| Felice AS | | 2021 |
| Fern Eiendom AS | Real estate | 2013 |
| Fersk Og Frys AS | Wholesale & retail | 2026 |
| Festningsavenyen 115 AS | Real estate | 2012 |
| Finansbyrået AS | Professional & scientific | 2015 |
| Finanshuset AS | Real estate | 2002 |
| Finckelsen & Hilmarsen Revisjon AS | Professional & scientific | 2020 |
| Fiol Demeter AS | | 2023 |
| Fireco AS | Professional & scientific | 1991 |
| Firma Larsen AS | Information & communication | 2016 |
| Firmus Group AS | Real estate | 2006 |
| Firmus Hospitality AS | Professional & scientific | 2022 |
| Firmus Properties AS | Real estate | 2008 |
| Firmus Real Estate AS | Real estate | 2010 |
| First Edition Kapital AS | Wholesale & retail | 2025 |
| Fiskemesteren Da | Wholesale & retail | 2001 |
| Fjeldberg Bruk Eiendom AS | Real estate | 2024 |
| Fjeldberg Marina AS | Arts & recreation | 1999 |
| Fjord Management Consulting AS | Professional & scientific | 2022 |
| FK Eiendom Datter AS | Real estate | 2018 |
| Flikk Flakk Trening Og Kompetanse- Senter AS | Arts & recreation | 2006 |
| Floa Eiendom AS | Real estate | 2018 |
| Flodin Data Systemer AS | Information & communication | 2016 |
| Flodin Eiendom AS | Real estate | 2012 |
| Flodin Holding AS | | 2014 |
| Flora Restaurant AS | Hospitality | 2014 |
| Flowit AS | Professional & scientific | 2012 |
| Flowplanet AS | Professional & scientific | 2014 |
| Flowtek AS | Manufacturing | 2025 |
| Fluffy Days AS | Other services | 2024 |
| Flyt Design & Kommunikasjon AS | Information & communication | 2022 |
| Flyt Event AS | Arts & recreation | 2019 |
| Flyt Forlag AS | Information & communication | 2013 |
| Fmrs Invest AS | | 2025 |
| Focus Pharma AS | Wholesale & retail | 2002 |
| Foliering & Dekor AS | Manufacturing | 2023 |
| Follo Alarm AS | Construction | 1997 |
| Follow No Crowd Holding AS | | 2024 |
| Food Holding AS | | 2024 |
| Foodart AS | Hospitality | 2010 |
| Foodcourt Da | Arts & recreation | 2004 |
| Forbrukerteam Da | Administrative & support | 2004 |
| Formoe AS | Professional & scientific | 2021 |
| Fors.Da | Wholesale & retail | 2003 |
| Forsberg Eiendom AS | Real estate | 2021 |
| Forsberg Invest AS | Professional & scientific | 2013 |
| Fortil AS | Information & communication | 2016 |
| Forvaltning AS | Real estate | 2005 |
| Foss & Co Østfold AS - Eiendomsmegling | Real estate | 1996 |
| Fossum & Ingerø AS | Wholesale & retail | 2003 |
| Fossum Eiendom AS | Wholesale & retail | 1914 |
| Fossum Jernvare AS | Wholesale & retail | 2017 |
| Fossum Workwear AS | Wholesale & retail | 2022 |
| Fotograf Østnes AS | Manufacturing | 1990 |
| Fougner Auto AS | Wholesale & retail | 2025 |
| FQ Enterprises AS | Information & communication | 2020 |
| Framover Eiendom AS | Real estate | 2020 |
| Frausini Invest AS | Real estate | 2019 |
| Frebo AS | Real estate | 2004 |
| Freca AS | Financial services | 2016 |
| Fredal AS | | 2011 |
| Freddy Rybom AS | Wholesale & retail | 1979 |
| Frednor AS | Hospitality | 2015 |
| Fredrick AS | Real estate | 2010 |
| Fredrik Flodin AS | Information & communication | 2016 |
| Fredrik Støle AS | Arts & recreation | 2022 |
| Fredriksborg AS | Real estate | 1991 |
| Fredriksborg Eiendom 1 AS | Real estate | 2024 |
| Fredriksborg Eiendom 2 AS | Real estate | 2024 |
| Fredriksborg Eiendom 3 AS | Real estate | 2024 |
| Fredriksborg Eiendom 4 AS | Real estate | 2018 |
| Fredriksborg Eiendom AS | Real estate | 1969 |
| Fredriksborg Investor AS | Real estate | 2013 |
| Fredriksborg Utvikling AS | Real estate | 2009 |
| Fredriksstad Blad AS | Information & communication | 1888 |
| Fredrikstad Amcar Club AS | Real estate | 2006 |
| Fredrikstad Apartments AS | Real estate | 2013 |
| Fredrikstad Assuranse AS | Financial services | 2008 |
| Fredrikstad Auto AS | Other services | 2022 |
| Fredrikstad Autocenter AS | Wholesale & retail | 2011 |
| Fredrikstad Autosalg AS | Wholesale & retail | 2020 |
| Fredrikstad Barbershop AS | Other services | 2026 |
| Fredrikstad Begravelsesbyrå Klemet Johansen AS | Other services | 1992 |
| Fredrikstad Begravelsesservice Klemet Johansen AS | Other services | 2010 |
| Fredrikstad Bil Og Henger Service AS | Other services | 2025 |
| Fredrikstad Bilservice AS | Other services | 2012 |
| Fredrikstad Bilskade Og Lakk AS | Other services | 2001 |
| Fredrikstad Blikkenslagerverksted AS | Construction | 2010 |
| Fredrikstad Blomsterverksted - Guttas Blomster Fredrikstad AS | Wholesale & retail | 2016 |
| Fredrikstad Boligutleie AS | Real estate | 2018 |
| Fredrikstad Broa AS | Other services | 2024 |
| Fredrikstad Bruktbil AS | Wholesale & retail | 2019 |
| Fredrikstad Bruktbil Eiendom AS | Real estate | 2019 |
| Fredrikstad Catering & Selskapsmat AS | Hospitality | 2025 |
| Fredrikstad Damputstyr AS | Wholesale & retail | 2020 |
| Fredrikstad Dyrehospital AS | Professional & scientific | 2012 |
| Fredrikstad Eiendom Service Og Bolig Utvikling AS | Construction | 2012 |
| Fredrikstad Eiendomskontor AS | Real estate | 1981 |
| Fredrikstad Eiendomsmegling AS | Real estate | 2021 |
| Fredrikstad Energi AS | Energy | 1994 |