| Local Tree Services & Landscaping Ltd | Administrative & support | 2025 |
| Lock N Roll Locksmith (Beds) Ltd | Other services | 2025 |
| Lodestar Advisory Limited | Professional & scientific | 2026 |
| Loftkit Limited | Wholesale & retail | 2026 |
| Logans Psychological Services Ltd | Education | 2023 |
| Logica Engineering Limited | Professional & scientific | 1987 |
| Logitronic Ltd | Information & communication | 2026 |
| LOL Properties Ltd | Real estate | 2023 |
| London & Herts Sparks Ltd | Information & communication | 2019 |
| London Associates Design Limited | Professional & scientific | 2011 |
| London Data Services Ltd | Information & communication | 2022 |
| London Electrical Training Centre Ltd | Extraterritorial | 2022 |
| London EYE Production Limited | Information & communication | 2020 |
| London GAS Training Centre Ltd | Education | 2020 |
| London Look Accessories Ltd | Wholesale & retail | 2023 |
| London Market Training Limited | Professional & scientific | 2012 |
| London Road (Buckingham) Management Company Limited | Households | 2012 |
| London Thermal Imaging Ltd | Construction | 2024 |
| Londons Finest Tree Surgeons Ltd | Administrative & support | 2026 |
| Longbow Scenic Limited | Construction | 2024 |
| Longevity Actuary Limited | Financial services | 2020 |
| Longhorn Gardens (Aston Clinton) Management Company Limited | Households | 2017 |
| Longshot Consulting Ltd | Professional & scientific | 2025 |
| Longwood Avenue (RTM) Company Limited | Households | 2010 |
| Lordcorp Ltd | Information & communication | 2020 |
| Lorna Lowe Limited | Manufacturing | 2004 |
| Lost Moment Enterprises (UK) Limited | Information & communication | 1985 |
| Lost on Mars Limited | Arts & recreation | 2022 |
| LOU Shearn Creative Services Ltd | Administrative & support | 2025 |
| Loughton Gate Limited | Real estate | 2013 |
| Louiec Limited | Information & communication | 2017 |
| Louise Peacock Limited | Professional & scientific | 2022 |
| Loulou Scenes Ltd | Information & communication | 2021 |
| Louloutes & Co Ltd | Information & communication | 2013 |
| Love Flowers (Rickmansworth) Limited | Wholesale & retail | 2016 |
| Love Your Group Ltd | Administrative & support | 2017 |
| Loved Before Ltd | Wholesale & retail | 2019 |
| Lovina Healthcare Ltd | Health & social care | 2025 |
| LP Electrical Services Ltd | Construction | 2026 |
| LPK Group Limited | Financial services | 2023 |
| LR Capital Limited | Financial services | 2023 |
| LS Equisports Therapy Ltd | Professional & scientific | 2025 |
| LS Productions Services Ltd | Construction | 2022 |
| Lsdeanmedical Ltd | Health & social care | 2023 |
| Lucas Decor London Ltd | Construction | 2017 |
| Lucid Research Services Ltd | Professional & scientific | 2023 |
| Lucky Happy Ltd | Transport & logistics | 2015 |
| Lucky Thai Chef Limited | Hospitality | 2023 |
| Lucy Hart Bridal Ltd | Wholesale & retail | 2016 |
| Lucy Houle England Ltd | Manufacturing | 2019 |
| Luja Paint Services Limited | Construction | 2014 |
| LUK Immo Ltd | Financial services | 2021 |
| Luke Cave Hairdressing Limited | Other services | 2011 |
| Lumetrix Ltd | Information & communication | 2024 |
| Lumina Consultancy Limited | Health & social care | 2025 |
| Luna Construction (Herts) Ltd | Construction | 2023 |
| Luna Solutions Ltd | Professional & scientific | 2022 |
| Luna's Wellness Limited | Other services | 2025 |
| Lunar Records Ltd | Information & communication | 2014 |
| Lunasphere Limited | Information & communication | 2026 |
| Lury Consulting Limited | Professional & scientific | 2021 |
| Luton Park View Management Limited | Households | 2003 |
| Lutona Limited | Health & social care | 2024 |
| Lutts Group Limited | Transport & logistics | 2022 |
| Lutts Pallets Limited | Transport & logistics | 2022 |
| Lutts Transport Services Limited | Real estate | 1999 |
| LUX Monkey Limited | Information & communication | 2008 |
| LUX Plumbing & Heating Ltd | Construction | 2016 |
| Luxe 101 Limited | Professional & scientific | 2024 |
| Luxe Living Spaces Limited | Households | 2024 |
| Luxury Christmas Creations Ltd | Administrative & support | 2025 |
| LW Express Ltd | Transport & logistics | 2023 |
| Lycris Limited | Administrative & support | 2013 |
| Lynchpin Consultants Limited | Administrative & support | 2005 |
| Lynda Petal Consulting Limited | Information & communication | 2020 |
| Löger Ltd | Wholesale & retail | 2026 |
| M & L Leisure Limited | Administrative & support | 2021 |
| M Goddridge Financial Consultancy Ltd | Professional & scientific | 2016 |
| M L Gonzalez Ltd | Administrative & support | 2021 |
| M Sach Ltd | Health & social care | 2025 |
| M T Power Limited | Manufacturing | 2009 |
| M&M Properties (Lettings) Limited | Real estate | 2005 |
| M&M Properties (Sales) Limited | Real estate | 2005 |
| M&N Krisan Ltd | Transport & logistics | 2018 |
| M&R Scaffolding Access & Safety Ltd | Construction | 2024 |
| M.E. Mastic Ltd | Construction | 2018 |
| M.J & R Properties Limited | Real estate | 2025 |
| M.S.White(Dunstable)Limited | Construction | 1962 |
| M0MENTUM M3DIA Limited | Professional & scientific | 2024 |
| MA Leung Properties Ltd | Real estate | 2024 |
| Macaulay Carpentry Ltd | Construction | 2012 |
| Mach 1 Solutions Limited | Information & communication | 1994 |
| Machina Distribuo Ltd | Wholesale & retail | 2026 |
| Madaz Autos and Sons Limited | Wholesale & retail | 2018 |
| Madeleine Narciso Limited | Professional & scientific | 2017 |
| Magenta Orchard Limited | Households | 1995 |
| Magnet Media Ltd | Professional & scientific | 2025 |
| Maham Ammar Ltd | Manufacturing | 2021 |
| Maic Ltd | Professional & scientific | 2020 |
| Main Event Lighting Ltd | Information & communication | 2024 |