| Fredrikstad Flyttebyrå AS | Transport & logistics | 2001 |
| Fredrikstad Form & Farge Ans | Wholesale & retail | 1990 |
| Fredrikstad Foto AS | Wholesale & retail | 2017 |
| Fredrikstad Gass & VVS AS | Construction | 2013 |
| Fredrikstad Handelsstands Selskapslokaler AS | Hospitality | 2010 |
| Fredrikstad HD Service Ans | Other services | 1994 |
| Fredrikstad Hotelldrift AS | Hospitality | 2013 |
| Fredrikstad Import Da | | 1994 |
| Fredrikstad Kino AS | Information & communication | 2026 |
| Fredrikstad Lungeklinikk AS | Health & social care | 2026 |
| Fredrikstad Marina AS | Real estate | 2012 |
| Fredrikstad Marina Drift AS | Transport & logistics | 2020 |
| Fredrikstad Mat AS | Wholesale & retail | 2013 |
| Fredrikstad Medie Verksted AS | Professional & scientific | 2009 |
| Fredrikstad Osteopati AS | Health & social care | 2005 |
| Fredrikstad Parkering AS | Real estate | 1995 |
| Fredrikstad Piercing Og Tatovering AS | Other services | 2021 |
| Fredrikstad Pizza & Grill AS | Real estate | 2007 |
| Fredrikstad Pizza AS | Hospitality | 2025 |
| Fredrikstad Renhold AS | Administrative & support | 2025 |
| Fredrikstad Revisjon AS | Professional & scientific | 2018 |
| Fredrikstad Rygg Og Leddsenter AS | Health & social care | 2009 |
| Fredrikstad Shipping Co AS | Real estate | 1915 |
| Fredrikstad Skade Og Lakk AS | Other services | 2020 |
| Fredrikstad Specsavers AS | Wholesale & retail | 2016 |
| Fredrikstad Taxi AS | Transport & logistics | 2021 |
| Fredrikstad Tennisarena AS | Arts & recreation | 2026 |
| Fredrikstad Trafikkskole AS | Education | 2021 |
| Fredrikstad Trening Og Helse AS | Education | 2015 |
| Fredrikstad Utvikling AS | Real estate | 2014 |
| Fredrikstad Vask & Renseri AS | Other services | 2021 |
| Fredrikstad Øyelegekontor AS | Health & social care | 2015 |
| Fredrikstad Øyelegesenter AS | Health & social care | 2025 |
| Fredrikstadadvokatene AS | Real estate | 2000 |
| Fredrikstadguttane AS | Arts & recreation | 2020 |
| Freeway AS | Hospitality | 2023 |
| Fremskridt 10 Eiendom AS | Real estate | 2010 |
| Fremskridt 4 AS | Real estate | 2018 |
| Fremtrinn AS | | 2024 |
| Fresko Eiendom AS | Real estate | 2015 |
| Frisk Og Rask Klinikken AS | Health & social care | 2020 |
| Frisør Ronny Pettersen AS | Other services | 2012 |
| Frisør Shawn Emilie Veibye AS | Other services | 2022 |
| Frisørdrift AS | Other services | 2007 |
| Frisørmester Vidar Jacobsen AS | Other services | 1978 |
| Frithjof Paulsen AS | Wholesale & retail | 2001 |
| Frode Kværneng AS | Professional & scientific | 2003 |
| Fromt Bedrag Da Siw a Bech K Anniken Paulsen Gade Brit Langvik | Arts & recreation | 2000 |
| FRS - Holding AS | | 2017 |
| Fryd Frisører AS | Other services | 2017 |
| Frøydis Olsen AS | Real estate | 2005 |
| Fuel Effect Norway Ans | Wholesale & retail | 2000 |
| Fun Fredrikstad AS | Wholesale & retail | 2022 |
| Fungybar AS | Manufacturing | 2024 |
| Furunåla Bygg AS | Construction | 2025 |
| Futma AS | Wholesale & retail | 1987 |
| Fys AS | Health & social care | 2015 |
| Færd Holding AS | Real estate | 2012 |
| G Lund Invest AS | | 2012 |
| G-Invest AS | | 1982 |
| G.G. Holding AS | Financial services | 2005 |
| G.Glass AS | Manufacturing | 2015 |
| G.M.C Eiendom AS | Real estate | 2005 |
| Gaarder Sykkelsport AS | Wholesale & retail | 1987 |
| Galadriel Invest AS | Health & social care | 2010 |
| Galloppen AS | Real estate | 2020 |
| Gamle Ålevei Eiendom AS | Real estate | 2021 |
| Gamlebyen Vertshus AS | Hospitality | 2013 |
| Gardina Sigfrid Jensen Bjørg Brusevold Ans | Wholesale & retail | 1984 |
| Garnhuset Fredrikstad AS | Wholesale & retail | 2006 |
| Gars Eiendom AS | | 2000 |
| Gattermann Eiendomsforvaltning AS | Real estate | 1989 |
| Gbi Invest AS | Real estate | 2005 |
| Gbl-Holding AS | | 2022 |
| Geir Ringstad Holding AS | Wholesale & retail | 2015 |
| Geisha Sushi Japan Fredrikstad AS | Hospitality | 2022 |
| Get Entreprenør AS | Construction | 2017 |
| Geto Forvaltning AS | Real estate | 2011 |
| Gjerdsbakk Kiropraktikk AS | Health & social care | 2018 |
| GK Autosave AS | Other services | 2025 |
| Glansbil AS | Wholesale & retail | 2025 |
| Glass Og Fasade Design AS | Construction | 2023 |
| Glass Og Ramme Fredrikstad AS | Manufacturing | 2016 |
| Glassolsen Eiendom AS | Real estate | 2021 |
| Glassolsen Holding AS | Manufacturing | 2013 |
| Glassteknikk AS | Construction | 2022 |
| Glemmen Eiendom 5 AS | Real estate | 2009 |
| Glemmen Gård Eiendom AS | Real estate | 2009 |
| Glemmen Gård Utleiebygg AS | Real estate | 2009 |
| Glemmen Holding AS | Real estate | 2009 |
| Glemmen Invest AS | Real estate | 2025 |
| Glemmen Tomt 31 AS | Real estate | 2017 |
| Glemmen Tomt 7 AS | Real estate | 2009 |
| Glemmen Tomt Felt B AS | Real estate | 2023 |
| Glenn Helgesen Invest AS | Real estate | 2008 |
| Glitter AS | Wholesale & retail | 1994 |
| Global Aid Resource AS | Wholesale & retail | 2015 |
| Global Resource AS | Wholesale & retail | 2025 |
| Glomma Fysioterapi Ans | Health & social care | 1988 |
| Glomma Legesenter AS | Health & social care | 2006 |