| Tuneveien 89 AS | Real estate | 2000 |
| Tvete-Berger AS | Construction | 2021 |
| Twenty Seven Holding AS | | 2023 |
| Thoens Agenturer AS | Wholesale & retail | 1984 |
| Tømrer Kristiansen AS | Construction | 2019 |
| Tømrer Og Snekkerservice AS | Construction | 2023 |
| Tørkopp Fus Barnehage AS | Education | 2018 |
| Ulvøysund Hytteutleie AS | Hospitality | 2023 |
| Una AS | Administrative & support | 1998 |
| Urban Food AS | Hospitality | 2016 |
| Ut I Det Fri AS | Education | 2021 |
| Valen Consult AS | Professional & scientific | 2019 |
| Valhalla Vest AS | Real estate | 1987 |
| Valhalla Vest Bolig AS | Real estate | 2025 |
| Valler GEN2 AS | Real estate | 2020 |
| Value Fredrikstad AS | Professional & scientific | 2018 |
| Varig Rådgivning AS | Professional & scientific | 2024 |
| Vaskeri Konsult AS | Professional & scientific | 2022 |
| Vassbygda Maskin AS | Construction | 2021 |
| VB Media AS | Information & communication | 2012 |
| VD Design AS | Professional & scientific | 2020 |
| Vegard Johansen AS | Construction | 2005 |
| Veksthuset AS | Professional & scientific | 2020 |
| Veldig Sulten AS | Hospitality | 2013 |
| Vesterelva Legesenter AS | Health & social care | 2021 |
| Veterinær Wennersberg AS | Professional & scientific | 2012 |
| Viken Bolig Og Eiendomsutvikling AS | Real estate | 2021 |
| Viken Marinesenter AS | Wholesale & retail | 2020 |
| Vin & Matglede AS | Administrative & support | 2015 |
| Viridi Futurum AS | | 2007 |
| VIRVEL1 AS | Arts & recreation | 2016 |
| Vraktangen Fyr SA | Arts & recreation | 2024 |
| Værste AS | Real estate | 2006 |
| Værste Forvaltning AS | Real estate | 2010 |
| Værste Prosjekt AS | Real estate | 2013 |
| Værste Utvikling AS | Real estate | 2013 |
| Værstetorvet 2 AS | Real estate | 2022 |
| Wallin Invest AS | Professional & scientific | 2024 |
| Wang Fredrikstad AS | Education | 2005 |
| Waveform 5 AS | Professional & scientific | 2024 |
| Wennersberg Eiendom AS | Real estate | 2024 |
| Wic Holding AS | Professional & scientific | 2020 |
| Wican Holding AS | Real estate | 2004 |
| Wican IT AS | Information & communication | 2003 |
| Wican Marked AS | Information & communication | 2003 |
| Wican Regnskap AS | Professional & scientific | 2004 |
| Wican Regnskap Service AS | Professional & scientific | 2015 |
| Wik & Walsøe AS | Professional & scientific | 2014 |
| Wik & Walsøe Handel AS | Wholesale & retail | 2015 |
| Willys Pizza AS | Hospitality | 2024 |
| Winbladh Asfalt & Maskin AS | Construction | 2023 |
| Winbladh Holding AS | Construction | 2018 |
| Windowmaster Bsi AS | Information & communication | 1997 |
| Wisur Holding AS | | 2014 |
| Wiwa Holding AS | Professional & scientific | 2014 |
| X&Y Consulting AS | Professional & scientific | 2024 |
| Xtremedsign AS | Professional & scientific | 2016 |
| Yearbay Invest AS | Financial services | 2020 |
| Yggdrasil Data Plattform AS | Information & communication | 2018 |
| Zell Invest AS | | 2015 |
| Ål Holding AS | Financial services | 2010 |
| Åsgård Utvikling AS | Professional & scientific | 2019 |
| Åsgårdhagen AS | Real estate | 2016 |
| Ørmen Bygg & Anlegg AS | Real estate | 2025 |
| Ørmen Holding AS | | 2026 |
| Øst-Revisjon AS | Professional & scientific | 2018 |
| Østfold Brønnspyling AS | Administrative & support | 2025 |
| Østfold Teater AS | Arts & recreation | 2019 |