| Juli AS | Real estate | 2023 |
| Junge Og Bauger | | 1987 |
| Juttul AS | Real estate | 2021 |
| Jux AS | Real estate | 2012 |
| Jørgen Dahl Holding AS | | 2021 |
| Jørgen Thoresen AS | Other services | 2006 |
| K D Fjeldstad AS | Professional & scientific | 1978 |
| K Myhra Holding AS | | 2026 |
| K Solution AS | Construction | 2021 |
| K&N Project AS | Professional & scientific | 2025 |
| K. Digre Holding AS | | 2016 |
| K.M. Storegjerde AS | Real estate | 2009 |
| K.O.H Invest Holding AS | Financial services | 2015 |
| Kadens AS | Wholesale & retail | 2013 |
| Kah 1-3 Invest AS | | 2020 |
| Kalager Invest AS | | 2025 |
| Kaliber Gym Hønefoss AS | Arts & recreation | 2016 |
| Kallerud Handelspark AS | Real estate | 2008 |
| Kallerudlia 5 AS | Real estate | 2005 |
| Kambo Butikkeiendom AS | Real estate | 2007 |
| Kamyab Holding AS | | 2020 |
| Karate Invest AS | | 2011 |
| KARI SMITH ANS Kari og Sven-Ole Smith | | 1989 |
| Karibrenna Strøm SA | Energy | 2024 |
| Karibrenna Utbygging Vann SA | Construction | 2024 |
| Karibrenna Vanndrift AS | Water & waste | 2024 |
| Karl a Haraldsen 1 AS | Financial services | 2020 |
| Karma-G AS | Financial services | 2021 |
| Kartverksveien 9 Eiendom AS | Real estate | 1998 |
| Kastet Eiendom AS | Hospitality | 1990 |
| Kathrines Hudklinikk AS | Other services | 2020 |
| KDS Invest AS | | 2022 |
| KEFRO IMPORT ANS Kate Fossheim Frode Fossheim | | 1988 |
| Key Systems AS | Information & communication | 2021 |
| KG Prosjektering Da | Professional & scientific | 2006 |
| KG10 Eiendom AS | Real estate | 2023 |
| Khalles Corner Hønefoss AS | Hospitality | 2025 |
| Kikko Sushi AS | Hospitality | 2016 |
| Kikut Invest AS | Professional & scientific | 2005 |
| Kilemoen Eiendom AS | Real estate | 2003 |
| Kilemoen Invest AS | Real estate | 2001 |
| Kilemokroken 1 AS | Real estate | 2022 |
| Kilemokroken 19 AS | Real estate | 2022 |
| Kilemokroken 9 S12 AS | Real estate | 2024 |
| Kilemokroken 9 S16 AS | Real estate | 2024 |
| Kilemokroken 9 S17 AS | Real estate | 2024 |
| Kilemokroken 9 S18 AS | Real estate | 2024 |
| Kilemokroken 9 S19 AS | Real estate | 2024 |
| Killingtjern AS | Real estate | 2013 |
| Killingtjernveien M. FL. SA | Real estate | 1955 |
| Kinahavet AS | Hospitality | 2002 |
| Kindberg & Kristiansen Elektriske AS | Construction | 2006 |
| Kingsley AS | Hospitality | 2023 |
| Kirkegaten 7 Ans | Real estate | 2002 |
| Kirkekrysset AS | Real estate | 2006 |
| Kirkenær Handelseiendom AS | Real estate | 2018 |
| Kjell Fredriksen AS | Real estate | 2024 |
| Kjeni Eiendom AS | Real estate | 2016 |
| Kjetil Skrede's Virke AS | Construction | 2020 |
| Kjøkkendrift No 1 Kuben AS | Wholesale & retail | 2017 |
| Kjøtt Huset AS | Wholesale & retail | 2025 |
| KKB Eiendom AS | Wholesale & retail | 2013 |
| Klefier Huus AS | Real estate | 2007 |
| Klefier Palé AS | Real estate | 2014 |
| Klekken Butikkeiendom AS | Real estate | 2014 |
| Klekken Gartneri AS | Agriculture & fishing | 2012 |
| Klekken Mathus AS | Wholesale & retail | 2010 |
| Klekkenveien 164 AS | Real estate | 2021 |
| Klemma Invest AS | Construction | 2005 |
| Klinikk Blix AS | Health & social care | 2017 |
| Klippen Kapital AS | | 2015 |
| Klokkerlia Panorama AS | Real estate | 2022 |
| Klokkerlia Utvikling 2 AS | Real estate | 2018 |
| Klækken Hotell Ans | Hospitality | 1985 |
| Klækken Hotell AS | Hospitality | 1985 |
| KMS Holding AS | | 2005 |
| KN Håndverk AS | Construction | 2017 |
| Knut Strand Invest AS | Professional & scientific | 2005 |
| Komplett Revisjon AS | Professional & scientific | 2019 |
| Kongsberg Butikkeiendom AS | Real estate | 2008 |
| Kongsvinger Handelseiendom AS | Real estate | 2007 |
| Konkret Support AS | Professional & scientific | 2008 |
| Kontoreiendom AS | Real estate | 2011 |
| Kontorinteriør Ringerike AS | Wholesale & retail | 2009 |
| Kontormiljø Ringerike AS | Wholesale & retail | 2003 |
| Kopi - Trans AS | Wholesale & retail | 2009 |
| Korsegårdsveien 22 AS | Real estate | 2005 |
| Kosekroken Kafé AS | Hospitality | 2026 |
| Kosiur Restaurant Drift AS | Hospitality | 2017 |
| Kraft Pizzeria AS | Hospitality | 2023 |
| Kraft Pizzeria Hønefoss AS | Hospitality | 2021 |
| Kraftgutta AS | Manufacturing | 2023 |
| Kraftriket AS | Energy | 1995 |
| Kran & Tungbil Service AS | Manufacturing | 2015 |
| Kran Eiendom AS | Real estate | 2016 |
| Kreativ Bygg AS | Construction | 2024 |
| Kreativ Communication AS | Information & communication | 2012 |
| Kremmertorvet Sport Og Fritid AS | Wholesale & retail | 2013 |
| Kringen Collectibles AS | Wholesale & retail | 2026 |
| Kringen Invest AS | Wholesale & retail | 2025 |