| Jjsc Limited | Wholesale & retail | 2012 |
| JJW Wisewhiz Ltd | Real estate | 2024 |
| JK Info Limited | Information & communication | 2018 |
| JM Fortune Ltd | Real estate | 2016 |
| JMN Strategy Limited | Professional & scientific | 2025 |
| JNB Enterprises Ltd | Real estate | 1999 |
| John Snelling Construction Ltd | Construction | 2011 |
| Jones Accounting Solutions Limited | Professional & scientific | 2006 |
| Joseph Rose Advisory Ltd | Professional & scientific | 2024 |
| JP Technologies Ltd | Information & communication | 2016 |
| JRC Partners Ltd | Administrative & support | 2010 |
| JS & MS Properties Ltd | Real estate | 2022 |
| JS Local Plumbing and Heating Ltd | Construction | 2026 |
| JSB & SON Limited | Construction | 2026 |
| JSK Solutions Ltd | Professional & scientific | 2023 |
| JSK UK Holdings Ltd | Financial services | 2024 |
| Jsptkp Holdings Ltd | Information & communication | 2025 |
| JSR Data Solutions Limited | Information & communication | 2021 |
| JST Kart Shop Ltd | Wholesale & retail | 2025 |
| Juice MAN Limited | Manufacturing | 2013 |
| Julia Consulting Limited | Professional & scientific | 2009 |
| Juliette O Designs Ltd | Extraterritorial | 2024 |
| Junelim Experience Design Ltd. | Information & communication | 2024 |
| Jush London Ltd | Manufacturing | 2021 |
| Just Stone Direct Limited | Administrative & support | 2008 |
| Just Tax & Accounts Consulting Limited | Professional & scientific | 2021 |
| Just ZEN Ltd | Health & social care | 2025 |
| Justice Mallow Limited | Information & communication | 1998 |
| Justransfer Ltd | Information & communication | 2023 |
| K & K Dental Care Ltd | Health & social care | 2020 |
| K & S Operations Limited | Hospitality | 2010 |
| K 4 Komfort Ltd | Real estate | 2024 |
| K.G. Patel & Sons Limited | Wholesale & retail | 1981 |
| K.Gosrani.Eye Limited | Health & social care | 2013 |
| K2 Management Consultancy Services Ltd | Professional & scientific | 2020 |
| Kabhi Enterprises Ltd | Construction | 2024 |
| Kampd Limited | Other services | 2016 |
| Kara Properties Group Limited | | 2023 |
| Kartwell Limited | Real estate | 2014 |
| KAS Real Estates Limited | Real estate | 2020 |
| Katepal Products UK Limited | Wholesale & retail | 2003 |
| Kathtineam(Holdings)Limited | Real estate | 1955 |
| Kaveltech Limited | Information & communication | 2020 |
| Kavnik Properties Ltd | Real estate | 2013 |
| Kavo Dental Limited | Health & social care | 1969 |
| KCA Roast Limited | Hospitality | 2014 |
| KCA Ventures Limited | Real estate | 2024 |
| KDE IT Services Limited | Information & communication | 2013 |
| Keddie Scott Associates Limited | Arts & recreation | 2005 |
| Keertana Information Technology Solutions Limited | Information & communication | 2003 |
| Keith Mills Limited | Wholesale & retail | 2003 |
| Kelly Wilkes Legal Services Ltd | Financial services | 2018 |
| Kenton Avenue Residents Association Limited | Households | 1993 |
| KEW Little Pigs Farm Ltd | Agriculture & fishing | 2016 |
| Key Opulent Limited | Households | 2025 |
| Khan Spice Ltd | Hospitality | 2026 |
| Kian Apex Ltd | Wholesale & retail | 2017 |
| KIM & Company Limited | Wholesale & retail | 1996 |
| Kincar Estates Limited | Real estate | 1939 |
| Kinetic Barn Ltd | Arts & recreation | 2025 |
| KINEX18 Ltd | Health & social care | 2026 |
| King's Church Amersham | Other services | 2010 |
| Kingfisher & Clarke Limited | Administrative & support | 2022 |
| Kingfisher Lure Limited | Hospitality | 2023 |
| Kingsgate Farm Ltd | Financial services | 2022 |
| Kingsmen Group Ltd | Transport & logistics | 2017 |
| Kippax Property Limited | Construction | 2016 |
| Kirkham Way Management Company Limited | Households | 2013 |
| Kiwi Investments Ltd | Real estate | 2024 |
| Kiwi Psychologist Limited | Health & social care | 2013 |
| KJS Coatings Ltd | Construction | 2021 |
| KJW Beech Farm Limited | Construction | 2023 |
| Kloudz.Io Ltd | Information & communication | 2019 |
| Kmine Info Solutions Ltd | Information & communication | 2016 |
| KMM Solutions Ltd | Information & communication | 2012 |
| KMR Global Ltd | Wholesale & retail | 2023 |
| Knights of the Round Cable Ltd | Construction | 2023 |
| Koan Advisory Ltd | Information & communication | 2020 |
| Koho Ltd | Hospitality | 2009 |
| Kokosanemi Amersham Limited | Hospitality | 2025 |
| Kokosanemi Group Limited | Administrative & support | 2025 |
| Korrosionkure Global Ltd | Wholesale & retail | 2026 |
| Kotchat Holding Ltd | Real estate | 2017 |
| KP Property Maintenance Ltd | Construction | 2018 |
| Krafty Clothing Ltd | Wholesale & retail | 2019 |
| Kris Zwaig Ltd | Professional & scientific | 2021 |
| Krishna Chaitanya Private Ltd | Information & communication | 2025 |
| Kroma Post Limited | Information & communication | 2015 |
| KRP Capital Limited | Real estate | 2018 |
| KRP Properties Ltd | Real estate | 2020 |
| Krpatel Limited | Health & social care | 2014 |
| Kudos Athletics Limited | Education | 2019 |
| KVD Technology Ltd | Information & communication | 2013 |
| KW Leather Design & Manufacturing Ltd | Manufacturing | 2019 |
| L&P Strategic Ltd | Real estate | 2019 |
| L2 Building Design Services Limited | Professional & scientific | 2016 |
| L2D Limited | Wholesale & retail | 2010 |
| Labmatch Limited | Real estate | 2025 |
| Labrador Laboratories Ltd | Wholesale & retail | 2023 |
| Ladonovan Ltd | Information & communication | 2012 |