| Longdown Consultancy Limited | Professional & scientific | 2025 |
| Longmoor Barns Management Limited | Households | 1996 |
| Longmoor Farm Enterprises Limited | Wholesale & retail | 1988 |
| Longs Estates Ltd | Real estate | 2021 |
| Look OUT Below Ltd | Information & communication | 2021 |
| Loopy Bird Designs Limited | Wholesale & retail | 2022 |
| Lorekss Limited | Transport & logistics | 2016 |
| Lottie Loves Laser Ltd | Other services | 2024 |
| Lottie's Residential Properties Ltd | Real estate | 2024 |
| Lotus Care (Bucks) Limited | Real estate | 2019 |
| Lotus Florist Limited | Information & communication | 2025 |
| Louben Holdings Ltd | Real estate | 2021 |
| Louben Investments Ltd | Professional & scientific | 2025 |
| Loudh Ltd | Manufacturing | 2023 |
| Louisekay Ltd | Public administration | 2023 |
| Loule Solutions Ltd | Health & social care | 2016 |
| Love and Care(Uk) Ltd | Health & social care | 2019 |
| Love Ears Limited | Health & social care | 2021 |
| Love Lane Property Ltd | Real estate | 2019 |
| Love of Paws Ltd | Agriculture & fishing | 2025 |
| Loveesarees Ltd | Wholesale & retail | 2024 |
| Lovely BIT of Crumpet Ltd | Manufacturing | 2023 |
| Lovely Homes Stays Ltd | Real estate | 2023 |
| LOW Farm Liveries Limited | Agriculture & fishing | 2016 |
| LOW Meadow (Weston Turville) Management Company Limited | Administrative & support | 2018 |
| Lower Farm Cottages Management Limited | Real estate | 2005 |
| LP Luxury Detailing Ltd | Other services | 2024 |
| Lpeb Limited | Arts & recreation | 2014 |
| LPH Insight Ltd | Professional & scientific | 2022 |
| LR Scenery Ltd | Arts & recreation | 2020 |
| LRM Project Services Ltd | Construction | 2025 |
| LS Building & Renovation Ltd | Construction | 2025 |
| LSR Drain Services Ltd | Water & waste | 2023 |
| LT Motoring Ltd | Wholesale & retail | 2023 |
| LTC Transport Services Ltd | Transport & logistics | 2009 |
| Luan Electrical Ltd | Construction | 2023 |
| Lucan Pharma Ltd | Manufacturing | 2022 |
| Lucas&Matti Construction Ltd | Construction | 2026 |
| Luckytone Limited | Administrative & support | 2019 |
| Lucy’S Little Learners Ltd | Education | 2024 |
| Luff Landscaping Ltd | Administrative & support | 2024 |
| Luke Tubb Properties Ltd | Real estate | 2023 |
| Lumier Solutions Ltd | Professional & scientific | 2026 |
| Luminor Marketing Limited | Professional & scientific | 2022 |
| Luminor Training Limited | Professional & scientific | 2022 |
| Luminosity Lighting Services Ltd | Administrative & support | 2015 |
| Luminosity Software Limited | Information & communication | 2018 |
| Luminous Flux Games Ltd | Information & communication | 2026 |
| Luminwood Ltd | Administrative & support | 2018 |
| Lumière Ébène Ltd | Manufacturing | 2025 |
| Luna Talent Limited | Administrative & support | 2014 |
| Lunar Neuroimaging LLP | | 2017 |
| Luncaauto’S Ltd | Wholesale & retail | 2025 |
| Lund Halsey (Console Systems) Limited | Manufacturing | 1990 |
| Lunderson Ltd | Health & social care | 2025 |
| Lusty Furniture Company Limited | Wholesale & retail | 2008 |
| Lutchi Ltd | Administrative & support | 2017 |
| LUX Motion Limited | Administrative & support | 2021 |
| LUX PM Ltd | Professional & scientific | 2024 |
| Luxe CBD Limited | Wholesale & retail | 2019 |
| Luxebatex Limited | Wholesale & retail | 2024 |
| Luxedge Estates Limited | Real estate | 2025 |
| Luxeline Travel Ltd | Transport & logistics | 2024 |
| Luxscape Properties Ltd | Hospitality | 2024 |
| Luxury Fades Ltd | Other services | 2025 |
| Luxury Laundry Ltd | Other services | 2025 |
| Luxury Walls by MM Ltd | Construction | 2026 |
| Luxx Care Ltd | Health & social care | 2023 |
| LVP Motors Ltd | Wholesale & retail | 2023 |
| LWR Management Limited | Information & communication | 2023 |
| Lymphoma Action | Other services | 1998 |
| Lynx Gymnastics Club Limited | Arts & recreation | 1991 |
| Lysander and Sons Ltd | Construction | 2024 |
| M & K Cleaning Services (London) Limited | Administrative & support | 2011 |
| M & K Horrocks Associates Ltd | Administrative & support | 2006 |
| M & S Electrical Limited | Construction | 1997 |
| M & T Trade Windows & Doors Ltd | Manufacturing | 2009 |
| M & W Newco Limited | Professional & scientific | 2014 |
| M & W Property Services Limited | Administrative & support | 2006 |
| M a Simmonds Property Limited | Real estate | 2025 |
| M and C Pension Limited | Extraterritorial | 2015 |
| M and E Site Solutions Limited | Construction | 2023 |
| M and S Valeting Services Ltd | Administrative & support | 2025 |
| M C Bromell Ltd | Professional & scientific | 2019 |
| M D Auto Care Ltd. | Wholesale & retail | 2015 |
| M H Fuel Installation & Maintenance Limited | Construction | 2009 |
| M Haigh Consulting Limited | Professional & scientific | 2003 |
| M I S Electrical UK Limited | Other services | 2009 |
| M J E Mechanical Engineering Limited | Manufacturing | 2006 |
| M J Electrical Engineering Limited | Construction | 2010 |
| M Katerina V Limited | Transport & logistics | 2019 |
| M Kosla Ltd | Transport & logistics | 2019 |
| M L I (Properties) Ltd | Real estate | 1935 |
| M O Barrett Limited | Information & communication | 2016 |
| M P Jordan Surveys Ltd | Professional & scientific | 2023 |
| M Parker Instrumentation Specialist Limited | Administrative & support | 2013 |
| M Paul Glazing Limited | Construction | 2014 |
| M Powell Landscaping Services Ltd | Administrative & support | 2021 |
| M S Accountancy Ltd | Professional & scientific | 2017 |
| M Shabeer TM Ltd | Construction | 2024 |