| Jigsaw Construction Surrey Ltd | Construction | 2021 |
| Jinga Property Management and Maintenance Limited | Real estate | 2013 |
| John Hughes Fencing and Landscapes Ltd | Administrative & support | 2020 |
| Jonangel Limited | Health & social care | 2016 |
| Jordan Taylor Group Ltd | Wholesale & retail | 2024 |
| Jpac Electrical Limited | Construction | 2022 |
| JPC Consultants Limited | Professional & scientific | 2016 |
| JPM Surveying Services Limited | Professional & scientific | 2018 |
| JPS Demolition Limited | Construction | 2012 |
| JR Studio Ltd | Professional & scientific | 2014 |
| JSA UK Holdings Ltd | Wholesale & retail | 2021 |
| JT Auto Care Ltd | Wholesale & retail | 2026 |
| JT Risk Assessment Services Ltd | Extraterritorial | 2022 |
| JTI Motorsport Ltd | Wholesale & retail | 2021 |
| JTM Computer Installations Limited | Information & communication | 1998 |
| Jude's at the Shed Ltd | Hospitality | 2024 |
| June Bear Limited | Professional & scientific | 2019 |
| Just Bantams & Equestrian Ltd | Agriculture & fishing | 2025 |
| Just Bitz Ltd | Wholesale & retail | 2020 |
| Justin Theodore Limited | Professional & scientific | 2019 |
| K Construction & Design Ltd | Construction | 2021 |
| K Harris (Hampshire) Limited | Construction | 2011 |
| K Hawkes Training Limited | Education | 2024 |
| K Nash - Delegate Management Services Ltd | Administrative & support | 2023 |
| K.S.C. Holdings Limited | Real estate | 1982 |
| Kata Professional Services Limited | Professional & scientific | 2024 |
| KBC Properties Holdings Ltd | Real estate | 2026 |
| KBW QS Ltd | Professional & scientific | 2017 |
| KDR Aero Ltd | Manufacturing | 2009 |
| KDT Properties Ltd | Real estate | 2023 |
| Keep Attacking Apparel Limited | Wholesale & retail | 2020 |
| Keet Properties Ltd | Real estate | 2021 |
| Keith Henderson Accounting Limited | Professional & scientific | 2014 |
| Keith Payne Products Limited | Manufacturing | 1978 |
| Ken's Food Corner Limited | Hospitality | 2025 |
| Kerames Limited | Hospitality | 2007 |
| Kermodei Outdoors Ltd | Administrative & support | 2011 |
| Kestrel Loft & Roof Protection Ltd | Construction | 2023 |
| KEW Networks Ltd | Information & communication | 2011 |
| Keyford-Hallett Plumbing & Heating Ltd | Construction | 2023 |
| Kicki Carlsson Ltd | Wholesale & retail | 2013 |
| Kinetic Sports Massage and Remedial Therapy Ltd | Extraterritorial | 2020 |
| Kingfisher Surveying and Design Ltd | Professional & scientific | 2025 |
| Kingsley Organisation Enterprises Community Interest Company | Wholesale & retail | 2011 |
| Kingsley Organisation Limited | Health & social care | 1987 |
| Kingsley-Drake Estates Limited | Financial services | 2013 |
| Kitcombe Consulting Ltd | Professional & scientific | 2019 |
| Kith Limited | Financial services | 2018 |
| KJ COX Solicitor Limited | Professional & scientific | 2021 |
| Klaudia Cloud Ltd | Other services | 2019 |
| Klrp Spray Foam Removal Ltd | Construction | 2025 |
| Kold Star Air Conditioning and Refrigeration Ltd | Manufacturing | 2025 |
| Kompela Limited | Professional & scientific | 2024 |
| Konect Financial Ltd | Financial services | 2024 |
| Konect Holdings Ltd | Financial services | 2023 |
| Krew.Ldn Ltd | Wholesale & retail | 2025 |
| Kriel MP Ltd | Professional & scientific | 2022 |
| KSC Motor Company Ltd | Wholesale & retail | 2021 |
| Kudos Labs Ltd | Information & communication | 2013 |
| Kwami Ventures Ltd | Financial services | 2025 |
| L B Design Recruitment Ltd | Administrative & support | 2019 |
| L.R.G. Roofing Services Ltd | Construction | 2024 |
| L14M Ltd | Manufacturing | 2026 |
| LAB C Advisory Limited | Professional & scientific | 2025 |
| Lallyworks Ltd | Information & communication | 2025 |
| Landfall Property Limited | Construction | 1960 |
| Landspeed Affordable Homes Cowes Ltd | Construction | 2010 |
| Langbourn Limited | Financial services | 2015 |
| Laundry Developments Limited | Administrative & support | 2016 |
| LBP Dental Staffing Agency Ltd | Administrative & support | 2017 |
| LCJ Construction Ltd | Construction | 2021 |
| Leaton Research Ltd | Professional & scientific | 2022 |
| Legacy Project Limited | Health & social care | 2010 |
| Leisure Ideas LLP | | 2009 |
| Let’S Pass 1ST Ltd | Education | 2026 |
| Level UP DS Ltd | Education | 2026 |
| Lewis Close Whitehill Management Limited | Professional & scientific | 2017 |
| LGM Events Ltd | Arts & recreation | 2025 |
| Life Originals Limited | Wholesale & retail | 2025 |
| Lifestyle Financial Planning Limited | Financial services | 2003 |
| Lightini International Ltd | Wholesale & retail | 1996 |
| Lily Soutter Nutrition Ltd | Health & social care | 2023 |
| Lilyco Limited | Construction | 2020 |
| Limeflower PR Limited | Professional & scientific | 2016 |
| Limitless Creations LAB Ltd | Information & communication | 2024 |
| Limone (London) Limited | Other services | 2017 |
| Lina Farma Ltd | Wholesale & retail | 2024 |
| Lindford Business Park Ltd | Real estate | 2014 |
| Linguaservices Limited | Professional & scientific | 2013 |
| Lion Leasing Limited | Professional & scientific | 2025 |
| Liphook Cars Ltd | Transport & logistics | 2016 |
| Little Donkin Limited | Manufacturing | 2013 |
| Little Dreamers Day Nursery Ltd | Health & social care | 2023 |
| Little Treasures Childcare and Learning Centres Limited | Education | 2015 |
| Littleleaf Organics Limited | Wholesale & retail | 2017 |
| LMC of Farnham Ltd. | Wholesale & retail | 1982 |
| LNJ Management Ltd | Hospitality | 2024 |
| LNJ Property Ltd | Real estate | 2022 |
| Loaded Burger Ltd | Hospitality | 2021 |
| London Event Hire Limited | Hospitality | 2015 |