| Eker Group AS | Professional & scientific | 1996 |
| Eker Performance AS | Wholesale & retail | 2004 |
| Eker Solutions AS | Wholesale & retail | 2024 |
| Eker Technologies AS | Professional & scientific | 2024 |
| Elektrofon AS | Professional & scientific | 2019 |
| Elektroinstallatør Kjærsund AS | Construction | 2014 |
| Ellevseth AS | Construction | 2018 |
| Emec Invest AS | | 2021 |
| Emil Mørchsvei 25 AS | Real estate | 2019 |
| Emm K. AS | Wholesale & retail | 2021 |
| Emmaboda Glas AB | Manufacturing | 2001 |
| Emmily AS | Real estate | 2006 |
| Emv 30 AS | Real estate | 2022 |
| Energea AS | Professional & scientific | 2013 |
| Energifabriken Norge AS | Wholesale & retail | 2015 |
| Energifysikk AS | Professional & scientific | 2026 |
| Energy Holding AS | Administrative & support | 2020 |
| Epiguard AS | Professional & scientific | 2015 |
| Eplehagen Eiendomsutvikling AS | Real estate | 2011 |
| Eqgrid AS | Information & communication | 2025 |
| Erik Haraldsen Maskinservice AS | Manufacturing | 2012 |
| Erik Ødegård AS | | 2020 |
| Esbo AS | Real estate | 2004 |
| Espen Kjellås Data AS | Information & communication | 1998 |
| Espen Ødegård AS | | 2023 |
| Estar AS | Real estate | 2006 |
| Estar Næring AS | Real estate | 1985 |
| Etek Energi AS | Real estate | 2015 |
| Eva Hystad Holding AS | | 2019 |
| Eventyrlåven AS | | 2008 |
| Everest AS | | 2023 |
| Falck Dykkertjeneste AS | Construction | 2023 |
| Familiespor AS | Education | 2026 |
| Family Trening Fredrikstad Øst AS | Arts & recreation | 2022 |
| Fargefabrikken AS | Arts & recreation | 2013 |
| Feiergaarden Eiendom AS | Real estate | 2012 |
| Festningsbyen AS | Arts & recreation | 2012 |
| FG Eiendom AS | Real estate | 1988 |
| Fhird AS | Information & communication | 2009 |
| Fixr Da | Wholesale & retail | 2009 |
| Fjeld Bilverksted AS | Other services | 2017 |
| Fjellet Eiendom AS | Real estate | 2004 |
| Flexi Invest Da | Real estate | 2007 |
| FLT Eiendom AS | Real estate | 2021 |
| FLT Invest AS | Transport & logistics | 2022 |
| Fly Without Wings AS | Professional & scientific | 2025 |
| Fly Without Wings Holding AS | Professional & scientific | 2025 |
| Flyt VVS AS | Construction | 2021 |
| Fmcc Drift Og Utleie AS | Administrative & support | 1998 |
| FMP Prosjekt AS | Wholesale & retail | 2018 |
| Fo-Kus AS | Professional & scientific | 2019 |
| Fokus Direkte AS | Information & communication | 2004 |
| Foyn Pharma Consulting AS | Professional & scientific | 2026 |
| Fra Øverste Hylle Filmdistribusjon AS | Information & communication | 2021 |
| Framo Holding AS | Manufacturing | 2014 |
| Fredrik Haven Invest AS | Professional & scientific | 2016 |
| Fredrikstad Cargo Terminal AS | Transport & logistics | 2025 |
| Fredrikstad Elektro AS | Construction | 2023 |
| Fredrikstad Fjernvarme AS | Energy | 2000 |
| Fredrikstad Innovasjonspark AS | Real estate | 2009 |
| Fredrikstad Langtransport AS | Transport & logistics | 1996 |
| Fredrikstad Mikrobryggeri AS | Manufacturing | 2013 |
| Fredrikstad Naprapat- Og Hudpleieklinikk AS | Health & social care | 2010 |
| Fredrikstad Rør AS | Construction | 2019 |
| Fredrikstad Spillerinvest AS | Administrative & support | 2005 |
| Fredrikstad Storbilvask AS | Other services | 2020 |
| Fredrikstad Transportforum AS | Transport & logistics | 1989 |
| Fredrikstad Vann Og Varme AS | Construction | 2020 |
| Fremek AS | Manufacturing | 2017 |
| Frewifo Invest AS | Construction | 2023 |
| Frip Holding AS | Real estate | 2021 |
| Fro Eiendom AS | Real estate | 2024 |
| Frontkom AS | Professional & scientific | 2018 |
| Frontkom Experience AS | Information & communication | 2022 |
| Frontkom Group AS | Professional & scientific | 2022 |
| Frontkom Invest AS | | 2022 |
| Frostline AS | Transport & logistics | 2025 |
| Frydenlunds AS | Arts & recreation | 2025 |
| Frydia AS | Real estate | 2025 |
| Frydia Gaarden AS | Real estate | 2025 |
| Frydia Total AS | Real estate | 2026 |
| Fuglehundakademiet AS | | 2026 |
| Færingen Invest AS | Professional & scientific | 2005 |
| G E Holding AS | Construction | 1999 |
| Gaards-Service AS | Administrative & support | 1998 |
| Gaia Textiles AS | Wholesale & retail | 2016 |
| Galleri Gunne AS | Manufacturing | 2012 |
| Galleriet Vinbar AS | Hospitality | 2020 |
| Gamle Fredrikstad Bigård AS | Agriculture & fishing | 2023 |
| Gamle Kongevei 21 AS | Real estate | 2017 |
| Gamlebyen Arkitekter AS | Professional & scientific | 2021 |
| Gamlebyen Byinvest AS | Real estate | 2022 |
| Gamlebyen Elektriske AS | Construction | 2014 |
| Gamlebyen Festivaldrift AS | Arts & recreation | 2012 |
| Gamlebyen Hotell Fredrikstad AS | Hospitality | 2015 |
| Gamlebyen Kultur AS | Arts & recreation | 2019 |
| Gamlebyen Modelljernbanesenter AS | Arts & recreation | 2013 |
| Garderobe-Mannen AS | Wholesale & retail | 2022 |
| Garp Invest AS | Professional & scientific | 2020 |
| Gaupefaret AS | Real estate | 2017 |