| BW Gustavsen AS | | 2005 |
| By Hola AS | Arts & recreation | 2026 |
| By Noon AS | Professional & scientific | 2026 |
| Byens Fotklinikk AS | Health & social care | 2014 |
| Bygdervegen 386 AS | Real estate | 2017 |
| Bygg 1-2 Tre AS | Construction | 2020 |
| Byggallians AS | Construction | 2019 |
| Byggmester Geir Morten Olsen AS | Construction | 2006 |
| Byggmester Helle AS | Construction | 2020 |
| Byggmester Jan-Erik Zakariassen AS | Construction | 1989 |
| Byggmester Rolf Thomas Bless AS | Construction | 2003 |
| Byggmester Stian Holtbakk AS | Construction | 2013 |
| Byggmester Tor-Erik Torgersen AS | Construction | 2024 |
| Byggmester Zakariassen AS | Construction | 2026 |
| Byggmontasje Og Punktfundament Ans | Construction | 2010 |
| Byggplast Båtutstyr AS | Wholesale & retail | 1992 |
| Bylegen Legesenter Da | Health & social care | 2013 |
| Bylegen Risnes AS | Health & social care | 2017 |
| Byro AS | Professional & scientific | 2021 |
| Byro Web Studio AS | Professional & scientific | 2019 |
| Byrå Bacchus Ans | Professional & scientific | 1991 |
| Brødr. Lindberg A/S | Manufacturing | 1988 |
| Båt Og Håndtverk AS | Manufacturing | 2015 |
| Båtlageret AS | Real estate | 2004 |
| Båtpartner Fredrikstad AS | Manufacturing | 2020 |
| Bøx AS | Information & communication | 2024 |
| C H Evensen Industriovner AS | Manufacturing | 2010 |
| C-Holding- AS | Financial services | 2018 |
| C6 Holding AS | | 2024 |
| C7 Eiendom AS | Real estate | 2014 |
| Cabelo Dame & Herrefrisør AS | Other services | 2016 |
| Cabelo Hair AS | Other services | 2021 |
| Cadur Consult AS | Real estate | 1988 |
| Cagell AS | Arts & recreation | 2022 |
| Caks Holding AS | Real estate | 2019 |
| Calac Invest AS | Wholesale & retail | 2024 |
| Calendula Forlag AS | Information & communication | 2026 |
| Calendula Holding AS | | 2026 |
| Calendula Stories AS | Arts & recreation | 2026 |
| Callus Eiendom AS | Real estate | 2006 |
| Campino Fredrikstad AS | Hospitality | 2018 |
| Card 2 AS | Real estate | 2019 |
| Carxtra AS | Wholesale & retail | 2023 |
| Casa AS | Real estate | 1995 |
| Ce-Ci AS | Wholesale & retail | 1986 |
| Center Billakkering AS | Other services | 2024 |
| Centpro AS | Information & communication | 2015 |
| Centrum Face & Body Clinique AS | Other services | 2002 |
| Centrum Fysioterapi AS | Health & social care | 2010 |
| Centrum Helse AS | Health & social care | 2016 |
| Centrum Invest AS | Financial services | 1992 |
| Chang Cheng AS | Hospitality | 1991 |
| Chang Cheng Restaurant AS | Hospitality | 2022 |
| Chans Ans | Real estate | 1998 |
| Chicago Barbershop AS | Other services | 2024 |
| Chiyo Agency AS | Professional & scientific | 2025 |
| Cho AS | Construction | 2019 |
| Choco Loco AS | Hospitality | 2023 |
| CHR. Solgaard & Co AS | Real estate | 2021 |
| Christianslund Allè 2 AS | Real estate | 2011 |
| Christianslund Blomster AS | Wholesale & retail | 2024 |
| Christianslund Frisør AS | Other services | 2017 |
| Christianslund Legekontor Da | Health & social care | 2011 |
| Christine JS Holding AS | Real estate | 2012 |
| Cicignon Eiendom AS | Real estate | 2018 |
| Citadel Invest AS | Real estate | 2007 |
| City Burger Fredrikstad AS | Hospitality | 2025 |
| City Hotel Fredrikstad AS | Hospitality | 2006 |
| City Scene Produksjoner AS | Arts & recreation | 2019 |
| Cityplan AS | Real estate | 2008 |
| Claudio AS | Information & communication | 2025 |
| CM Auto AS | Wholesale & retail | 2019 |
| Cmo Consult AS | Professional & scientific | 2018 |
| Cmo Contractor AS | Construction | 2020 |
| Cmo Engineering AS | Construction | 2019 |
| Cmo Invest AS | Professional & scientific | 2021 |
| Cmo Stålbygg Øst AS | Construction | 2022 |
| Cncgarasjen AS | Professional & scientific | 2018 |
| Coach Schulstad AS | Education | 2025 |
| Cocos Design AS | Wholesale & retail | 2023 |
| Colmenar AS | Professional & scientific | 2021 |
| Colour Me Beautiful Norge AS | Other services | 2026 |
| Compact Door Scandinavia AS | Manufacturing | 2002 |
| Competencia AS | Real estate | 2015 |
| Comsafe AS | Construction | 2012 |
| Connexa AS | Professional & scientific | 2026 |
| Consultiva AS | Professional & scientific | 2021 |
| Consultx AS | Professional & scientific | 2014 |
| Coolways Norge AS | Manufacturing | 2019 |
| Corneli AS | Professional & scientific | 2007 |
| Cornelius Capital AS | Information & communication | 2024 |
| Coruscant Investment Group AS | Information & communication | 2006 |
| Cosmetic Art AS | Other services | 2023 |
| Cotec AS | | 1986 |
| Covest Holding AS | Real estate | 2023 |
| Coyote Piercing & Ink Da | Other services | 2009 |
| Creation & Design AS | | 1987 |
| Creative Media Group AS | Administrative & support | 2024 |
| Critic Holding AS | Real estate | 2022 |
| Critic Invest AS | Real estate | 2022 |