| MNH Rupak Limited | Information & communication | 2026 |
| MNP Solutions Limited | Information & communication | 2019 |
| Moat Property Group Limited | Real estate | 2026 |
| Moatclass Builders Limited | Construction | 1976 |
| Mobile Electronic & Security Federation | Other services | 1996 |
| Modera Services Ltd | Wholesale & retail | 2025 |
| Modern Conversions Limited | Real estate | 1999 |
| Modern Graphic Arts Limited | Manufacturing | 1961 |
| Modification Limited | Health & social care | 2018 |
| Mods LAB Ltd | Wholesale & retail | 2024 |
| Modshomes Ltd | Real estate | 2023 |
| Modular Energy Technologies Ltd | Professional & scientific | 2018 |
| Mogours Limited | Administrative & support | 2003 |
| Mohicans Ltd | Professional & scientific | 2017 |
| Mohid Bros Ltd | Wholesale & retail | 2023 |
| Mojubafoluwa Limited | Health & social care | 2008 |
| Molend Limited | Wholesale & retail | 1974 |
| Moles Seeds (U.K.) Ltd | Wholesale & retail | 2007 |
| Moly Green Company Ltd | Construction | 2024 |
| Monara Holdings Limited | Other services | 2022 |
| Mondial Voyage Limited | Administrative & support | 2026 |
| Monetization Valley Limited | Information & communication | 2025 |
| Money Montz Ltd | Financial services | 2026 |
| Moneytree IFA Limited | Financial services | 2005 |
| Monsoon Hotels Limited | Real estate | 2017 |
| Monsoon Restaurant Hainault Ltd | Hospitality | 2025 |
| Monsoon Software Limited | Wholesale & retail | 1998 |
| Montrai Laboratories Ltd | Manufacturing | 2024 |
| Moorcrofts TGM Ltd | Wholesale & retail | 2026 |
| Mooreland Estates Limited | Real estate | 2006 |
| Moqueta Limited | Construction | 2003 |
| Mora-Buck Limited | Hospitality | 2006 |
| Moray Firth Maltings Limited | Extraterritorial | 1998 |
| Morchecks Homes and Properties Ltd | Real estate | 2025 |
| More Corporate Services Limited | Wholesale & retail | 2003 |
| Moreland House Care Home Limited | Health & social care | 2003 |
| Moresure Services Ltd | Construction | 2024 |
| Morethan Plumbing Ltd | Construction | 2006 |
| Morgan Capital Ltd | Professional & scientific | 2021 |
| Morgan Dunn Enterprises Limited | Arts & recreation | 1959 |
| Morino Shinemasters Ltd | Administrative & support | 2025 |
| Morlan Consultants Limited | Wholesale & retail | 1998 |
| Morning Glory Care Home Limited | Health & social care | 2025 |
| Morsh Project Services Limited | Professional & scientific | 2014 |
| Mortgage Pioneers Ltd | Financial services | 2021 |
| Moss Accountancy Services Ltd | Hospitality | 2007 |
| Moto-Tech Limited | Wholesale & retail | 1994 |
| Motor and Car Limited | Wholesale & retail | 2017 |
| Motor Empire London Ltd | Wholesale & retail | 2025 |
| Motor Prestige Ltd | Wholesale & retail | 2018 |
| Motorcycle Tyres UK Limited | Wholesale & retail | 2007 |
| Motorised UK Ltd | Wholesale & retail | 1998 |
| Motortrade Consultants Ltd | Professional & scientific | 2003 |
| Mountain Lake LLP | | 2023 |
| Mountain of Fire and Miracles - Citadel of Grace Ltd | Other services | 2023 |
| Mounthill Engineers Limited | Construction | 1998 |
| Mountview - H2R Ltd | Real estate | 2024 |
| Movesmart Programme Limited | Extraterritorial | 2005 |
| Moving Canvas Limited | Arts & recreation | 2005 |
| Moxom Motorcycles Limited | Construction | 1993 |
| Moyet Holistic Care Ltd | Administrative & support | 2025 |
| Mpid Design Ltd | Professional & scientific | 2007 |
| MPT Interiors Limited | Administrative & support | 2006 |
| MR Bhachu Limited | Financial services | 2022 |
| MR DK Investments Ltd | Real estate | 2024 |
| MR Locks Ltd | Other services | 2002 |
| MR Management Ltd | Real estate | 2025 |
| MR Store Ltd | Wholesale & retail | 2026 |
| MR. Sandwich Limited | Hospitality | 2003 |
| MRB Holdings Ltd | Administrative & support | 2004 |
| Mrcp Syndrome Ltd | Wholesale & retail | 2025 |
| MRL Electrical Ltd | Construction | 2018 |
| MRP UK Services Limited | Administrative & support | 2018 |
| Mrpb Surveying Limited | Professional & scientific | 2006 |
| MRS Mans Ltd | Wholesale & retail | 2025 |
| Mrtr Properties Ltd | Real estate | 2020 |
| MS Heating Ltd | Construction | 2017 |
| MS Joinery & Cabinet Makers Limited | Manufacturing | 2006 |
| MSA Design Limited | Professional & scientific | 2004 |
| MSG Properties Ltd | Real estate | 2023 |
| MSH Business Consultancy Ltd | Professional & scientific | 2023 |
| Msjl Trading Ltd | Real estate | 2006 |
| MSO Investments Limited | Real estate | 2017 |
| MSR Accounting & Tax Consultancy Ltd | Professional & scientific | 2005 |
| MSR for the People | Other services | 2007 |
| MSR Wealth Ltd | Financial services | 2016 |
| MSW Technical Services Ltd | Manufacturing | 2004 |
| Mt&Chl Logistics Limited | Transport & logistics | 2025 |
| MTF Education Ltd | Education | 2022 |
| MTP Communications Limited | Wholesale & retail | 2000 |
| MU Accountants and Advisors Ltd | Professional & scientific | 2024 |
| MU Solutions Limited | Professional & scientific | 2002 |
| MUA Management Services Limited | Professional & scientific | 1995 |
| MUA Property Services Limited | Professional & scientific | 1995 |
| Muba London Limited | Wholesale & retail | 2025 |
| MUC Groups Limited | Wholesale & retail | 2026 |
| Mudasir Fazal Traders Ltd | Wholesale & retail | 2025 |
| Muhammad Ahsan Ayaz Ltd | Wholesale & retail | 2026 |
| Muhammad Huzaifa Amir Limited | Wholesale & retail | 2026 |
| Muhammadabdulrehman Ltd | Wholesale & retail | 2026 |