| Luke Goulden Personal Trainer Ltd | Arts & recreation | 2018 |
| Lumina Tech Group Limited | Professional & scientific | 2024 |
| Lumle Holidays Ltd | Administrative & support | 2011 |
| Lunica Limited | Professional & scientific | 2019 |
| Luxe Coaches Limited | Transport & logistics | 2018 |
| Luxury Wines Ltd | Administrative & support | 2016 |
| Luxx Transport Limited | Wholesale & retail | 2021 |
| M & H Decorators Limited | Construction | 2018 |
| M & M Brothers Ltd | Transport & logistics | 2014 |
| M Bhardwaj Anaesthetic Ltd | Health & social care | 2015 |
| M C R B Investments Ltd | Real estate | 2018 |
| M.C.H. (Mini-Buses) Limited | Transport & logistics | 1990 |
| MAC & NJT Limited | Other services | 2024 |
| Madebymase Ltd | Professional & scientific | 2026 |
| Madhava Pharm Limited | Wholesale & retail | 2013 |
| Madrunways Ltd | Education | 2025 |
| Magi Capital Credit Ltd | Professional & scientific | 2024 |
| Maicenrhys Limited | Households | 2022 |
| Main Drive, Hawthorn Mews and Woodland Grange Residents Management Company Limited | Households | 2015 |
| Mainline Executive Cars Ltd | Transport & logistics | 2020 |
| MAK Homes Ltd | Real estate | 2025 |
| Management Property Solutions Ltd | Construction | 2020 |
| Mandeep Atwal Consulting Limited | Professional & scientific | 2023 |
| Mangat Ventures Limited | Real estate | 2020 |
| Manisha Coaching Ltd | Education | 2020 |
| Manor Environmental Ltd. | Transport & logistics | 2014 |
| Manor Equine Ltd | Transport & logistics | 2018 |
| Manor Legal Associates Limited | Professional & scientific | 2023 |
| Manor Tippers Ltd | Transport & logistics | 2018 |
| Mansoor Property Investments Limited | Real estate | 2022 |
| Marathon Air Cargo Limited | Transport & logistics | 1989 |
| Markov Consulting Ltd | Professional & scientific | 2023 |
| Marmina Ltd | Administrative & support | 2022 |
| Marsden Care Limited | Health & social care | 2025 |
| Maruti Home Investments Ltd | Real estate | 2023 |
| Marvel Motorcycles Limited | Wholesale & retail | 2012 |
| Masonwood Build Ltd | Construction | 2015 |
| Maximus Meld Ltd. | Real estate | 2022 |
| Mbst International Ltd | Information & communication | 2018 |
| Mclean Inns Limited | Hospitality | 2000 |
| MD Bexley Limited | Real estate | 2022 |
| Meer Couriers and Transport Ltd | Transport & logistics | 2026 |
| MEN & Motors Limited | Information & communication | 2017 |
| Merchant Credit Ltd | Administrative & support | 2017 |
| Merto Software Solutions Ltd | Professional & scientific | 2025 |
| Meta Health Solutions Ltd | Health & social care | 2022 |
| Metaboards Holdings Ltd | Professional & scientific | 2024 |
| Metal Inspirations Limited | Manufacturing | 2000 |
| Meva Construction Ltd | Construction | 2020 |
| MFK Consulting Limited | Professional & scientific | 2012 |
| MGA Contracts Limited | Construction | 2005 |
| MH Accounting Limited | Administrative & support | 2019 |
| MHS Solutions Ltd | Manufacturing | 2018 |
| Micrologic Computer Supplies Limited | Wholesale & retail | 1998 |
| Midcore Group Ltd | Administrative & support | 2016 |
| Midland Tree Surgeons Limited | Administrative & support | 2018 |
| Midsun Health Ltd | Wholesale & retail | 2025 |
| Miles of London Ltd | Transport & logistics | 2025 |
| MILES4SMILES C.I.C. | Health & social care | 2023 |
| Milestone Installation Ltd | Construction | 2020 |
| Millstone Assets Ltd | Professional & scientific | 2022 |
| Mina Property Holdings Ltd | Financial services | 2023 |
| Minouce Limited | Real estate | 2026 |
| Miwa Limited | Real estate | 1920 |
| MIX Autotech Ltd | Wholesale & retail | 2026 |
| MJ Watches London Limited | Wholesale & retail | 2025 |
| MJ. Executive Ltd | Transport & logistics | 2018 |
| MJD Joinery Ltd | Manufacturing | 2021 |
| Mk-Cousins Ltd | Wholesale & retail | 2026 |
| MKS Invests Limited | Real estate | 2023 |
| Mlassa Ltd | Real estate | 2017 |
| Mogli Labs UK Private Ltd | Wholesale & retail | 2020 |
| Montague Waste Management Ltd | Water & waste | 2025 |
| Moon and Stars Glamping Ltd | Hospitality | 2020 |
| Moonlight Global Ltd | Transport & logistics | 2026 |
| Morinergy Ltd | Manufacturing | 2026 |
| MORTGAGES121 Limited | Financial services | 2013 |
| Mosaic Hospitality Recruitment Ltd | Administrative & support | 2024 |
| Mosaic Music Ensemble Ltd | Arts & recreation | 2023 |
| Motordex Limited | Wholesale & retail | 2025 |
| Move Inn Financial Services Ltd | Financial services | 2025 |
| Move Inn Iver Lettings Ltd | Real estate | 2024 |
| Movie Camera Support Limited | Manufacturing | 2003 |
| MPW Chauffeurdrive Ltd | Transport & logistics | 2008 |
| MPW Security Solutions Ltd | Administrative & support | 2014 |
| MR. Haircare Limited | Other services | 2015 |
| Mr.Boilers Services Limited | Wholesale & retail | 2022 |
| MRM Digital Ltd | Professional & scientific | 2025 |
| Mtar Limited | Transport & logistics | 2017 |
| MTB Groundwork Limited | Construction | 2000 |
| Multani Estate Management Limited | Construction | 2018 |
| Multi Brands Outlet Ltd | Wholesale & retail | 2013 |
| Munch Crunch Ltd | Hospitality | 2020 |
| Mundh Ltd | Information & communication | 2025 |
| Music Mandi Ltd | Information & communication | 2025 |
| Muttu & Sandhu Limited | Health & social care | 2025 |
| MWC Accounting Ltd | Professional & scientific | 2026 |
| My Center Ltd | Professional & scientific | 2023 |
| My Islamic Celebration Ltd | Wholesale & retail | 2022 |
| Mycareadmin Limited | Information & communication | 2015 |