| Kjøpmannsgt 59 Ans | Real estate | 1988 |
| Kjøpmannsgt. 29 AS | Construction | 2014 |
| Kjøpmannsgt. 57 AS | Real estate | 2007 |
| Kjøpmannsgt. 9 Klenodiet AS | Real estate | 2006 |
| Kjøtteinsvegen 71 AS | Real estate | 2006 |
| Kk-Holding AS | Real estate | 2018 |
| Kkaa Invest AS | Health & social care | 2022 |
| Kkaa Kjeveort AS | Health & social care | 2025 |
| KKS Invest AS | Real estate | 2021 |
| Klafter AS | Real estate | 2021 |
| Klarmedia AS | Professional & scientific | 2023 |
| Klartek Da | Information & communication | 2025 |
| Klatrebedriften AS | Information & communication | 2017 |
| Kleins AS | Wholesale & retail | 1980 |
| Kleins Azur AS | Wholesale & retail | 2002 |
| Kleins Byhaven AS | Wholesale & retail | 2015 |
| Kleins City AS | Wholesale & retail | 2015 |
| Kleins Dronningensgt. 38 AS | Real estate | 2015 |
| Kleins Karat AS | Professional & scientific | 2019 |
| Kleins Peak AS | Wholesale & retail | 2015 |
| Kleins Sirkus AS | Wholesale & retail | 2015 |
| Kleins Sixpence AS | Professional & scientific | 2015 |
| Kleinsky AS | | 2025 |
| Klempe Holding AS | | 2021 |
| Klempe Og Dons AS | Hospitality | 2020 |
| Kleppestø Næringseiendom AS | Real estate | 2005 |
| Klett Utvikling AS | Real estate | 2006 |
| Klettsletta Invest AS | Real estate | 2021 |
| Kleveland's Utemiljø AS | Administrative & support | 2006 |
| Klevstuen Holding AS | Professional & scientific | 2020 |
| Klewebeauty AS | Other services | 2024 |
| Klikk Invest AS | Health & social care | 2021 |
| Klima Og Kuldeteknikk A/S | Construction | 1988 |
| Klimafinans AS | Professional & scientific | 2020 |
| Klingenberggården AS | Real estate | 2024 |
| Klinikk 5 Trondheim AS | Health & social care | 2006 |
| Klinikk Askim AS | Health & social care | 2010 |
| Klinikk Askim Sentrum AS | Health & social care | 2026 |
| Klinikk Bølgen AS | Health & social care | 2023 |
| Klinikk Foss AS | Health & social care | 2017 |
| Klinikk Isis T Strand AS | Health & social care | 1987 |
| Klinikk Kognito AS | Health & social care | 2019 |
| Klinikk Meadow AS | Health & social care | 2023 |
| Klinikk Speilet AS | Real estate | 2016 |
| Klinikk Trondheim AS | Health & social care | 2000 |
| Klinikk Øre-Nese-Hals AS | Health & social care | 2023 |
| Klinikk Øyeblikk AS | Health & social care | 2007 |
| Klipp Fiction AS | Information & communication | 2025 |
| Klipp Og Lim Holding AS | Professional & scientific | 2005 |
| Klipp Og Lim Media AS | Professional & scientific | 2000 |
| Klipra Eiendom AS | Real estate | 2003 |
| KLK Holding AS | | 2025 |
| KLN Invest AS | Real estate | 2020 |
| Klockwork IT AS | Information & communication | 2021 |
| Klok Av Skaaden AS | | 2026 |
| Klokkesamleren Da | Wholesale & retail | 2024 |
| Klokkesvingen AS | Construction | 2021 |
| Klomaten Holding AS | | 2021 |
| Klondike Mining AS | Information & communication | 2022 |
| Klostergata 38A AS | Real estate | 2017 |
| Klostergata 57 AS | Real estate | 2007 |
| Klostergaten Holding AS | Professional & scientific | 2020 |
| Klostergt 32 Trondheim AS | Real estate | 2007 |
| KLOSTERGT.12 AS | Real estate | 2015 |
| KLP Banken AS | Financial services | 2009 |
| KLP Bassengtomten AS | Real estate | 2004 |
| KLP Boligkreditt AS | Financial services | 2013 |
| KLP Dybdahlsgården AS | Real estate | 2012 |
| KLP Eiendom Trondheim AS | Real estate | 1984 |
| KLP Eiendom Trondheim Holding AS | Real estate | 1986 |
| KLP Eiendomsdrift Trondheim AS | Real estate | 1997 |
| KLP Ferjemannsveien 10 AS | Real estate | 2004 |
| KLP Gryta AS | Real estate | 2006 |
| KLP Haakon Vii Gate 6 AS | Real estate | 1984 |
| KLP Klæbuveien AS | Real estate | 2007 |
| KLP Kommunekreditt AS | Financial services | 2009 |
| KLP Næringsbygg Trondheim AS | Real estate | 2006 |
| KLP Peter Egges Plass 2 AS | Real estate | 2006 |
| KLP Ranheimsveien 10 AS | Real estate | 1918 |
| KLP Ranheimsveien 9 AS | Real estate | 1999 |
| KLP Sandfærhus AS | Real estate | 1984 |
| KLP Skipsbygget AS | Real estate | 2004 |
| KLP Sluppen AS | Real estate | 2006 |
| KLP Teknobyen AS | Real estate | 2006 |
| KLP Tempeveien 22 AS | Real estate | 2008 |
| KLP Verkskontorene AS | Real estate | 2004 |
| KLP Zander Kaaes GT. 7 AS | Real estate | 2013 |
| KLP Østre Rosten 8 AS | Real estate | 1996 |
| Klungerbo Holding AS | | 2021 |
| Klungerbo Invest AS | | 2021 |
| Klungerbo Samdrift Da | Agriculture & fishing | 2009 |
| Klure Holding AS | | 2023 |
| Klyra Kristansand AS | Other services | 2026 |
| Klæbo Media AS | Professional & scientific | 2017 |
| Klæbu Energipark AS | Real estate | 2026 |
| Klæbu Panorama Utbygging AS | Real estate | 2016 |
| Klæbutorget BT2 AS | Real estate | 2018 |
| Klæbuveien 138 AS | Real estate | 1992 |
| Klæbuveien 145 AS | Households | 1953 |
| Klæbuveien 194 AS | Real estate | 2007 |