| Kasjotten AS | Real estate | 2005 |
| Kaskad Ltd | Arts & recreation | 2022 |
| Kaskrantz AS | Real estate | 2025 |
| Kasor Invest AS | Financial services | 2005 |
| Kasper Hauge AS | Wholesale & retail | 2025 |
| Kasper Wischmann Software AS | Information & communication | 2020 |
| Kassa Til Karl AS | Financial services | 2016 |
| Kassane Eigedom AS | Real estate | 2017 |
| Kassarull AS | Wholesale & retail | 2021 |
| Kasserolle AS | Hospitality | 2019 |
| Kasserollen Restaurantdrift AS | Hospitality | 2001 |
| Kassøya Invest AS | Real estate | 2019 |
| Kast Finans AS | Real estate | 2016 |
| Kast Invest AS | | 2005 |
| Kastadalselvi Kraftverk AS | Energy | 2025 |
| Kastanjen Eiendom AS | Real estate | 1999 |
| Kastanni AS | | 2026 |
| Kaste AS | Professional & scientific | 2014 |
| Kastel AS | Wholesale & retail | 2012 |
| Kastellet Dagligvare AS | Wholesale & retail | 2005 |
| Kastellet Eiendom AS | Real estate | 1979 |
| Kastellet Import AS | Wholesale & retail | 2021 |
| Kastellhagen Interiør AS | Wholesale & retail | 2019 |
| Kastellhagen Prosjekt AS | Wholesale & retail | 2005 |
| Kastellvegen Panorama AS | Real estate | 2016 |
| Kastellveien 19 AS | Real estate | 2022 |
| Kastler/Skjeseth Architects AS Mnal | Professional & scientific | 2015 |
| Kasto Holding AS | Financial services | 2014 |
| Kastratis Renholdsservice AS | Administrative & support | 2012 |
| Kastriot Kapital AS | | 2024 |
| Kastro AS | Real estate | 2015 |
| Kastum Management AS | Professional & scientific | 2008 |
| Kasu AS | Manufacturing | 1988 |
| Kasy AS | Health & social care | 1970 |
| Kat Holding AS | | 2024 |
| Kat-Refining AS | Wholesale & retail | 2016 |
| Kata Corporation Holding Limited | | 2022 |
| Kata Corporation Limited | Wholesale & retail | 2021 |
| Kata Holding AS | | 2025 |
| Kata Invest AS | Professional & scientific | 2022 |
| Katakomben Da | Wholesale & retail | 2015 |
| Katalyse AS | Information & communication | 2024 |
| Katalyst Data Management LP Nuf | Information & communication | 2026 |
| Katalyst Konsult AS | Education | 2024 |
| Katalyzator AS | Professional & scientific | 2018 |
| Katalyzator Holding AS | Wholesale & retail | 2003 |
| Katan Holding AS | Information & communication | 2014 |
| Katan Software AS | Information & communication | 2016 |
| Katana Invest AS | Financial services | 2016 |
| Katapult Accelerator AS | Financial services | 2016 |
| Katapult Accelerator Follow-On Fund AS | Financial services | 2017 |
| Katapult Accelerator Fund 2 AS | Financial services | 2017 |
| Katapult Accelerator Fund 3 AS | Financial services | 2018 |
| Katapult Accelerator Fund 4 AS | Financial services | 2019 |
| Katapult Accelerator SPV 1 AS | Financial services | 2017 |
| Katapult Climate Fund 1 AS | Financial services | 2021 |
| Katapult Climate Fund 3 AS | Financial services | 2022 |
| Katapult DB1 GP AS | | 2019 |
| Katapult DB2 GP AS | | 2026 |
| Katapult Food AS | Professional & scientific | 2019 |
| Katapult Holdco AS | Real estate | 2017 |
| Katapult Holding AS | | 2023 |
| Katapult Impact Platform AS | Administrative & support | 2020 |
| Katapult Ocean AS | Financial services | 2018 |
| Katapult Ocean Deep Blue Fund 1 AS | Financial services | 2022 |
| Katapult Ocean Deep Blue Fund 2 AS | Financial services | 2026 |
| Katapult Ocean Fund 1 AS | Financial services | 2018 |
| Katapult Ocean Fund 2 AS | Financial services | 2018 |
| Katapult Ocean Fund 3 AS | Financial services | 2021 |
| Katapult Ocean Holding AS | | 2023 |
| Katapult Seed Fund 1 AS | Financial services | 2022 |
| Katapult X AS | Administrative & support | 2017 |
| Katarina Caspersen AS | Arts & recreation | 2025 |
| Katarina Holding AS | Other services | 2013 |
| Katatonic Invest AS | Real estate | 2012 |
| Katerina Invest AS | Other services | 2016 |
| Katerås Invest AS | | 2026 |
| Kath AS | Real estate | 2005 |
| Kath Holding AS | | 2026 |
| Katharos Ans | Other services | 1996 |
| Kathimar Kapital AS | | 2025 |
| Kathinka Holding AS | Wholesale & retail | 2020 |
| Kathinka Knudtzon AS | | 2005 |
| Kathrine Quilte Stue Oslo AS | Wholesale & retail | 1998 |
| Kathrine Thorborg AS | Arts & recreation | 2025 |
| Kathrine Veum AS | Financial services | 2009 |
| Kathuria Invest AS | | 2019 |
| Katinas AS | Real estate | 1990 |
| Katja Van Etten Jarem AS | Arts & recreation | 2026 |
| Katla AS | Hospitality | 2017 |
| Katnosa Aksjeselskap | Financial services | 2017 |
| Kato Presterud Invest AS | Information & communication | 2001 |
| Katoj AS | Financial services | 2005 |
| Katona Rekruttering AS | Administrative & support | 2026 |
| Katra AS | Professional & scientific | 2007 |
| Katrin Invest AS | | 2019 |
| Katrina Urbanik AS | Professional & scientific | 2015 |
| Katrine K AS | Professional & scientific | 1998 |
| Katron AS | Real estate | 2024 |
| Katsuline Invest AS | Professional & scientific | 2017 |