| JRH Project Consultancy Limited | Wholesale & retail | 2016 |
| JRM Controls Ltd | Construction | 2018 |
| JRO Private Finance Ltd | Financial services | 2026 |
| JS Coach and Consult Ltd | Professional & scientific | 2026 |
| JS Electrical Testing Ltd | Construction | 2015 |
| JS Garden Reclaim Limited | Wholesale & retail | 2019 |
| JS Gordon Ltd | Construction | 2017 |
| JS Productions Limited | Information & communication | 2017 |
| Jsara-It Limited | Information & communication | 2023 |
| JSJ London Developments Limited | Construction | 2017 |
| Jsmb International Ltd | Wholesale & retail | 2021 |
| JSP Consultants Limited | Administrative & support | 2011 |
| JSS (GB) Ltd | Extraterritorial | 2004 |
| JST Holidays Limited | Hospitality | 2025 |
| JT Pedals Ltd | Manufacturing | 2020 |
| JTC Building Services Limited | Administrative & support | 2019 |
| JTD Consulting Ltd | Professional & scientific | 2025 |
| Jude Mobile Mechanical Services Ltd | Wholesale & retail | 2017 |
| Jufeba UK Ltd | Professional & scientific | 2025 |
| Juice Energy Consultants Ltd | Professional & scientific | 2016 |
| Jules MAY Ltd | Financial services | 2024 |
| Julian Eade Antiques Ltd | Wholesale & retail | 2021 |
| Julian Waters Ltd | Professional & scientific | 2022 |
| Juliana's Luxury Villas Limited | Hospitality | 2024 |
| Junction Court Management Limited | Real estate | 2011 |
| Juniper CFO Services Limited | Professional & scientific | 2019 |
| Juniper Place Management Company Limited | Households | 2012 |
| Just Electrical Services Limited | Construction | 2006 |
| Just Interims Limited | Administrative & support | 2010 |
| Justin Wynn Limited | Wholesale & retail | 2003 |
| Justjopubs Ltd | Hospitality | 2026 |
| JV Ice Hockey Academy Ltd | Arts & recreation | 2021 |
| JWT Plastering Ltd | Construction | 2025 |
| JXN Enterprise Ltd | Health & social care | 2025 |
| K & a Property Development Ltd | Real estate | 2024 |
| K & H Events LLP | | 2012 |
| K & K Gauld Ltd | Construction | 2013 |
| K & P Tyres (Ewell) Limited | Wholesale & retail | 1987 |
| K & R C Services Limited | Professional & scientific | 2002 |
| K Beauty Spa Ltd | Other services | 2022 |
| K Engineers Ltd | Construction | 2019 |
| K Hill Catering Ltd | Hospitality | 2017 |
| K&H Cuisine Ltd | Hospitality | 2021 |
| K&U Meat and Grocers Ltd | Wholesale & retail | 2024 |
| K.G. Associates Limited | Financial services | 1996 |
| K.J.Rahtinam Limited | Health & social care | 2021 |
| K.P. Interior Services Ltd | Construction | 2024 |
| K1 Restaurant Holding Ltd | Financial services | 2022 |
| Kabuni Metaverse Ltd | Information & communication | 2022 |
| Kabuni Ventures Limited | Information & communication | 2018 |
| Kado Audiovisual Limited | Professional & scientific | 2025 |
| KAI and Alfie's Stores Ltd | Wholesale & retail | 2025 |
| Kailash Food Ltd | Hospitality | 2025 |
| Kaizenstar Ltd | Real estate | 2015 |
| Kamal Coffee Ltd | Hospitality | 2023 |
| Kampung Pala Properties Limited | Real estate | 2019 |
| Kamteer Consulting Limited | Professional & scientific | 2017 |
| Kandg Biella Investments Ltd | Real estate | 2024 |
| Kandg Biella Ltd | Real estate | 2024 |
| Kandg Biella Ventures LLP | | 2024 |
| Kangayra Limited | Information & communication | 2016 |
| Kare 4 YOU Surrey Ltd | Administrative & support | 2021 |
| Karimor Limited | Transport & logistics | 2007 |
| Karma Sounds Ltd | Information & communication | 2021 |
| Karmic Ventures Limited | Information & communication | 2025 |
| Karoo Solutions Limited | Professional & scientific | 2014 |
| KAS Carpentry Ltd | Construction | 2026 |
| KAS Global Ventures Ltd | Administrative & support | 2025 |
| Kasem Property Limited | Real estate | 2023 |
| Kasem Travels Limited | Administrative & support | 2026 |
| Kasia Fortuna Limited | Other services | 2024 |
| Kass Elise-Jane Ltd | Health & social care | 2013 |
| Kat's Adventures Limited | Administrative & support | 2012 |
| Katana Security Design Solutions Limited | Information & communication | 2011 |
| Kate Hair & Makeup Ltd | Other services | 2024 |
| Katherine Bletcher Limited | Professional & scientific | 2023 |
| Katherine Grant Limited | Manufacturing | 2012 |
| Katie Limited | Financial services | 2011 |
| Kavbro Build Limited | Construction | 1997 |
| Kavbro Builders Limited | Construction | 2009 |
| Kaybridge Residential Ltd | Real estate | 2018 |
| Kaygenic Limited | Wholesale & retail | 2021 |
| Kayleigh Fawcett Consulting Limited | Professional & scientific | 2019 |
| KBR Group Holdings Ltd | Financial services | 2025 |
| KC Driveco Ltd | Arts & recreation | 2022 |
| KC Services Limited | Health & social care | 2016 |
| Kcom Online Limited | Administrative & support | 2015 |
| Kcrib Limited | Real estate | 2015 |
| Keel London Limited | Professional & scientific | 2010 |
| Keenwolf Marketing Services Ltd | Professional & scientific | 2024 |
| Keiko VLR Ltd | Arts & recreation | 2025 |
| KEL Project Management Limited | Construction | 2025 |
| Kelsey.Thelavenderspa Ltd | Other services | 2025 |
| Kelsham Trading Ltd | Wholesale & retail | 2021 |
| Kencort Limited | Other services | 2017 |
| Kenmore (Epsom) Management Company Limited | Households | 2016 |
| Kent and Surrey Bloodhounds LLP | | 2011 |
| Kepler Communications Group Limited | Professional & scientific | 2018 |
| Kersnovske Group Ltd | Wholesale & retail | 2026 |
| Kerwick & Rogers Dental Laboratory Limited | Health & social care | 2006 |