| Spider Boat AS | Manufacturing | 2019 |
| Spireriet AS | Wholesale & retail | 2026 |
| Steinriket Norge AS | Manufacturing | 1989 |
| Stimar AS | Real estate | 2015 |
| Strandberg Stein AS | Manufacturing | 1991 |
| Strandberg Utemiljø AS | Manufacturing | 2021 |
| Strandvik Invest AS | Manufacturing | 2005 |
| Stål- Og Landbruksbygg AS | Construction | 2006 |
| Søndre Kjerringvik Veilag SA | Real estate | 2020 |
| Tannlege Charlotte Johansen AS | Health & social care | 2024 |
| Teien Bygg Og Anlegg AS | Professional & scientific | 2019 |
| Teien Holding AS | Real estate | 2020 |
| The Smart Company AS | Information & communication | 2015 |
| Thoma Holding AS | Financial services | 2005 |
| Tisthammer Holding AS | | 2025 |
| Tjølling Bil & Båt AS | Other services | 2005 |
| Tjølling Fysio & Manuellterapi AS | Health & social care | 2022 |
| Tjølling Jordvanning SA | Agriculture & fishing | 1973 |
| Tjølling Legekontor Ans | Health & social care | 2018 |
| Tjølling Mek. Verksted AS | Manufacturing | 2019 |
| Tjølling Regnskap SA | Professional & scientific | 1954 |
| Tjølling Vaktmestertjenester AS | Administrative & support | 2022 |
| Tjøllingveien 608 AS | Real estate | 2019 |
| Tojelu AS | Information & communication | 2026 |
| Tollerudelva AS | Hospitality | 2000 |
| Torp Investment AS | | 2023 |
| Torvik Jensen AS | Real estate | 2005 |
| Tot Invest AS | Financial services | 2005 |
| Total-Økonomi AS | Professional & scientific | 2008 |
| Traditions Gourmet Pepper Jellies AS | Hospitality | 2024 |
| Trine Og Heges Salong AS | Other services | 1999 |
| Tse Invest AS | Professional & scientific | 2005 |
| Tveter Invest AS | Real estate | 2004 |
| Tømrer Finn Erik Håkestad AS | Construction | 2021 |
| Ula Camping AS | Hospitality | 2016 |
| Ulabrand Holding AS | | 2025 |
| Ulsvaag AS | Agriculture & fishing | 2022 |
| Verdifaktor AS | Education | 2014 |
| Vestfold Eiendomservice AS | Administrative & support | 2025 |
| Vestfold Pizza AS | Hospitality | 2023 |
| Vetalis AS | Professional & scientific | 2025 |
| Vic Drift AS | Administrative & support | 2025 |
| Viken Consulting AS | Real estate | 1996 |
| Vikerøya Invest AS | | 2025 |
| Vittersø Maskin AS | Construction | 2019 |
| Weber Fysioterapi AS | Health & social care | 2013 |
| Wendel Holding AS | | 2019 |
| Wensilk Da | Wholesale & retail | 2007 |
| Werner Johansen AS | Construction | 2026 |
| Woodbury AS | Professional & scientific | 2024 |
| XXL Event AS | Administrative & support | 2001 |
| Yngve Lystad Invest AS | Real estate | 2008 |
| Østby Holding AS | | 2007 |
| Østby Økonomiservice AS | Information & communication | 1994 |