| K&S Aerospace Components Limited | Manufacturing | 2010 |
| K&S Scrapmetals Ltd | Water & waste | 2013 |
| K-Tech Enterprise Ltd | Information & communication | 2021 |
| K-Vibe Limited | Wholesale & retail | 2025 |
| K. D. R. Properties Ltd | Real estate | 2020 |
| K. N. Care Limited | Health & social care | 2017 |
| K. Wilson Limited | Wholesale & retail | 1985 |
| K.A. Russell Limited | Other services | 2024 |
| K.A.B. One Ltd | Construction | 2013 |
| K.B. Salon Supplies Limited | Wholesale & retail | 2004 |
| K.E.R Civil Groundworks Ltd | Water & waste | 2020 |
| K.E.S. (U.K.) Limited | Wholesale & retail | 1985 |
| K.G. Madge and SON Limited | Real estate | 1962 |
| K.H Trimz Barber Shop Ltd | Other services | 2023 |
| K.K.T.K. Limited | Hospitality | 1999 |
| K.P.A. Electrical Services Ltd | Construction | 2023 |
| K.P.S. Prestige Group Ltd | Wholesale & retail | 2020 |
| K.S.Z Building and Decorating Ltd | Construction | 2018 |
| K1 Best Barber Limited | Other services | 2025 |
| K1 MOT Ltd | Wholesale & retail | 2023 |
| K1 Tyre & Servicing Ltd | Wholesale & retail | 2020 |
| K2 Building Services Ltd | Other services | 2023 |
| K2 Swift Removals Ltd | Transport & logistics | 2026 |
| K2HOARD Ltd | Wholesale & retail | 2024 |
| K4 + Ltd. | Arts & recreation | 1989 |
| K4 Global Group Limited | Financial services | 2025 |
| K9BEHAVIOUR Ltd | Other services | 2025 |
| KA Trading Limited | Wholesale & retail | 2008 |
| Kaab Limited | Wholesale & retail | 2024 |
| Kaamco Transport Ltd | Transport & logistics | 2024 |
| Kacprzak Properties Ltd | Real estate | 2021 |
| KAD Scaffolding Ltd | Construction | 2020 |
| Kada IT Consultants Limited | Information & communication | 2018 |
| Kadampa Meditation Centre (KMC) Southampton Ltd. | Education | 1995 |
| Kadena Digital Limited | Information & communication | 2025 |
| Kaellies Limited | Financial services | 2005 |
| Kaezn Limited | Information & communication | 2024 |
| KAG International Music Ltd | Information & communication | 2025 |
| KAI Sports Ltd. | Wholesale & retail | 1998 |
| Kai&Nt Ltd | Wholesale & retail | 2025 |
| Kaiizen Coaching Limited | Professional & scientific | 2024 |
| Kaila and K Limited | Wholesale & retail | 2015 |
| Kairaj DP Limited | Wholesale & retail | 2025 |
| Kaisuva Limited | Transport & logistics | 2025 |
| Kaithree Photonics Limited | Manufacturing | 2017 |
| Kaizen Creative Group Ltd | Information & communication | 2024 |
| Kaizen Cuisine Ltd | Hospitality | 2019 |
| Kaizen Holdings Ltd | Financial services | 2025 |
| Kaizen LGV Ltd | Transport & logistics | 2013 |
| Kaizen Medical Ltd | Health & social care | 2017 |
| Kaizen Performance Ltd | Arts & recreation | 2019 |
| Kajavida Limited | Manufacturing | 2007 |
| Kajgop Ltd | Health & social care | 2011 |
| Kajol Limited | Real estate | 2018 |
| Kakar Holdings Limited | Financial services | 2021 |
| Kaki Limited | Health & social care | 2024 |
| Kalday Ltd | Construction | 2022 |
| Kali Mirchi (UK) Limited | Hospitality | 2013 |
| Kalsoom Ltd | Real estate | 2022 |
| KALY26 Ltd | Real estate | 2026 |
| KAM Quality Scaffolding Ltd | Construction | 2017 |
| KAM Transport Ltd | Transport & logistics | 2025 |
| Kamalansh Limited | Information & communication | 2026 |
| Kamalia Properties Limited | Real estate | 2019 |
| Kami Traders Ltd | Wholesale & retail | 2025 |
| Kamikore Ltd | Health & social care | 2018 |
| Kancelaria Podatkowa Moro Ltd | Professional & scientific | 2021 |
| Kandy Cleaning Ltd | Administrative & support | 2023 |
| Kandy Software Services Limited | Information & communication | 2014 |
| Kang & Ladher Property Development Limited | Real estate | 2001 |
| Kaniscko Limited | Professional & scientific | 1989 |
| Kansara Logistics Ltd | Transport & logistics | 2025 |
| Kanukollu Ltd | Health & social care | 2022 |
| Kanyal Properties Ltd | Real estate | 2025 |
| Kanzi Limited | Information & communication | 2007 |
| Kao.K Food Ltd | Hospitality | 2023 |
| Kaoz Printworks Limited | Arts & recreation | 2002 |
| Kapusta IO Limited | Information & communication | 2017 |
| Kara Accountants (Romsey) Limited | Professional & scientific | 2014 |
| Kara Accountants Limited | Professional & scientific | 2005 |
| Karaden Limited | Construction | 1987 |
| Karak Chai South Limited | Hospitality | 2022 |
| Karam Cars Ltd | Wholesale & retail | 2026 |
| Karam Transport Limited | Transport & logistics | 2025 |
| Karcol Limited | Hospitality | 2018 |
| Kards and Keepsakes Gifts and Chocolates Ltd | Wholesale & retail | 2024 |
| Kards and Keepsakes LLP | | 2019 |
| Kare Financial Management Consultants Ltd | Professional & scientific | 2012 |
| Kareem Properties Limited | Real estate | 2020 |
| Karens London Limited | Hospitality | 2023 |
| Karibu Care Limited | Health & social care | 2013 |
| Karim Trade Ltd | Construction | 2019 |
| Karing Limited | Health & social care | 2023 |
| Karma TM Ltd | Construction | 2022 |
| Karmac Global Limited | Administrative & support | 2023 |
| Karol Marcin Wyrwas Ltd | Transport & logistics | 2024 |
| Karol Sobuta Ltd | Construction | 2017 |
| Karpinski Logistics Ltd | Transport & logistics | 2025 |
| Karstation Ltd | Information & communication | 2024 |
| Karter Kapital Estates Limited | Real estate | 2023 |