| Mace Homecare Service Ltd | Health & social care | 2019 |
| Mace Rental Homes Ltd | Health & social care | 2024 |
| Mace Trails Ltd | Wholesale & retail | 2020 |
| Macedo Gardening Services Ltd | Administrative & support | 2024 |
| Macilvin Moore Reveres Limited Liability Partnership | | 2001 |
| Mackinaw Limited | Transport & logistics | 2010 |
| Mackpen Ltd | Professional & scientific | 2025 |
| Maconse Ltd | Information & communication | 2018 |
| Macov Group Ltd | Construction | 2025 |
| Macovei Ltd | Construction | 2011 |
| Macro Vision Limited | Real estate | 2017 |
| Macs Investment Ltd | Real estate | 2016 |
| Macy Eggs Ltd | Hospitality | 2026 |
| MAD BEE Media Ltd | Information & communication | 2014 |
| Madalin Management Limited | Wholesale & retail | 2018 |
| Madan Digital Limited | Information & communication | 2016 |
| Madani Maison Ltd | Extraterritorial | 2011 |
| Madd Wellness Ltd | Other services | 2022 |
| Maddyzones Ltd | Information & communication | 2025 |
| Made Moments UK Limited | Arts & recreation | 2023 |
| Madeleine Copin Limited | Education | 2025 |
| Madena Motorist Ltd | Wholesale & retail | 2013 |
| Madhaparia Properties Limited | Real estate | 2015 |
| Madhav AI Technologies Ltd | Information & communication | 2026 |
| Madhav Construction Limited | Construction | 2025 |
| Madhav Estate Ltd | Real estate | 2025 |
| Madhav Trade Ltd | Wholesale & retail | 2026 |
| Madhu Bhachu Ltd | Education | 2019 |
| Madhuri Consultancy Limited | Information & communication | 2025 |
| Madina Cleaning Services Ltd | Administrative & support | 2026 |
| Madina Properties (Herts ) Limited | Households | 2021 |
| Madina Supermarket Limited | Wholesale & retail | 2014 |
| Madison Heights Residents Company Limited | Households | 2013 |
| Madison Perfume Limited | Wholesale & retail | 1997 |
| Maditx Solutions Ltd | Information & communication | 2025 |
| Madras Iyer's Limited | Other services | 2011 |
| Madsm Limited | Information & communication | 2018 |
| Maeva Limited | Administrative & support | 2012 |
| MAF Contracts Ltd | Construction | 2015 |
| MAG Builders Ltd | Construction | 2018 |
| Magazin Romanesc London Ltd | Construction | 2020 |
| Magdalena Spink Ltd | Wholesale & retail | 2025 |
| Magenta Life Limited | Professional & scientific | 2017 |
| Magenta Smiley Limited | Education | 2025 |
| Magi Excellent Services Ltd | Administrative & support | 2017 |
| Magic Car Wash Services Ltd | Administrative & support | 2023 |
| Magic Cleaning Services Group Ltd | Administrative & support | 2025 |
| Magic in the Oven PVT Ltd | Manufacturing | 2016 |
| Magic Meal Ltd | Professional & scientific | 2026 |
| Magic Momentum Limited | Construction | 2026 |
| Magic Touch Development Limited | Financial services | 2015 |
| Magical Napkins West Ltd | Hospitality | 2024 |
| Magicbrick Estate Agents Ltd | Real estate | 2016 |
| Magicbrick Estates Ltd | Households | 2021 |
| Magiclink Properties Ltd | Real estate | 2020 |
| Magictree Superfoods Ltd | Wholesale & retail | 2021 |
| Magik Homes Limited | Real estate | 2023 |
| Magins Limited | Construction | 2012 |
| Magna IT Solutions Limited | Information & communication | 2017 |
| Magna Property and Estates Ltd | Construction | 2025 |
| Magnesic Ltd | Wholesale & retail | 2026 |
| Magnet Investments Limited | Real estate | 2003 |
| Magnet Property Ltd | Real estate | 2019 |
| Magnify LAB Ltd | Professional & scientific | 2015 |
| Magnoglide Systems Limited | Information & communication | 1999 |
| Magnolia MAE Films Limited | Information & communication | 2013 |
| Magnolia MAE Firebrand Limited | Information & communication | 2021 |
| Magnolia MAE Productions Limited | Information & communication | 2021 |
| Magnolia Place Harrow Management Limited | Households | 2012 |
| Magnolia Terrace Limited | Real estate | 2002 |
| Magnum Estate Company Limited | Real estate | 1981 |
| Magnum Industrial Limited | Real estate | 1987 |
| Magnus Fire Ltd | Construction | 2017 |
| Magrot Ltd | Information & communication | 2013 |
| Magsonic Properties Limited | Real estate | 2025 |
| Maha 2021 Limited | Extraterritorial | 2021 |
| Maha Selvan Ltd | Real estate | 2025 |
| Maha Shila Group Ltd | Construction | 2026 |
| Mahaan Solutions Ltd | Information & communication | 2022 |
| Mahaco Ltd | Professional & scientific | 2024 |
| Mahant Enterprise Ltd | Transport & logistics | 2023 |
| Mahant Real Estate Ltd | Real estate | 2022 |
| Mahaprabhuji Properties Ltd | Real estate | 2020 |
| Maharaaja Enterprise Limited | Wholesale & retail | 2018 |
| Maharaja Capital Ltd | Information & communication | 2015 |
| Maharanni's Ltd | Manufacturing | 2023 |
| Mahas Empire Ltd | Real estate | 2020 |
| Mahashri Limited | Real estate | 2025 |
| Mahason Investments Limited | Real estate | 2019 |
| Mahason Limited | Wholesale & retail | 2005 |
| Mahason Retail Limited | Wholesale & retail | 2024 |
| Mahaveer Workforce and Business Consultancy Limited | Professional & scientific | 2025 |
| Mahavir Foundation Limited | Health & social care | 1987 |
| Mahavir Healthcare Limited | Health & social care | 2021 |
| Mahavir Motors Limited | Wholesale & retail | 2024 |
| Mahavir Properties Ltd | Real estate | 2018 |
| Mahavir Spurriergate Limited | Real estate | 2025 |
| Mahek Creation Ltd | Wholesale & retail | 2025 |
| Mahesh & Sons Ltd | Wholesale & retail | 2025 |
| Mahesh Pharmaceutical Limited | Wholesale & retail | 2023 |