| MADE4PRESSURE Limited | Administrative & support | 2022 |
| Madpac Limited | Arts & recreation | 2015 |
| Maestrale Consulting Limited | Information & communication | 2020 |
| Maevious Ltd | Education | 2023 |
| Magni Operis Limited | Information & communication | 2024 |
| MAH Project Management Ltd | Professional & scientific | 2013 |
| Mail Shot International Limited | Administrative & support | 1989 |
| Maincore Building Services Limited | Construction | 2002 |
| Maison 21 Limited | Real estate | 2013 |
| MAK Consultancy Services Ltd | Professional & scientific | 2024 |
| Makan Consulting Ltd | Health & social care | 2026 |
| Makbit Financial Services Ltd | Financial services | 2018 |
| Making Connections Limited | Health & social care | 2017 |
| Makrom Properties Ltd | Real estate | 2017 |
| Mala Court Management Company Limited | Households | 2019 |
| Malabar Restaurant Limited | Hospitality | 2007 |
| Malachi Investments Limited | Real estate | 2021 |
| Malawi Food Distributors Limited | Wholesale & retail | 2026 |
| Mandok Finance Limited | Professional & scientific | 2019 |
| Manning House Developments Ltd | Real estate | 2021 |
| Mannings Estates Ltd | Transport & logistics | 2024 |
| Mano and Sons Limited | Construction | 2018 |
| Manor House Resources Ltd | Construction | 2026 |
| Mantravales Limited | Real estate | 2017 |
| Mapall (Holdings) Limited | Information & communication | 2019 |
| Mapall Limited | Information & communication | 2019 |
| Maralodge Estate Management Limited | Other services | 2016 |
| Marcangelo Limited | Information & communication | 2009 |
| Marden Writtle Limited | Construction | 2020 |
| Marheineke Consultancy Limited | Information & communication | 2015 |
| Maria Glezelli Ltd | Manufacturing | 2021 |
| Marie Golden Ltd | Real estate | 2017 |
| Marin Property Investments Ltd | Real estate | 2001 |
| Maringold Estates Ltd | Real estate | 2025 |
| Mark Allen Film Ltd | Information & communication | 2020 |
| Mark Allen Heating Ltd | Construction | 2021 |
| Mark Coden Homes Ltd | Real estate | 2025 |
| Marker Building Contractors Ltd | Construction | 2020 |
| Market Prime Hub Ltd | Wholesale & retail | 2023 |
| Marlbrook Consulting Limited | Professional & scientific | 2025 |
| Marni Limited | Information & communication | 2018 |
| Marsal Strategic Consultancy Limited | Professional & scientific | 2026 |
| MAS Marketing Ltd | Professional & scientific | 2025 |
| Mask Technologies Ltd | Information & communication | 2007 |
| Mason Paul Property Ltd | Real estate | 2020 |
| Masra Partners Limited | Professional & scientific | 2024 |
| Mastercraft Maintenance Limited | Construction | 1998 |
| Masteringminds Limited | Administrative & support | 2014 |
| Matching for Development and Project Management Ltd | Professional & scientific | 2018 |
| Matrix Impex Ltd | Wholesale & retail | 2017 |
| Matt LA Moda Ltd | Wholesale & retail | 2011 |
| Matt Master Construction Ltd | Construction | 2023 |
| Matterpay Ltd | Information & communication | 2016 |
| Matthew Charles Development Ltd | Real estate | 2025 |
| Matthew Charles Services Ltd | Administrative & support | 2017 |
| Maxvalue Solutions Ltd | Wholesale & retail | 2025 |
| Mayford Group Ltd | Administrative & support | 2018 |
| Mayjayy Ltd | Administrative & support | 2024 |
| MAZ Medical Ltd | Health & social care | 2024 |
| MBA Recruitment Ltd | Professional & scientific | 2021 |
| MBH Properties Limited | Real estate | 2005 |
| MBK Technologies Limited | Information & communication | 2003 |
| Mcardle UK Consultancy Ltd | Wholesale & retail | 2008 |
| MCC Structures Limited | Construction | 2020 |
| Mccreary Limited | Other services | 2014 |
| MCL Roofing Ltd | Construction | 2025 |
| MCM Strategic Services Ltd | Professional & scientific | 2025 |
| Mcnab Construction Glassworks Limited | Construction | 2015 |
| MD Acumen Ltd. | Education | 2025 |
| MD Effective Solutions Limited | Real estate | 2016 |
| MD Invest Ltd | Real estate | 2021 |
| MDR Management Services Ltd | Professional & scientific | 2023 |
| Meaburn Partners Ltd | Manufacturing | 2024 |
| Meadows (Helpston) LLP | | 2013 |
| Mebien SPV Ltd | Wholesale & retail | 2023 |
| Medcryst Therapeutics Ltd | Professional & scientific | 2017 |
| Media BET Limited | Administrative & support | 2021 |
| Mediaator Ltd | Professional & scientific | 2013 |
| Medialite Ltd | Information & communication | 2011 |
| Medifort Limited | Administrative & support | 2025 |
| Medihoney (Europe) Ltd | Extraterritorial | 2004 |
| Meditec Systems UK Ltd | Wholesale & retail | 2014 |
| Mediterranean BBQ Grill Ltd | Wholesale & retail | 2023 |
| Medlexa AI Ltd | Information & communication | 2026 |
| Mega Alpha Trading UK Limited | Wholesale & retail | 2017 |
| Melbourne Investments London Limited | Real estate | 2025 |
| Meleagris Limited | Professional & scientific | 1997 |
| Meli Haven Ltd | Health & social care | 2025 |
| Melissa Dawson Ltd | Professional & scientific | 2022 |
| Melkonian Music Publishing UK Limited | Information & communication | 2009 |
| Meraki Hotel Holdings Limited | Hospitality | 2024 |
| Mercurial Limited | Administrative & support | 2015 |
| Merhati Limited | Real estate | 2026 |
| Merinannies Ltd | Administrative & support | 2022 |
| Merlin-Woods Properties Ltd | Real estate | 2019 |
| Mesh Consultants Ltd | Information & communication | 2025 |
| Messy Films Ltd | Information & communication | 2022 |
| Metagrove Ltd | Information & communication | 2026 |
| Metasteps Ltd | Information & communication | 2022 |
| Metin Hilmi & Brokers Limited | Financial services | 2018 |