| Vikenconsult AS | Professional & scientific | 2018 |
| Viking Elektro Østfold AS | Construction | 2021 |
| Vikings AS | Information & communication | 2024 |
| Villa Øst Barnehage SA | Education | 1989 |
| Vincent Medisinske Senter AS | Health & social care | 2003 |
| Vinsalongen AS | | 2026 |
| Vinslottet AS | | 2021 |
| Vinteknikk AS | Professional & scientific | 2024 |
| Visihelp AS | Information & communication | 2022 |
| Visit Fredrikstad Og Hvaler AS | Administrative & support | 2003 |
| Visitøstfold AS | Administrative & support | 2014 |
| Vitea Tannklinikk AS | Health & social care | 2019 |
| Vitre Bygg AS | Construction | 2024 |
| Vitre Eiendom AS | Real estate | 2026 |
| Vitre Holding AS | | 2026 |
| Vix AS | Wholesale & retail | 2010 |
| Vizz AS | Professional & scientific | 2006 |
| VN Glass Montering AS | Construction | 2023 |
| Volthub AS | Wholesale & retail | 2024 |
| Vortex Surfer AS | Health & social care | 2021 |
| Vågøy Holding AS | | 2021 |
| Våstra Invest AS | Agriculture & fishing | 2018 |
| Walby Bygg & Takst AS | Professional & scientific | 2023 |
| Wallentin Invest AS | Real estate | 2013 |
| Warda Pizza Da | Hospitality | 2008 |
| Waterfront Bar Og Bistro AS | Hospitality | 2000 |
| Wave Labs AS | Information & communication | 2026 |
| Weberg Vei Og Landbrukstjenester AS | Construction | 2019 |
| Wege Holding AS | Real estate | 2005 |
| Wellness Education & Technology AS | Health & social care | 2022 |
| Westfalen AS | Professional & scientific | 2026 |
| Wex Group Invest AS | Real estate | 2020 |
| Winkler Innredninger AS | Manufacturing | 2016 |
| Winther & Abrahamsen AS | Professional & scientific | 2025 |
| Winther Hansen Holding AS | | 2022 |
| Wium Invest AS | | 2024 |
| Wolff Concept AS | Wholesale & retail | 2012 |
| Wolff Holding AS | Real estate | 2015 |
| Wolff Invest AS | | 2020 |
| X Phan Holding AS | | 2026 |
| Xenophon AS | Professional & scientific | 2012 |
| XT Fredrikstad AS | Arts & recreation | 2014 |
| Yankee AS | | 2019 |
| Yaybjorn Technology AS | Information & communication | 2026 |
| Ybb AS | Information & communication | 2026 |
| Yellow Projects AS | Financial services | 2017 |
| Yong Willgohs Holding AS | | 2024 |
| Yuuka Yuuka Sushi Fredrikstad AS | Hospitality | 2025 |
| Zakariassen Eiendom AS | Real estate | 2026 |
| Zangana Holding AS | | 2025 |
| Zemantiq Nuf | Real estate | 2009 |
| Zena AS | Information & communication | 2012 |
| Zene Holding AS | Financial services | 2015 |
| Zens Admin AS | | 2023 |
| Zero-Visjon AS | Education | 2017 |
| Zetterman Holding AS | | 2026 |
| Ziani Norge AS | Wholesale & retail | 2019 |
| ZK Elektro AS | Construction | 2019 |
| Zmedia AS | Professional & scientific | 2023 |
| Zoz Software AS | Information & communication | 2018 |
| Ztron AS | Wholesale & retail | 2020 |
| Zwara Byggtjenester AS | Construction | 2015 |
| ZZ Fredrikstad AS | Hospitality | 2024 |
| Åkb Skogstrand AS | Real estate | 2015 |
| Åsgårdbakken 3 AS | Real estate | 2024 |
| Åsle Og Jakobsen Da | Wholesale & retail | 2009 |
| Ærbe AS | Education | 2021 |
| Èli Skin AS | Wholesale & retail | 2026 |
| Øbj AS | | 2022 |
| Øby Holding AS | | 2025 |
| Øgv AS | Transport & logistics | 2020 |
| Øgv Invest AS | | 2023 |
| Øgv Transport AS | Transport & logistics | 2026 |
| Øisjøfoss Montasje AS | Construction | 2019 |
| Øivind Karlsen Holding AS | Real estate | 2007 |
| Øko Bolig AS | Real estate | 2018 |
| Øko Drift AS | Professional & scientific | 1994 |
| Øko-Data A/S | Professional & scientific | 1983 |
| Økonomi Marked AS | Professional & scientific | 2017 |
| Økonomidoktoren AS | Professional & scientific | 1993 |
| Ørmenåsen Veglag SA | Real estate | 2024 |
| Ørn Invest AS | | 2023 |
| Øst VVS AS | Construction | 2023 |
| Øst-Hus AS | Real estate | 2006 |
| Østconsult AS | Professional & scientific | 2014 |
| Østeuropeiske Delikatesser AS | Wholesale & retail | 2015 |
| Østfold Anleggsgartner AS | Administrative & support | 2019 |
| Østfold Hotelldrift AS | Hospitality | 2026 |
| Østfold Hudlegeklinikk AS | Health & social care | 2014 |
| Østfold Maler Team AS | Construction | 2022 |
| Østfold Pizza AS | Hospitality | 2010 |
| Østfold Psykologtjenester AS | Health & social care | 2012 |
| Østfold Rørleggerbedrift AS | Construction | 2025 |
| Østfold Sikkerhetsservice Alarm AS | Administrative & support | 2000 |
| Østfold Sikkerhetsservice Vakt AS | Administrative & support | 2001 |
| Østfold Solskjerming AS | Construction | 2015 |
| Østfold Trafikkdrift AS | Construction | 2023 |
| Østfoldnevrologene AS | Health & social care | 2024 |
| Østhellinga Invest AS | Construction | 2023 |
| Østhus AS | Real estate | 2012 |