| Hilde Hem Holding AS | Financial services | 2017 |
| Hitterdal Holding AS | Construction | 2020 |
| Hitterdal Service AS | Hospitality | 2021 |
| Hjemmebrent Kaffe AS | Wholesale & retail | 2024 |
| Hjuksebø Dekkhotell AS | Other services | 2015 |
| Hjuksebø Invest AS | Financial services | 2005 |
| Hjuksebø Montessoriskole SA | Education | 2013 |
| Hjuksebø Næringspark AS | Real estate | 2013 |
| HK Handel AS | Hospitality | 2014 |
| HN Bil AS | Wholesale & retail | 2018 |
| Honning På Tungen AS | Agriculture & fishing | 2026 |
| HR Path Norway AS | Information & communication | 2026 |
| HS Regnskap AS | Professional & scientific | 2010 |
| Hus Og Hytte Laft AS | Wholesale & retail | 2016 |
| Hustveitlåven AS | Arts & recreation | 2017 |
| HW Holding AS | Wholesale & retail | 2005 |
| Hybridized AS | Manufacturing | 2022 |
| Hydroparken AS | Real estate | 2004 |
| Hykkerud Invest AS | | 2023 |
| Häxer Da | Arts & recreation | 2023 |
| Håkon Bakken AS | | 2020 |
| Håndverkringen AS | Construction | 2017 |
| Håvards Holding AS | | 2025 |
| Høgås Eiendomsutvikling AS | Real estate | 2001 |
| Høgås Equipment AS | Construction | 2019 |
| Høgås Invest AS | | 2008 |
| Høgås Næringspark AS | Real estate | 2021 |
| Høgås Solkraft AS | Energy | 2026 |
| Høgås Teknologipark AS | Real estate | 1998 |
| Idea Barnehage Kongsberg AS | Education | 2020 |
| Idea Barnehage Notodden AS | Education | 2022 |
| Idea Kompetanse Arbeid Og Inkludering AS | Health & social care | 2020 |
| Idea Kompetanse AS | Health & social care | 1991 |
| Idea Kompetanse Jobb Og Utvikling AS | Health & social care | 2020 |
| Idea Mekanisk AS | Health & social care | 2020 |
| Idrettsparken AS | Real estate | 2023 |
| Ihz AS | Administrative & support | 2023 |
| Il Takst AS | Real estate | 1994 |
| Impel AS | Professional & scientific | 2022 |
| Ing Thor H Jacobsen AS | Construction | 1986 |
| Inger Flood Eiendom AS | Real estate | 2021 |
| Innogrønn AS | Real estate | 2014 |
| Intech Group AS | Manufacturing | 2008 |
| Investment Group AS | Construction | 2017 |
| Irmat AS | Water & waste | 2002 |
| Irmat Ressurs AS | Water & waste | 2019 |
| Isaksen Og Landvik AS | Real estate | 1961 |
| Itfakultetet AS | Education | 2020 |
| Itho Eiendom AS | Real estate | 2012 |
| Itum Notodden AS | Information & communication | 2007 |
| J Løvheim Maskin AS | Wholesale & retail | 1983 |
| J O Drift AS | Wholesale & retail | 2017 |
| J O Holding AS | Real estate | 2017 |
| J. I. Heimdal Entreprenør AS | Construction | 2009 |
| J.A. Invest AS | Financial services | 2005 |
| Jakobsson Rail AS | Administrative & support | 2023 |
| Jama Service AS | Professional & scientific | 2014 |
| Jamtveit AS | Construction | 2014 |
| Jamtveit Entreprenør AS | Construction | 2022 |
| Jamtveit Rental AS | Administrative & support | 2024 |
| Jan Tore Finnekåsa AS | Construction | 2007 |
| Je Solberg Holding AS | | 2021 |
| Jensås Invest AS | Real estate | 2018 |
| Jkbakk AS | | 2020 |
| Jke Design Notodden AS | Wholesale & retail | 2018 |
| Jl-Holding AS | | 2020 |
| John Seljord AS | Transport & logistics | 1989 |
| John Seljord Holding AS | Real estate | 2005 |
| JPT Utvikling AS | | 2005 |
| Jrbs Holding AS | Wholesale & retail | 2005 |
| JS Support AS | Construction | 2020 |
| JT Bil AS | Wholesale & retail | 2016 |
| Juggel Og Juveler AS | Wholesale & retail | 2019 |
| Just Flowers AS | Arts & recreation | 2025 |
| JVZ Kvalitet AS | Construction | 2019 |
| K-Lie AS | | 2021 |
| Kaasa Bruktbil AS | Wholesale & retail | 2024 |
| Kaasa Transport AS | Transport & logistics | 1991 |
| Kaki International Trading Corporation AS | Real estate | 2012 |
| Kalbekkdalen Invest AS | Real estate | 2020 |
| Karma Notodden AS | Wholesale & retail | 2012 |
| Kasland Trafikkskole Notodden AS | Education | 2023 |
| Kelbekk Holding AS | | 2024 |
| Keytouch Technology AS | Manufacturing | 2005 |
| Kinsarvik Naturkost Notodden AS | Wholesale & retail | 2004 |
| Kivle AS | Construction | 1996 |
| Kjello Holding AS | Real estate | 2016 |
| Kjerringrokk B&B AS | Hospitality | 2024 |
| Kjetil Holding Johansen AS | | 2026 |
| Kjosvold Eiendom AS | Real estate | 2019 |
| Kjosvold Holding AS | Real estate | 2005 |
| Kjøretøy AS | Wholesale & retail | 2018 |
| Kolbjørnsrud Invest AS | | 2020 |
| Kongsberg Brønnboring AS | Administrative & support | 2017 |
| Kongsgaard Begravelsesbyrå AS | Other services | 2020 |
| Kongsvold Eiendom AS | Construction | 2025 |
| Konsert-Service AS | Arts & recreation | 2007 |
| KP Entreprenør AS | Construction | 2019 |
| Krb-Bygg AS | Construction | 2016 |
| Kreos AS | Professional & scientific | 2023 |