| Medi-Plinth Equipment Limited | Manufacturing | 2007 |
| Medical Cure Limited | Professional & scientific | 2015 |
| Medical Marvels Limited | Wholesale & retail | 2024 |
| Medicine 18 Limited | Hospitality | 2018 |
| Medior Management Ltd | Professional & scientific | 2003 |
| Meds & Pills Ltd | Wholesale & retail | 2017 |
| Medtech Group Ltd | Wholesale & retail | 2020 |
| Mega Corporation Ltd | Professional & scientific | 2025 |
| Megalith Flinnt Holdings Limited | Financial services | 2025 |
| Melbird Invest Ltd | Real estate | 2019 |
| Melrose Property Rentals Ltd | Real estate | 2019 |
| Memabui Ltd | Financial services | 2021 |
| Menthe Conservation Ltd | Other services | 2024 |
| Meridian (Wokingham) Management Company Limited | Real estate | 2008 |
| Merlin International Television Limited | Information & communication | 1987 |
| Mersey Lets Ltd | Real estate | 2006 |
| Metamorph Consulting Limited | Professional & scientific | 2016 |
| Metaversal Infinity Ltd | Information & communication | 2021 |
| Metric Office Furniture Limited | Wholesale & retail | 1970 |
| Mewshall Interiors Limited | Wholesale & retail | 1999 |
| MG Capital Properties Ltd | Real estate | 2026 |
| MG157 Ltd | Transport & logistics | 2019 |
| MH Construction Solutions Ltd | Professional & scientific | 2019 |
| MH Global Holdings Ltd | Other services | 2023 |
| MH Web Group Investments Ltd | Real estate | 2021 |
| Mhdvs Ltd | Construction | 2013 |
| MHG Consultancy Ltd | Professional & scientific | 2023 |
| MIB Wealth Management Ltd | Professional & scientific | 2024 |
| MIC Investments Ltd | Financial services | 2019 |
| Michael Hosking Limited | Professional & scientific | 2023 |
| Michael Schmitt Ltd | Information & communication | 2020 |
| Michael T Ward Limited | Information & communication | 2019 |
| Michelle Garcia Ltd | Professional & scientific | 2013 |
| Michild Blackpool Limited | Health & social care | 2020 |
| Michild Midco Limited | Health & social care | 2019 |
| Michild Propco Limited | Real estate | 2019 |
| Mickleover Care Home Limited | Health & social care | 2024 |
| Micro-X UK Operations Limited | Manufacturing | 2021 |
| Midastone Ltd | Financial services | 2019 |
| Midland Sales Agencies Limited | Wholesale & retail | 2015 |
| Midsomerhousing Ltd | Real estate | 2022 |
| Midswed Properties Ltd | Real estate | 2024 |
| MIE Events Limited | Hospitality | 2023 |
| MIG International Limited | Administrative & support | 2003 |
| Mighty Titan Limited | Wholesale & retail | 2024 |
| Milanjo-Invest Ltd | Real estate | 2023 |
| Mili Invest Ltd | Real estate | 2016 |
| Milkshake Surrey Ltd | Other services | 2019 |
| Milky Monster Ltd | Wholesale & retail | 2023 |
| Millan Systems Limited | Administrative & support | 2024 |
| Milo&Kensi Limited | Wholesale & retail | 2025 |
| Milton Contracts Ltd | Administrative & support | 2022 |
| Milton Online Limited | Information & communication | 2019 |
| Milton Park Developments (Egham) Holdings Limited | Extraterritorial | 2007 |
| Milton Park Developments (Egham) Limited | Extraterritorial | 2005 |
| Mimosa Consultancy Ltd | Manufacturing | 2000 |
| Mind Body Safety Ltd. | Professional & scientific | 2022 |
| Mindset Films Ltd | Professional & scientific | 2023 |
| Mint Day Spa Ltd | Other services | 2012 |
| Mint Hairdressing Ltd | Other services | 2007 |
| Miparent Holdings Limited | Education | 2021 |
| Mirani Invest Ltd | Real estate | 2021 |
| Mirani Properties Ltd | Real estate | 2021 |
| Miricon Homes Ltd | Real estate | 2017 |
| Miricon Real Estate Ltd | Real estate | 2017 |
| Mithero Property Ltd | Real estate | 2021 |
| Miza Properties Ltd | Real estate | 2023 |
| MJ Motor Sales Ltd | Wholesale & retail | 2023 |
| MK Assets Management Ltd | Financial services | 2025 |
| MK Properties 1 Ltd | Real estate | 2023 |
| MKD Holdings Limited | Hospitality | 2020 |
| MKM Wealth Management Limited | Professional & scientific | 2019 |
| ML Global Travel Limited | Administrative & support | 2005 |
| MLK Trade Limited | Wholesale & retail | 2023 |
| Mmit Holding Ltd | Financial services | 2020 |
| Mmprf Ltd | Real estate | 2025 |
| MNT Property Investments Limited | Real estate | 2021 |
| Mogan Capital Ltd | Real estate | 2026 |
| Moira Meridian Holdings Ltd | Real estate | 2026 |
| Momax Properties Ltd | Real estate | 2023 |
| Monarch Keys Limited | Real estate | 2025 |
| Monetec Ltd | Professional & scientific | 2019 |
| Monsoon Homes Ltd | Real estate | 2017 |
| Montagna Properties Ltd | Real estate | 2024 |
| Montbleu Capital Ltd | Professional & scientific | 2023 |
| Montel Properties Ltd | Hospitality | 2019 |
| Montrose Property Management Ltd | Professional & scientific | 2002 |
| Monty Skincare Ltd | Other services | 2022 |
| Moonbeam Merchant Limited | Other services | 2024 |
| Moonfire Property Investment Ltd | Real estate | 2021 |
| Moonfire Property Trading Ltd | Hospitality | 2021 |
| Mordors Carpentry Limited | Construction | 2021 |
| Moretobricks Ltd | Real estate | 2022 |
| Morgon Properties Ltd | Real estate | 2023 |
| Mortgage Select Limited | Extraterritorial | 2015 |
| Mossocon Ltd | Professional & scientific | 2022 |
| Motor Check Limited | Extraterritorial | 2005 |
| Motoring Supply Company Limited | Wholesale & retail | 2002 |
| Movesecure Ltd | Professional & scientific | 2004 |
| Mphuk Limited | Real estate | 2018 |