| Lipton Consulting Limited | Administrative & support | 1988 |
| Lisa Dawn Coaching Limited | Professional & scientific | 2021 |
| Little Balloon Box Limited | Wholesale & retail | 2022 |
| Little Nomads Ltd | Education | 2025 |
| Live to Paddle Ltd | Wholesale & retail | 2020 |
| LJB Construction Management Limited | Construction | 2025 |
| LK Makeup Ltd | Information & communication | 2025 |
| LM Barbers Ltd | Other services | 2025 |
| LNR Holdings Ltd | Professional & scientific | 2023 |
| Lockdown Scaffold Alarms Limited | Administrative & support | 2025 |
| Locksbury Services Limited | Construction | 2009 |
| Lodge Farm Fencing Ltd | Energy | 2011 |
| Loella Holdings Limited | Real estate | 2016 |
| Logik Property Limited | Real estate | 2018 |
| Logik Property Management Limited | Real estate | 2018 |
| LOK Saddlery & Leatherwork Limited | Other services | 2021 |
| London Capital Investments Limited | Real estate | 2025 |
| London Chemicals & Resources Limited | Wholesale & retail | 2005 |
| London Decking Company Limited | Other services | 2008 |
| London Direct Commercial Air Conditioning & Facilities Ltd | Energy | 2019 |
| London Investor Roadshows and Chauffeur Services Limited | Transport & logistics | 2013 |
| London Lawn Turf Co Ltd | Administrative & support | 2018 |
| London Roofing & Consultancy Ltd | Construction | 2017 |
| London United Rugby Club Limited | Administrative & support | 2009 |
| Londontaxipr Limited | Professional & scientific | 2015 |
| Lorien Consulting Limited | Professional & scientific | 2022 |
| Lotus Nails Biggin Hill Limited | Other services | 2024 |
| Louis Baron Designs Ltd. | Wholesale & retail | 1993 |
| LSS Construction Services Ltd | Construction | 2025 |
| Lucy Cain Design Ltd | Arts & recreation | 2025 |
| Lucy Miller Creative Ltd | Professional & scientific | 2021 |
| Lukreda Ltd | Other services | 2024 |
| Lumex Holding Limited | Financial services | 2026 |
| Lunarae Limited | Wholesale & retail | 2026 |
| Luper Landscaping & Building Maintenance Ltd | Construction | 2026 |
| LUX Valet Ltd | Administrative & support | 2018 |
| Luxury Lighting and Electrical Supplies Ltd | Wholesale & retail | 2012 |
| Lynn Crilly Limited | Health & social care | 2010 |
| Lynx Signs Limited | Manufacturing | 2002 |
| Lyrical Ltd | Administrative & support | 2020 |
| Löwenberg Films Limited | Information & communication | 2024 |
| M & F Decorators Limited | Construction | 2008 |
| M & R Building & Landscaping Ltd | Construction | 2013 |
| M Eastwood Groundworks Limited | Construction | 2005 |
| M Stevens Brickwork Contractors Limited | Construction | 2002 |
| M&A Building Services Ltd | Construction | 2022 |
| M&D Coaches Ltd | Transport & logistics | 2026 |
| M&T Property Group Limited | Real estate | 2025 |
| M&T Property Law Limited | Professional & scientific | 2021 |
| M.A.D.E Ventures Ltd | Arts & recreation | 2022 |
| M.P Window & Gutter Cleaning Services Ltd. | Administrative & support | 2019 |
| M.R Anderson Roofing Ltd | Administrative & support | 2016 |
| Maad Property Ltd | Real estate | 2018 |
| MAC Dents Ltd | Wholesale & retail | 2019 |
| MAC International Media Limited | Professional & scientific | 2003 |
| Mace Access Scaffolding Ltd | Administrative & support | 2016 |
| MAE Automotive Limited | Wholesale & retail | 2025 |
| Make IT Nice Restaurants Ltd | Hospitality | 2024 |
| Making Productions Limited | Arts & recreation | 2014 |
| Mala Properties Limited | Real estate | 2018 |
| Malecky Ltd | Construction | 2020 |
| Mallinson Technology Ltd | Information & communication | 2010 |
| MAN About Style Ltd | Professional & scientific | 2022 |
| Mann Made Makeup Ltd | Other services | 2024 |
| Manor Project Installations Limited | Construction | 2013 |
| Mantle Enterprises Limited | Construction | 2009 |
| Marco Angelini and Co. Limited | Wholesale & retail | 1989 |
| Marcus Sheppard Flooring Limited | Construction | 2006 |
| Marine Scaffolding and Rigging Services Limited | Construction | 2014 |
| Mariners Farm Limited | Real estate | 1962 |
| Mark Pert Films Limited | Information & communication | 2014 |
| Mark Power Electrical Services Limited | Construction | 2014 |
| Market Vault Ltd | Wholesale & retail | 2025 |
| Marketshub Ltd | Financial services | 2023 |
| Marlow Chemical Company Limited | Administrative & support | 1974 |
| Marreli Ltd | Wholesale & retail | 2023 |
| Marrtime Limited | Wholesale & retail | 1989 |
| Mars Capital Limited | Real estate | 2026 |
| Mars Power Group Limited | Construction | 2018 |
| Mars Power Limited | Construction | 2019 |
| Marshall’S Exterior Cleaning Ltd | Administrative & support | 2024 |
| Martifo Compliance Consultants Limited | Administrative & support | 2024 |
| Martinedigit Ltd | Information & communication | 2022 |
| Marunouchi Ltd | Transport & logistics | 2017 |
| Marwell Travel Limited | Transport & logistics | 2012 |
| Masrock Trades Limited | Construction | 2012 |
| Mathsons Ltd | Real estate | 2026 |
| Maureen Court (Freehold) Limited | Real estate | 2007 |
| MAV Property Experts Ltd | Real estate | 2022 |
| Maverick Planet Limited | Professional & scientific | 2005 |
| Mavice Limited | Real estate | 2015 |
| Maxberry Limited | Financial services | 2017 |
| Mayfield Stables and Riding School LLP | | 2020 |
| MB Property (UK) Limited | Real estate | 2012 |
| MBL Property Group Ltd | Construction | 2025 |
| MBM Comms Ltd | Construction | 2022 |
| Mccarron-Millar Limited | Real estate | 2022 |
| MCE Blade Repairs Ltd | Manufacturing | 2026 |
| MCH Carpentry & Joinery Limited | Construction | 2008 |
| MCH Interiors Limited | Construction | 2014 |