselskap AS | Real estate | 2023 |
| TT Utvikling AS | Real estate | 2019 |
| Tyrolit AS | Wholesale & retail | 1971 |
| Tæsse Holding AS | Hospitality | 2023 |
| Ulfeng Vann Og Avløpslag SA | Water & waste | 2016 |
| Undrum Eiendom AS | Real estate | 2026 |
| Undrum Holding AS | | 2023 |
| Undrumdesign AS | Information & communication | 2021 |
| Undrumdesign AS | Information & communication | 2026 |
| Unger Fabrikker AS | Manufacturing | 1961 |
| Unni Invest Holding AS | | 2020 |
| Urskogen Holding AS | Other services | 2007 |
| Vabenken 11 & 12 AS | Real estate | 2012 |
| Vabenken 17 AS | Real estate | 2012 |
| Value Labs AS | | 2025 |