| Luxor AV Ltd | Arts & recreation | 2020 |
| Luxor Music Limited | Other services | 2018 |
| Luxtherm Ltd | Professional & scientific | 2025 |
| LXD Property Group Ltd | Real estate | 2020 |
| Lyceum Limited | Education | 2020 |
| Lyons Enterprises Ltd | Real estate | 2018 |
| M & a Wealth Management Limited | Financial services | 2017 |
| M & H Classic & Performance Ltd | Wholesale & retail | 2024 |
| M & M Hospitality (London) Ltd | Professional & scientific | 2024 |
| M Holdings Ltd | Other services | 2024 |
| M Sandhu & Sons Construction Limited | Construction | 2025 |
| M Stone Developments Limited | Construction | 2008 |
| M W Plumbers Ltd | Construction | 2009 |
| M&A First Capital Ltd | Other services | 2025 |
| M&A Immigration Law Services Limited | Professional & scientific | 2025 |
| M&J Infinity UK Ltd | Professional & scientific | 2025 |
| M&M Orion Ltd | Real estate | 2022 |
| M&P UK Property Ltd | Hospitality | 2023 |
| M&R Investments Group Ltd | Real estate | 2021 |
| M.E. Mechanical Handling Limited | Professional & scientific | 1967 |
| Maaannapoorna IT Sols. Ltd. | Information & communication | 2024 |
| Maccon Management Services (UK) Limited | Real estate | 1999 |
| Macgiolla Overseas Mercantile Holdings Ltd | Financial services | 2026 |
| MAD MUG Lady Ltd | Manufacturing | 2014 |
| Made of Waste Ltd | Professional & scientific | 2021 |
| Madental Ltd | Health & social care | 2017 |
| Madras Real Estate Company Limited | Construction | 2020 |
| Magic Motion Simulators Ltd | Arts & recreation | 2023 |
| Magic Motors 23 Ltd | Wholesale & retail | 2016 |
| Magic Repair Art Ltd | Construction | 2025 |
| Magna AI Ltd | Information & communication | 2024 |
| Magna Carta Residential Limited | Real estate | 2024 |
| Magnolia Rackets Club Ltd | Arts & recreation | 2025 |
| Maid to Perfection Clean Ltd | Administrative & support | 2021 |
| Maid to Perfection Domestic Limited | Administrative & support | 2026 |
| Maidenhead Aquatics 1 LLP | | 2021 |
| Maidenhead Aquatics 2 LLP | | 2010 |
| Maidenhead Aquatics 3 LLP | | 2010 |
| Maidenhead Aquatics 4 LLP | | 2010 |
| Maidenhead Aquatics 5 LLP | | 2010 |
| Maidenhead Aquatics 6 LLP | | 2010 |
| Maidenhead Aquatics Distribution Limited | Administrative & support | 2010 |
| Maidenhead Aquatics Limited | Professional & scientific | 1995 |
| Mainpay Limited | Professional & scientific | 2006 |
| Maison Mere Property Investments Limited | Real estate | 2019 |
| Malek Limited | Professional & scientific | 2013 |
| Malitholo Ltd | Real estate | 2024 |
| Mamori UK Ltd | Real estate | 2025 |
| Manatee Rescue League Ltd | Other services | 2024 |
| Manerium Malleus Ltd | Other services | 2023 |
| Mangnus Property Ltd | Real estate | 2026 |
| Manis Property Group Ltd | Real estate | 2019 |
| Mantons Properties Capital Ltd | Real estate | 2018 |
| Mantons Properties Llord Ltd | Real estate | 2018 |
| Marba Ltd | Real estate | 2021 |
| Marbagege Ltd | Construction | 2023 |
| Marble and Stone Limited | Construction | 2026 |
| Marcam Europe Ltd | Wholesale & retail | 2018 |
| Marcel Maranatha Ltd | Other services | 2023 |
| Margaretta Corporate Secretaries Limited | Professional & scientific | 1989 |
| Marianne Schweiger Stiftung Ltd | Other services | 2023 |
| Marida Limited | Professional & scientific | 2012 |
| Marlin Global Invest Ltd | Financial services | 2021 |
| Marouf Homes Ltd | Real estate | 2020 |
| Mars Empire Ltd | Other services | 2018 |
| Martinez Mielot & Crespo Maclennan Ltd | Other services | 2015 |
| Martinsson Capital Ltd | Real estate | 2021 |
| Mary Wilson Limited | Wholesale & retail | 2025 |
| Mase Capital Limited | Real estate | 2017 |
| Mason Freeman & Forbes Limited | Information & communication | 2023 |
| Maspro Safety Solutions Ltd | Wholesale & retail | 2025 |
| Massive FX Limited | Manufacturing | 2026 |
| Masteq Safety Solutions Ltd | Wholesale & retail | 2025 |
| MATCHA2YOU Limited | Wholesale & retail | 2025 |
| Matea Sea Ltd | Agriculture & fishing | 2022 |
| Mathur & Mathur Ltd | Health & social care | 2014 |
| Matt Wood Flooring Ltd | Wholesale & retail | 2022 |
| Mauger Residential Ltd | Real estate | 2025 |
| Mauna KEA Invest Ltd | Real estate | 2024 |
| Mavan Services Ltd | Administrative & support | 2026 |
| Maverick Housing Ltd | Real estate | 2021 |
| Maxstone Realty Ltd | Real estate | 2025 |
| Maya Underground Detection and Mapping Ltd | Construction | 2017 |
| Mayfield Watford Management Limited | Real estate | 2019 |
| Mayoris Ltd | Professional & scientific | 2022 |
| MB Repairs Limited | Extraterritorial | 2008 |
| MC International Ltd | Wholesale & retail | 2023 |
| Mccabe Property Investments Ltd | Real estate | 2022 |
| Mcharo Consultancy Limited | Construction | 2017 |
| MCK Commerce Ltd | Wholesale & retail | 2016 |
| MCL Pro Limited | Information & communication | 2023 |
| MCM Real Estate Ltd | Real estate | 2018 |
| MCM Real Estate Ventures Ltd | Real estate | 2018 |
| Mcnaha Limited | Health & social care | 2015 |
| MDB Real Estate Ltd | Real estate | 2021 |
| MDI Properties Limited | Real estate | 2024 |
| Mds-Planning Ltd | Construction | 2026 |
| Meadlake Services Limited | Professional & scientific | 2024 |
| Meadow Healthcare Limited | Wholesale & retail | 2022 |
| Med-E-Tech Limited | Wholesale & retail | 2016 |