| Macondo Dream Ltd | Information & communication | 2023 |
| MAD Harper's Cakes Limited | Manufacturing | 2025 |
| Madali Ltd | Other services | 2019 |
| MADE4PAWS Ltd | Manufacturing | 2025 |
| Madeley & District Funeral Services Limited | Extraterritorial | 2012 |
| Madeley Associates Ltd | Professional & scientific | 2022 |
| Madeley Cafe Ltd | Hospitality | 2025 |
| Madeley Test and Repair Ltd | Wholesale & retail | 2017 |
| Madeley Testing Station Ltd | Extraterritorial | 2023 |
| Madhu Kandula Limited | Health & social care | 2025 |
| MAG Group Europe Ltd | Construction | 2022 |
| Mage Consultancy Limited | Professional & scientific | 2024 |
| Mageeka Services Limited | Information & communication | 2013 |
| Magna Specialist Confectioners Limited | Manufacturing | 1972 |
| Magna Technology Solutions Ltd | Information & communication | 2014 |
| Magnitude Limited | Information & communication | 2016 |
| Magnum Security Services Limited | Administrative & support | 2025 |
| Magnum Trans Ltd | Transport & logistics | 2015 |
| Magnvs Ltd | Manufacturing | 2026 |
| Maharaja Indian Restaurant Limited | Hospitality | 2024 |
| Maid Bank Ltd | Administrative & support | 2022 |
| Maiit Solutions Limited | Administrative & support | 2026 |
| Mail Solutions Group Limited | Professional & scientific | 2007 |
| Mail Solutions Limited | Manufacturing | 1989 |
| Mail Solutions Trustees Limited | Administrative & support | 2017 |
| Mail Solutions UK Limited | Manufacturing | 2004 |
| Maintenance Genie Ltd | Construction | 2021 |
| Maintsolve Ltd | Manufacturing | 2024 |
| Maja Transport Ltd | Wholesale & retail | 2025 |
| Majabuild Limited | Construction | 2025 |
| Majestic Distribution (Automotive) Limited | Wholesale & retail | 1998 |
| Maka Machinery UK Limited | Manufacturing | 1998 |
| Makanaka Trading Ltd | Health & social care | 2025 |
| Make IT Make IT Limited | Professional & scientific | 2013 |
| Makeawish Furniture Ltd | Manufacturing | 2021 |
| Makehair Limited | Wholesale & retail | 2025 |
| Makeup Technology Ltd | Manufacturing | 2020 |
| Making IT Happen NOW CIC | Education | 2026 |
| Malavam Ltd | Other services | 2024 |
| Malawi Mania UK Ltd | Agriculture & fishing | 2020 |
| Malcolm Tpjoy Ltd | Health & social care | 2018 |
| Malhi Homes Ltd | Real estate | 2025 |
| Malina Service Ltd | Construction | 2017 |
| Mall Jewellers Ltd | Wholesale & retail | 2016 |
| Mall UK Properties Ltd | Real estate | 2025 |
| Malmolit Ltd | Wholesale & retail | 2019 |
| Malt Properties UK Limited | Real estate | 2024 |
| Malt Shovel Salop Ltd | Hospitality | 2024 |
| Maltings Developments Limited | Construction | 2013 |
| Mamaruga Limited | Manufacturing | 2019 |
| Mammalucia Streetfood Ltd | Hospitality | 2022 |
| Manageourclub Limited | Information & communication | 2025 |
| Manatee Studio Ltd | Construction | 2023 |
| Mandare Limited | Information & communication | 2019 |
| MANDURIA1978 Ltd | Hospitality | 2025 |
| Manenda & Co Ltd | Real estate | 2013 |
| Mangal Kebab Limited | Other services | 2016 |
| MANGE3.COM Ltd | Information & communication | 2018 |
| Maninplace Estate Community Interest Company | Real estate | 2006 |
| Manj Air Conditioning Ltd | Construction | 2023 |
| Mankycarrot Limited | Extraterritorial | 1995 |
| Mann Freightways Ltd | Transport & logistics | 2015 |
| Mannings Supermarkets Limited | Wholesale & retail | 2011 |
| Mannleys Group Limited | Financial services | 2026 |
| Manor Convenience Store Ltd | Wholesale & retail | 2020 |
| Manufacturing Consulting Ltd | Professional & scientific | 2016 |
| Manz & Sons Ltd | Real estate | 2024 |
| Maplestory Capital Limited | Real estate | 2023 |
| Marbjjess Limited | Health & social care | 2021 |
| Marble Food Ltd | Hospitality | 2024 |
| Marbleina Holdings Limited | Financial services | 2017 |
| Marbleina Limited | Wholesale & retail | 2003 |
| Marcello Hunt Contracting Ltd | Information & communication | 2022 |
| Mardeea Construction Ltd | Construction | 2019 |
| Marena Property UK Ltd | Real estate | 2025 |
| Margo Finishing Ltd | Construction | 2015 |
| Mari Support Services Limited | Health & social care | 2024 |
| Mari-Sher Limited | Construction | 2013 |
| Maricar Butiong Limited | Wholesale & retail | 2021 |
| Marieba Ltd | Other services | 2019 |
| Marimoo Ltd | Administrative & support | 2020 |
| Marina Seaview Ltd | Hospitality | 2020 |
| Marine Elegance Ltd | Information & communication | 2016 |
| Marine Plaza Limited | Hospitality | 2025 |
| Marinus Holdings Limited | Financial services | 2022 |
| Mariteks Ltd | Other services | 2018 |
| Mark 61 Limited | Construction | 2026 |
| Mark Coupe Limited | Professional & scientific | 2021 |
| Mark Taylor Support Ltd | Education | 2018 |
| Mark Wigley Carpentry Ltd | Construction | 2024 |
| Markefy Ltd | Wholesale & retail | 2026 |
| Marketing & Training Solutions Ltd | Professional & scientific | 2002 |
| Marketing at the Mill Limited | Professional & scientific | 2000 |
| Marni Consultancy Ltd | Information & communication | 2015 |
| Marnwood Acquisitions Ltd | Agriculture & fishing | 2023 |
| Marnwood Estates Limited | Real estate | 2026 |
| Marnwood Investments Limited | Real estate | 2022 |
| Marnwood Properties Limited | Real estate | 2000 |
| Marsavela Construction Limited | Construction | 2013 |
| Marshall Harmony Limited | Administrative & support | 2017 |