| Malayapillay Consulting Ltd | Professional & scientific | 2018 |
| Malda Group Limited | Financial services | 2017 |
| Malina Properties Limited | Real estate | 2018 |
| Malix Services Ltd | Transport & logistics | 2022 |
| Malone Financial Services Ltd | Financial services | 2009 |
| Maloney’S Plumbing & Heating Merchants Limited | Wholesale & retail | 2026 |
| MAN and Van Epsom Downs Waste Clearance Ltd | Transport & logistics | 2022 |
| MAN MOT and Motors Limited | Manufacturing | 2020 |
| Mana DO Cerrado Brazilian Food Ltd | Hospitality | 2025 |
| Managed Security Services Ltd | Information & communication | 2001 |
| Managewell Limited | Real estate | 2005 |
| Manakai Consulting Ltd | Wholesale & retail | 2019 |
| Mandalina Limited | Hospitality | 2017 |
| Mandar Assets Ltd | Real estate | 2022 |
| Mandar Investments Ltd | Real estate | 2022 |
| Mandar Solutions Ltd | Manufacturing | 2015 |
| Mandy Saligari Limited | Health & social care | 2025 |
| Mangata Consulting Ltd | Professional & scientific | 2023 |
| Mangrove Homes Ltd | Real estate | 2024 |
| Manick Builders Limited | Construction | 2025 |
| Manis by Mais Ltd | Other services | 2024 |
| Mann Property Investments Ltd. | Real estate | 2017 |
| Mann Property Partners Ltd | Real estate | 2025 |
| Manners EPC Limited | Professional & scientific | 2021 |
| Manners Residential Holdings Limited | Financial services | 2025 |
| Manners Residential Limited | Real estate | 2011 |
| Manny's Kitchen CIC | Hospitality | 2022 |
| Manochi Limited | Information & communication | 2022 |
| Manor Green Advisory Ltd | Real estate | 2023 |
| Manor House Thurso Ltd | Hospitality | 2019 |
| Manor Park Cafe Ltd | Hospitality | 2019 |
| Manor Park Holdings Limited | Construction | 2016 |
| Manor Ridgeway Limited | Real estate | 2015 |
| Manthorpe Grint Limited | Professional & scientific | 2006 |
| Manthorpe Grint Property Partners Limited | Real estate | 2011 |
| Manthorpe Grint Property Partners NO2 Limited | Real estate | 2012 |
| Manthry Lindsay Ltd | Administrative & support | 2024 |
| Manya Engineering Consultants Ltd | Professional & scientific | 2013 |
| Manzila Trade Ltd | Transport & logistics | 2020 |
| MAP Automotive Mobile Mechanics Ltd | Wholesale & retail | 2020 |
| Mapd D16PP Holdings Limited | Financial services | 2026 |
| Maple Gardens RTM Company Limited | Households | 2025 |
| Maples Consultants Ltd | Professional & scientific | 2021 |
| Mara Accountancy Ltd | Professional & scientific | 2025 |
| Marathon Sports Foundation Limited | Arts & recreation | 2007 |
| Marathon Window Company Limited | Manufacturing | 2008 |
| Maraway Construction Services Limited | Professional & scientific | 2023 |
| Maraway Property Limited | Real estate | 2021 |
| Marblewinner Ltd | Arts & recreation | 2025 |
| Marc LED Ltd | Wholesale & retail | 2010 |
| Marco Trans Limited | Transport & logistics | 2014 |
| Marco UK Ltd | Transport & logistics | 2007 |
| Mardelplato Ltd | Hospitality | 2013 |
| Mariners Court (Hayling Island) Limited | Households | 1982 |
| Mariners Hotel Mariners Square Ltd | Hospitality | 2024 |
| Marivek Limited | Professional & scientific | 2014 |
| Marjon Business Services Limited | Financial services | 2026 |
| Mark Anthony Estate Agents Limited | Real estate | 2015 |
| Mark's Fireplace Installation Limited | Construction | 2021 |
| Market Capital Technology Ltd | Information & communication | 2016 |
| Marketingkik Ltd | Extraterritorial | 2021 |
| Markham DRY Lining Limited | Construction | 2009 |
| Marks Transport (Surrey) Limited | Transport & logistics | 2012 |
| Marshall Creative Limited | Professional & scientific | 2021 |
| Marshalls Court RTM Company Ltd | Households | 2018 |
| Marshels & Sons Limited | Extraterritorial | 2018 |
| Marshels of Farnham Limited | Construction | 1992 |
| Marshels of London Limited | Professional & scientific | 2004 |
| Marten and Carnaby Ltd. | Real estate | 2003 |
| Martini Property Management Ltd | Real estate | 2025 |
| Marvel Block Limited | Construction | 2024 |
| Marvig Ltd | Construction | 2017 |
| Mashattan Ltd | Wholesale & retail | 2022 |
| Maskell Investments Egmont Ltd | Real estate | 2024 |
| Maskell Investments Limited | Construction | 2017 |
| Maskell Investments Oakdene Limited | Real estate | 2023 |
| Maskell Investments Tannery Limited | Construction | 2022 |
| Mason & Vale Property Limited | Real estate | 2025 |
| Masonbell Scaffolding Ltd | Construction | 2010 |
| Masons Court (Management) Limited | Households | 1994 |
| Massoft Ltd | Information & communication | 2013 |
| Mast ICT Limited | Information & communication | 2010 |
| Master School Portraits Limited | Professional & scientific | 1999 |
| Masterpiece Systems Limited | Information & communication | 1997 |
| Masters of Draghounds & Bloodhounds Alliance Limited | Arts & recreation | 2023 |
| Mastertechs-Chessington Limited | Wholesale & retail | 2010 |
| Matchfit Climb Ltd | Education | 2024 |
| Matcon Paving Ltd | Construction | 2017 |
| Math UK Film Limited | Information & communication | 2018 |
| Mathematika Limited | Education | 2020 |
| Mathias and Co UK Ltd | Households | 2010 |
| Maths for Life Limited | Information & communication | 2005 |
| Matraxis Limited | Information & communication | 2002 |
| Matrix Electricity Service Ltd | Construction | 2022 |
| Matt Brooks HR Network Limited | Financial services | 2014 |
| Matt Hammond Consultancy Ltd | Professional & scientific | 2005 |
| Matt Powell Ltd | Professional & scientific | 2022 |
| Matthew Dewar Carpentry Limited | Manufacturing | 2016 |
| Mattinson Consultancy Ltd | Information & communication | 2019 |
| Maurice Homes Limited | Households | 2013 |