| Kvothe Oy | Construction | 2025 |
| Kwai Kei Oy | Hospitality | 1996 |
| Kwayyis International Oy | Professional & scientific | 1989 |
| Kwizie Oy | Information & communication | 2023 |
| Kwok Keung Oy | Hospitality | 1994 |
| Ky Asianajotoimisto Herbert Gumpler Advokatbyrå Kb | Professional & scientific | 1987 |
| Ky Björn Lindqvist Kb | | 1981 |
| Ky Cinemedia Kb | Arts & recreation | 1992 |
| Ky Custodia Kb | Professional & scientific | 1991 |
| Ky Eiranrannan Argonautit | Financial services | 2005 |
| Ky Laippatie 7 Kb | Wholesale & retail | 1987 |
| Ky Magnum Data Kb | Information & communication | 2003 |
| Ky Mats Granbacka Kb | | 1987 |
| Ky Nautique Kb | Wholesale & retail | 1977 |
| Ky SP Solution | Transport & logistics | 1983 |
| Ky Seija Kangaste | Financial services | 1959 |
| Ky Suomen Posliini Kb | Manufacturing | 1982 |
| Ky Tex-Forum | | 1979 |
| Ky We Salute You | Construction | 2012 |
| Ky Åltrans Kb | Transport & logistics | 2006 |
| Kyberias Oy | Information & communication | 1997 |
| Kyberleijona Oy | Information & communication | 2011 |
| Kyl Salee Oy | Professional & scientific | 2021 |
| KylFix Oy | Construction | 2007 |
| Kylama Medica Oy | Health & social care | 2019 |
| Kylin Technology Oy | Information & communication | 2020 |
| Kyllikki Jones Oy | Financial services | 2015 |
| Kyllä Kannatti Oy | Hospitality | 2022 |
| Kylmähuolto BEL Oy | Other services | 2022 |
| Kylmäkonepalvelu OptiCool Oy | Construction | 1999 |
| Kylmämaster Oy | Construction | 2014 |
| Kylmäsepät Oy | Manufacturing | 1981 |
| Kylmäteräs Oy | Manufacturing | 2021 |
| Kylmäviisikko Oy | Construction | 1988 |
| Kylmääkuumaa Oy Kalltåvarmt Ab | Construction | 2022 |
| Kylpykruunu Oy | Construction | 2026 |
| Kylän Ihmiset Oy | Hospitality | 2018 |
| Kylän ompelimo Oy | Manufacturing | 2026 |
| Kymen Hammashuolto Oy | Health & social care | 2003 |
| Kymen Lehmuskoti Oy | Health & social care | 1993 |
| Kymen Leikkaus- ja Anestesiapalvelu Oy | Health & social care | 1991 |
| Kymen Moottoritalo Oy | Real estate | 1973 |
| Kymen Sointu Ky | | 1987 |
| Kymenlaakson Laatupäivystys Oy | Health & social care | 2020 |
| Kymenlaakson Sanelupalvelu Oy | Administrative & support | 2020 |
| Kymi BESS Oy | Energy | 2022 |
| Kymin Voima Oy | Energy | 1989 |
| Kymintien Kiinteistökorjaus Oy | Construction | 1994 |
| Kymmenen Hunttia Oy | Professional & scientific | 2019 |
| Kymppiterassit Oy | Construction | 2020 |
| Kymppivoima Oy | Energy | 1993 |
| Kynnet Finland Oy | Other services | 2022 |
| Kynnös Oy | Professional & scientific | 2021 |
| Kynäexpert Oy | Wholesale & retail | 1987 |
| Kynämikko Oy | Information & communication | 2023 |
| Kype Oy | Real estate | 1990 |
| Kypäristö Oy | Real estate | 1969 |
| Kyreno Oy | Professional & scientific | 2006 |
| Kyrkkölä Oy | Real estate | 2011 |
| Kyrknäs Kapital Oy Ab | Information & communication | 1990 |
| Kyrön LVI-Tekniikka Oy | Construction | 2019 |
| Kyröntaka Oy | Information & communication | 2011 |
| Kytera Oy | Information & communication | 2008 |
| Kytkemö Oy | Professional & scientific | 1990 |
| Kytkentäpalvelu Oy | Construction | 1976 |
| Kytobit Oy | Information & communication | 2012 |
| Kytänniemi Holding Oy | Financial services | 2021 |
| Kytö Capital Oy | Financial services | 2025 |
| Kytölän TP Oy | Financial services | 2015 |
| Kytölän Tuulipuisto Ky | Construction | 2015 |
| Kyydin Oy | Other services | 2021 |
| Kyymet Ky | | 1985 |
| Kyyti Mestarit Oy | Administrative & support | 2025 |
| Kyyzi Oy | Construction | 2002 |
| Kyöstilän Kello Oy | Wholesale & retail | 2021 |
| KÜLT Oy | Arts & recreation | 2023 |
| Kädenjälki käsityöt Oy | Wholesale & retail | 2025 |
| Kädet Käy Oy | Hospitality | 2025 |
| Käki-Mäkelä Holding Oy | Financial services | 2025 |
| Käkirohdos Oy | Wholesale & retail | 2025 |
| Käläkälä Media Oy | Arts & recreation | 2017 |
| Kämp Galleria Oy | Professional & scientific | 1998 |
| Kämp Oy | Hospitality | 1996 |
| Kämppä Gear Oy | Administrative & support | 2026 |
| Kämppäkaverit Oy | Real estate | 2007 |
| Käpylän Burger Oy | Hospitality | 2002 |
| Käpylän Eläinlääkäriasema Vetek Oy-Kottby Veterinärstation Vetek Ab | Professional & scientific | 1989 |
| Käpylän Juniorihalli Oy | Arts & recreation | 2006 |
| Käpylän Kylätalo Oy - Byhuset i Kottby Ab | Real estate | 2025 |
| Käpylän Merkki Oy | Wholesale & retail | 1990 |
| Käpylän Monipalvelut Oy | Professional & scientific | 2021 |
| Käpylän Sylvi Oy | Hospitality | 2024 |
| Käpylän Terveyspiste Oy | Real estate | 1984 |
| Käpylän hautaustoimisto Oy | Other services | 2024 |
| KäpylänFirma Oy | Transport & logistics | 2026 |
| Käpysäkki Oy | Financial services | 2014 |
| Kärki 10 taksi Oy | Transport & logistics | 2023 |
| Kärki Asianajotoimisto Oy | Professional & scientific | 2025 |
| Kärkikiinnike Oy | Wholesale & retail | 2009 |
| Kärkimedia Oy | Professional & scientific | 1995 |