| Kene Property Holdings Limited | Real estate | 2025 |
| Kene Property Maintenance Limited | Construction | 2025 |
| Kenwell Properties Limited | Financial services | 1997 |
| KEO Water Services Ltd | Water & waste | 2025 |
| Kerry Knight Ltd | Professional & scientific | 2019 |
| Key Facilities Group Limited | Administrative & support | 2011 |
| Key Facilities UK Group Ltd | Other services | 2026 |
| Key Holders Group Ltd | Transport & logistics | 2024 |
| Key Holders UK Ltd | Other services | 2025 |
| KH Brightlingsea Limited | Hospitality | 2019 |
| King Georges View Limited | Households | 2007 |
| Kingswood Court (Braintree) Management Company Limited | Real estate | 2013 |
| KJJ Smith Plumbing and Heating Ltd | Construction | 2022 |
| Klass Group Ltd | Administrative & support | 2020 |
| KLT Homes Limited | Real estate | 2022 |
| Knossington and Somerby Pre-School | Education | 2006 |
| Knox Systems Ltd | Information & communication | 2025 |
| Kodr Digital Ltd | Information & communication | 2008 |
| Kolne Kooling Limited | Construction | 2023 |
| KP Storage Limited | Transport & logistics | 2017 |
| KR Window Cleaning Holdings Limited | Households | 2025 |
| KR Window Cleaning Limited | Administrative & support | 2024 |
| Kreis Medical Limited | Health & social care | 2018 |
| KRP Fire Protection Services Limited | Administrative & support | 2007 |
| KRP Services Limited | Extraterritorial | 2020 |
| KTB Investments Group Ltd | Financial services | 2025 |
| Kudos Car Sales Ltd | Wholesale & retail | 2019 |
| Kulak Catering Limited | Administrative & support | 2016 |
| KÔR Pilates Ltd | Arts & recreation | 2026 |
| L a Style Limited | Real estate | 2010 |
| Lady & the Tramper Limited | Wholesale & retail | 2018 |
| Lafemmeverte Limited | Health & social care | 2018 |
| Lakeview Homes Ltd | Real estate | 2024 |
| Lalas Beauty Boutique Ltd | Other services | 2025 |
| LAP Morex Ltd | Professional & scientific | 2014 |
| Lasertech IT Services Limited | Other services | 2005 |
| Lashedbyaim Ltd | Other services | 2024 |
| Latitude 29 Ltd | Information & communication | 2005 |
| Lawprep Academy Ltd | Education | 2026 |
| Lawrence Interiors Limited | Construction | 2015 |
| Lblt Transport Ltd. | Transport & logistics | 2016 |
| LEA Bridge Lofts Ltd | Households | 2023 |
| Leadbeater Solutions Limited | Administrative & support | 2017 |
| Leadership Through Data Ltd | Professional & scientific | 2017 |
| Leading Edge Aviation Graphics Limited | Extraterritorial | 2011 |
| Leading Edge Fire Doors Ltd | Construction | 2025 |
| Leading Edge Graphics Limited | Manufacturing | 2010 |
| Learnto CIC | Education | 2024 |
| LEE Purdy Ltd | Construction | 2017 |
| Leestock Music Festival Limited | Arts & recreation | 2012 |
| Legacy Hill LLP | | 2021 |
| Lemon INK Ltd | Information & communication | 2014 |
| Lenden & Swone Ltd | Information & communication | 2025 |
| Lercot Limited | Wholesale & retail | 2000 |
| Letmix Ltd | Real estate | 2026 |
| Lets Light Ltd | Professional & scientific | 2023 |
| Level Headed Productions Limited | Manufacturing | 2005 |
| Level Line Home Improvements Ltd | Construction | 2025 |
| Lewis Financial Trading Ltd | Financial services | 2005 |
| Lexden Builders Limited | Construction | 2009 |
| Lexden Developments Limited | Real estate | 2018 |
| Lexden Technologies Ltd | Information & communication | 2007 |
| Leyson Services Ltd | Construction | 2025 |
| LGP Europe, Ltd | Wholesale & retail | 2016 |
| LHB Trade Limited | Construction | 2012 |
| LHC Mine Finance Ltd | Financial services | 2016 |
| Lifestyle Design Ltd | Construction | 2004 |
| Lilac Court (Cambridge) Limited | Households | 1990 |
| Limes Country Club Limited the | Real estate | 1969 |
| Limited Edition Gallery and Framing Ltd | Wholesale & retail | 2018 |
| Linkswood Equine Vets Limited | Professional & scientific | 2022 |
| Lionshead Capital Ltd | Professional & scientific | 2015 |
| LIT Within Limited | Arts & recreation | 2014 |
| Little Bradfords House Management (Braintree) Limited | Households | 1973 |
| Little Crown J Ltd | Health & social care | 2017 |
| Little Footprints Limited | Health & social care | 2006 |
| Little ME Preschool Ltd | Education | 2015 |
| Little Urchins (Franchising) Limited | Professional & scientific | 1999 |
| Livsthorpe Ltd | Health & social care | 2023 |
| Lizard Consultancy Ltd | Professional & scientific | 2015 |
| Lo-Ev Limited | Manufacturing | 2022 |
| Loam Photography Studios Ltd | Professional & scientific | 2024 |
| Loanne Limited | Administrative & support | 2012 |
| Lock Agricultural Limited | Manufacturing | 2018 |
| Logic Consulting Ltd | Information & communication | 2022 |
| Logoswave Ltd | Financial services | 2025 |
| London & Home Counties Preservation Incorporating a Dobing Ltd | Construction | 2003 |
| London LOW Voltage Ltd | Construction | 2022 |
| London Road (Phase 2) Management Company Limited | Households | 1993 |
| Longwell Retail Services Limited | Wholesale & retail | 1998 |
| Lothiredon Ltd | Information & communication | 2020 |
| Lotus Travels and Retreats Ltd | Administrative & support | 2017 |
| Love 4 Homes Limited | Construction | 2022 |
| Love Toast Franchising Limited | Administrative & support | 2026 |
| Love Toast Holdings Ltd | Financial services | 2026 |
| LR Property Limited | Real estate | 2024 |
| LR Specialist Engineering Ltd | Professional & scientific | 2012 |
| LT Listings Ltd | Information & communication | 2025 |
| Luma House Productions Limited | Information & communication | 2026 |
| Luwi Limited | Real estate | 2024 |