| M Square Developments Ltd | Construction | 2017 |
| M Square Investments Limited | Real estate | 2023 |
| M V Promotions Limited | Arts & recreation | 2003 |
| M.G. Brighouse Limited | Real estate | 2011 |
| MA Holdings International Limited | Wholesale & retail | 2024 |
| Macvet Cattle Communications Limited | Professional & scientific | 2016 |
| Madd Digital Limited | Financial services | 2025 |
| Magnit Global GRI IP Limited | Information & communication | 2004 |
| Magnit Global GRI Limited | Information & communication | 2003 |
| Magnit Global UK Bidco Limited | Financial services | 2022 |
| Magnit Global UK Limited | Professional & scientific | 2005 |
| Magnit Global UK WFQ Limited | Administrative & support | 2006 |
| Magnolia Drive (Holbeach Drove) Management Company Ltd | Households | 2024 |
| Magnus (Blackheath) Limited | Hospitality | 2008 |
| Magnus (Buzzard) Limited | Real estate | 2008 |
| Magnus Properties (Hayes) Limited | Hospitality | 2006 |
| Magpie Asset Management Limited | Real estate | 2016 |
| MAH Properties Limited | Real estate | 2006 |
| Maison Grace UK Ltd | Professional & scientific | 2025 |
| Maker Home Ltd | Wholesale & retail | 2025 |
| Malcraft Properties Limited | Households | 1994 |
| Mallory Financial Limited | Financial services | 2019 |
| Mallory Trading Limited | Professional & scientific | 2018 |
| Mamelok Corp Ltd | Information & communication | 2023 |
| Maml Contracts Limited | Wholesale & retail | 2025 |
| MAN of Leisure Limited | Real estate | 2023 |
| MAN on COW Ltd | Wholesale & retail | 2026 |
| Manchester Driving Academy Private Limited | Education | 2011 |
| Mangoletsi Used Cars Limited | Professional & scientific | 1988 |
| Mania Motors Limited | Manufacturing | 2011 |
| Manor Architecture Ltd | Professional & scientific | 2022 |
| Manor Court Flats (Knutsford) Limited | Households | 1974 |
| Manor Farm Tabley Ltd. | Hospitality | 2016 |
| Maplewood Flats Management Limited | Extraterritorial | 2016 |
| Maraleem Limited | Financial services | 2024 |
| Marcus T Enterprises Limited | Arts & recreation | 2001 |
| Margao Ltd | Hospitality | 2024 |
| Maria Mattress Ltd | Wholesale & retail | 2022 |
| Mark a Smith Consulting Limited | Professional & scientific | 2021 |
| Mark Bohannon Ltd | Professional & scientific | 2026 |
| Mark Buckley Ltd | Real estate | 2024 |
| Mark Holden Consultancy Limited | Professional & scientific | 2014 |
| Market Hall Ventures Limited | Real estate | 2023 |
| Marketing Knutsford Limited | Professional & scientific | 2006 |
| Marks Holiday Parks Limited | Financial services | 2022 |
| Marlowe DC Pension Trustees Limited | Other services | 2004 |
| Marlowe Holdings Investments Limited | Professional & scientific | 1948 |
| Marlowe Holdings Life Assurance Trustees Limited | Other services | 1994 |
| Marlowe Holdings Limited | Professional & scientific | 2009 |
| Marlowe Investments Limited | Extraterritorial | 1945 |
| Marson Health Ltd | Wholesale & retail | 2023 |
| Marthen Holdings Limited | Professional & scientific | 2024 |
| Martin Howden Limited | Professional & scientific | 2004 |
| Martin Hurst Limited | Real estate | 2018 |
| Martindale Property Services Limited | Real estate | 1998 |
| Massey Foundations & Piling Limited | Construction | 2008 |
| Matata Solutions Limited | Professional & scientific | 2023 |
| Matchcourt Limited | Education | 1987 |
| Matthew a Potts & Sons Limited | Other services | 2016 |
| Maxxo.Ai Limited | Information & communication | 2025 |
| MB Acquisition 103 Limited | Hospitality | 2025 |
| MBA Consulting Engineers Limited | Professional & scientific | 1994 |
| MBH TAP & Shop Limited | Manufacturing | 2017 |
| Mccx Group Ltd | Financial services | 2020 |
| Mcgregor Plant Ltd | Construction | 2014 |
| Mcintosh Coaching Ltd | Arts & recreation | 2025 |
| Mckay Medical Communications Limited | Administrative & support | 2022 |
| MDP Legal Services Limited | Professional & scientific | 2018 |
| MDR Creative (UK) Ltd | Professional & scientific | 2014 |
| Meadow at Moss Lane Limited | Wholesale & retail | 2023 |
| Medicex Limited | Health & social care | 2023 |
| Mediclip Ltd | Information & communication | 2025 |
| Medics' Money Limited | Professional & scientific | 2014 |
| Melissa Porter Limited | Information & communication | 2003 |
| Melius Acquisitions Ltd | Professional & scientific | 2025 |
| Melksham Link Limited | Transport & logistics | 2017 |
| Melodik Solutions Limited | Information & communication | 2025 |
| Merchandise & More Limited | Wholesale & retail | 2015 |
| Mere Court Hotel Ltd | Hospitality | 2026 |
| Mere Farm Pool Limited | Financial services | 2024 |
| Mere Hall Management Company Limited | Households | 1999 |
| Meredith Accountancy Services Limited | Professional & scientific | 2003 |
| Merehaven Management Limited | Households | 1990 |
| Merry FOX Stud Limited | Agriculture & fishing | 2006 |
| Merrydale Manor Country Estate Limited | Hospitality | 2020 |
| Merrydale Manor Event Planning Ltd | Administrative & support | 2019 |
| Merrydale Manor Lodges Ltd | Hospitality | 2020 |
| Mesoestetic PH Limited | Wholesale & retail | 2023 |
| Mesoestetic UK & Ireland Limited | Wholesale & retail | 2021 |
| Met-Fin Ltd | Financial services | 2015 |
| Metal and Pipeline Endurance Limited | Extraterritorial | 1954 |
| Metalbeat Ltd | Administrative & support | 2006 |
| Metro Hub Ltd | Hospitality | 2024 |
| Metro Inns (Mirfield) Ltd | Hospitality | 2013 |
| Metro Inns (Teesside) Limited | Real estate | 2006 |
| Metro Inns A3 Limited | Hospitality | 2013 |
| Metro Inns Group Ltd | Administrative & support | 2021 |
| Metro Motels (Radnor) Ltd | Administrative & support | 2016 |
| Metro Motels Ltd | Hospitality | 2013 |
| Metro Northern Limited | Hospitality | 2016 |