| Heer Invest AS | | 2022 |
| Heia Holding AS | Manufacturing | 2022 |
| Hejoka AS | | 2023 |
| Heller Bil AS | Other services | 2026 |
| Heltsjef AS | Professional & scientific | 2018 |
| Henost AS | Construction | 2015 |
| Hestehelse AS | Agriculture & fishing | 2018 |
| Hestenes & Pedersen Ans Pedagogiske Konsulenter. | | 1988 |
| HH Entreprenørtjenester AS | Construction | 2010 |
| HHH Holding AS | Construction | 2013 |
| Hit AS | Wholesale & retail | 1982 |
| Hko Invest AS | | 2021 |
| Hldng AS | Information & communication | 2013 |
| HMT Invest AS | Real estate | 2022 |
| Holms Dreieverksted AS | Manufacturing | 2021 |
| Homstvedt Maskinlag SA | Agriculture & fishing | 1996 |
| Honic Holding AS | Wholesale & retail | 2020 |
| Hreset AS | Information & communication | 2021 |
| Hso Eiendom AS | Real estate | 2016 |
| Hsy Invest AS | | 2025 |
| HT Byggservice AS | Construction | 2019 |
| HTP Entreprenør AS | Construction | 2023 |
| Huseby Eiendom Og Rådgivning AS | Construction | 1997 |
| Huseby Glass & Bygg AS | Construction | 2025 |
| Hybris Invest AS | | 2020 |
| Iag Eiendom AS | Real estate | 2004 |
| Idehus Østfoldbygg AS | Construction | 2006 |
| Imer AS | Professional & scientific | 1994 |
| Indre Østfold Drift Og Eiendom AS | Real estate | 2014 |
| Indre Østfold Elektro AS | Construction | 2003 |
| Indre Østfold Fysiosenter AS | Health & social care | 2022 |
| Indre Østfold Hotelldrift AS | Hospitality | 1993 |
| Indre Østfold Maskinsenter AS | Wholesale & retail | 2008 |
| Indre Østfold Taktekking AS | Construction | 2021 |
| Ingar Jensen AS | Administrative & support | 2005 |
| Ingmar Invest AS | Financial services | 2013 |
| Ingvar Svenssons Bygg I Hassleholm Aktiebolag | Construction | 2001 |
| Inside Creative AS | Information & communication | 2020 |
| Inside Sport AS | Professional & scientific | 2013 |
| Invest Langnes AS | | 2023 |
| Io Holding AS | Professional & scientific | 2015 |
| IT Bygg Og Transportservice AS | Transport & logistics | 2010 |
| Jaré AS | Wholesale & retail | 2026 |
| Jasa AS | Other services | 2025 |
| Je-Ro Invest AS | | 2019 |
| Jel Holding AS | | 2026 |
| Jelsnes Flis Og Bad AS | Construction | 2017 |
| Jera Invest AS | | 2007 |
| Ji Solberg Holding AS | Professional & scientific | 2019 |
| Jon Grevæg Invest AS | Other services | 2014 |
| Jona/S AS | Professional & scientific | 2024 |
| Josan Eiendom & Utleie AS | Real estate | 2023 |
| JS Bil Og Eiendom AS | Wholesale & retail | 2026 |
| Juna Eiendom AS | Real estate | 2016 |
| Jørgensen Auto AS | Other services | 2025 |
| K.Tørres Holding AS | | 2022 |
| Kakelugnsmakaren I Värmland Staffan Forsstrøm | Wholesale & retail | 1997 |
| Kalvehagen AS | Real estate | 2005 |
| Kama Renhold AS | Administrative & support | 2022 |
| Kattan Consulting Service AS | Professional & scientific | 2021 |
| Ke Entreprenør AS | Construction | 2013 |
| Kejomy Holding AS | Real estate | 2019 |
| KFM Holding AS | | 2005 |
| Kherland Holding AS | | 2024 |
| Kiosken Salg Og Service Da | Wholesale & retail | 2005 |
| Kjøkken Huset AS | Wholesale & retail | 2005 |
| Klever AS | Professional & scientific | 2004 |
| Klienter På Nett AS | Education | 2026 |
| Korsetten AS | Wholesale & retail | 2019 |
| Krog & S Eiendom AS | Real estate | 2020 |
| Krog Bolig AS | Real estate | 2008 |
| Krog Invest AS | | 2023 |
| Krog Maskin & Transport AS | Construction | 2026 |
| Krog Trelast AS | Wholesale & retail | 2024 |
| Krogstadfossen Mølle AS | Real estate | 1985 |
| Kunsthub AS | Wholesale & retail | 2011 |
| Kus MC Østfold AS | Wholesale & retail | 2018 |
| La Casa Grill AS | Hospitality | 2022 |
| La Mòss AS | Hospitality | 2015 |
| Laas Consulting AS | Professional & scientific | 2025 |
| Langebrekke Grustak AS | Mining & quarrying | 1998 |
| Laplace AS | Real estate | 1999 |
| Lendesign AS | Professional & scientific | 2024 |
| Leon Bygg AS | Construction | 2015 |
| Lie Bedriftservice AS | Professional & scientific | 1991 |
| Lillåsen AS | Real estate | 2011 |
| Linnéa Natur- Og Gårdsbarnehage AS | Education | 2022 |
| Lintho Maskin AS | Wholesale & retail | 2006 |
| Lintho Regnskap AS | Professional & scientific | 2022 |
| Lintho Steinmiljø AS | Construction | 2007 |
| Loym AS | Information & communication | 2014 |
| LS Bygg Og Utleie AS | Real estate | 2023 |
| Lucrum AS | Real estate | 1997 |
| Ludde Invest AS | Real estate | 2015 |
| Lundeby Og Engen Eiendom AS | Real estate | 2017 |
| Luthagen AS | Information & communication | 2021 |
| Lux Horses AS | Agriculture & fishing | 2018 |
| Lytomt Gård Da | Agriculture & fishing | 2026 |
| Løken Invest AS | Real estate | 2005 |
| Løvfald Arkitekter AS | Professional & scientific | 2002 |