| Metrosold Limited | Administrative & support | 1999 |
| Metroweigh Limited | Other services | 1978 |
| Mets Investments Limited | Real estate | 2025 |
| Metspec Global Limited | Financial services | 2020 |
| Meyer Property Limited | Real estate | 2017 |
| MGB Learning Centre Ltd | Education | 2013 |
| MGF Estates Limited | Real estate | 2022 |
| MGI Limited | Construction | 2020 |
| MGM International Ltd | Arts & recreation | 2018 |
| MGS Holdings Limited | Professional & scientific | 2015 |
| MGW Construction Limited | Construction | 2011 |
| MGW Investments Limited | Real estate | 2023 |
| Mhmhmp Properties Ltd | Real estate | 2026 |
| MIA Property Construction Ltd | Construction | 2022 |
| Michael Dobias (Shared Services) Limited | Professional & scientific | 2011 |
| Michael Levy Properties Limited | Real estate | 1987 |
| Michaelson JAY Ltd | Professional & scientific | 2025 |
| Micro-Ecologic Limited | Professional & scientific | 2019 |
| Microlife Sciences Limited | Extraterritorial | 2024 |
| Middle Stump Limited | Professional & scientific | 2023 |
| Midway Builders Ltd | Construction | 2019 |
| Migrant Integration UK | Professional & scientific | 2025 |
| Mihail & Victor Construction Limited | Construction | 2018 |
| Mila Business Consultancy Ltd | Wholesale & retail | 2020 |
| Mild Properties Ltd | Real estate | 2015 |
| Mild Spirits Ltd | Wholesale & retail | 2022 |
| Miliora Limited | Wholesale & retail | 2023 |
| Mill Link Developments Limited | Administrative & support | 2008 |
| Millbrook Freehold Limited | Households | 2018 |
| Millennium Court (NO. 1) Limited | Households | 1997 |
| Millennium Court (NO.2) Limited | Households | 1997 |
| Millennium Court (NO.4) Limited | Real estate | 1999 |
| Millennium International College Ltd | Education | 2023 |
| Miller Electrical & Lighting Services Ltd | Construction | 2021 |
| Millfields Joint Estate Management Company Limited | Households | 2002 |
| Millfields Residents Management Company Limited | Households | 2002 |
| Millharbour Developments Limited | Real estate | 2005 |
| Millroys Consulting Ltd | Construction | 2026 |
| Milone Consulting Ltd | Information & communication | 2017 |
| Milton Executive Cars Limited | Transport & logistics | 2008 |
| Milton Investments Limited | Administrative & support | 1999 |
| Mime Carpet Cleaning Ltd | Administrative & support | 2024 |
| Mimiru Ltd | Professional & scientific | 2025 |
| Mind and Souls Connection Limited | Health & social care | 2024 |
| Mind-Worm Limited | Information & communication | 2011 |
| Mindful Construction Ltd | Administrative & support | 2016 |
| Mindfully Made Ltd | Arts & recreation | 2024 |
| Mindset Universe Media Ltd | Wholesale & retail | 2025 |
| Miniature Broadcast Cameras Ltd | Manufacturing | 2006 |
| Mint Electrical Limited | Construction | 2023 |
| Mintel Property Limited | Real estate | 2022 |
| Mira Homes Limited | Real estate | 2023 |
| Miriad Property Holdings Limited | Financial services | 2022 |
| Miriad Property Investments Limited | Real estate | 2016 |
| Mirimbm Limited | Construction | 2021 |
| Misa Ventures Limited | Wholesale & retail | 2021 |
| Misentinel Limited | Information & communication | 2021 |
| Misp Construction Ltd | Construction | 2019 |
| Mistral Agencies Limited | Professional & scientific | 2020 |
| Mitan Ltd | Construction | 2026 |
| Mitchell & Alexander Limited | Construction | 2012 |
| Mitrev Ltd | Construction | 2022 |
| MIV Electrical Services Ltd | Construction | 2016 |
| MIX & Muddle Limited | Hospitality | 2023 |
| MJ Square Ltd | Real estate | 2024 |
| Mjaf Investments Ltd | Real estate | 2025 |
| Mjpc Fitness Ltd | Arts & recreation | 2018 |
| MJR Homes Limited | Real estate | 2021 |
| MJR Lettings Limited | Real estate | 2021 |
| MJS Fire Ltd | Public administration | 2025 |
| MJT Property Ltd | Real estate | 2017 |
| MKB Renovations Ltd | Construction | 2021 |
| Mkbv Developments Limited | Real estate | 2025 |
| Mkbv Holdings Limited | Financial services | 2025 |
| Mkbv Investments Limited | Financial services | 2025 |
| Mkbv Property Limited | Financial services | 2025 |
| MKH Builders Limited | Construction | 1998 |
| MKR Social Limited | Professional & scientific | 2018 |
| MKX Engineering Limited | Administrative & support | 2014 |
| Mlgas Epping Ltd | Construction | 2017 |
| MLS Maintenance Ltd | Construction | 2016 |
| Mmfdi Ltd | Public administration | 2025 |
| MMJ Investments Holding Ltd | Real estate | 2020 |
| MMS Interiors Ltd | Construction | 2024 |
| Moatville LLP | | 2021 |
| Mobile Store Europe Ltd | Wholesale & retail | 2016 |
| Modena Construction Limited | Construction | 2020 |
| Modern Klassics Ltd | Wholesale & retail | 2023 |
| Modern Paper Technology Limited | Wholesale & retail | 2010 |
| Modern Woman Limited | Information & communication | 2017 |
| Modern Woman Online Limited | Other services | 2023 |
| Modoco Services Ltd | Information & communication | 2021 |
| Mofl Ltd | Construction | 2020 |
| Mojito Events Limited | Other services | 2014 |
| Mokel Management Limited | Real estate | 1968 |
| MOL Chemical Tankers Europe Limited | Transport & logistics | 2001 |
| Moloney Engineering Limited | Professional & scientific | 2024 |
| Monahan Solutions Limited | Public administration | 2023 |
| Monarca Commodities Limited | Administrative & support | 2024 |
| Monarch Asset Management Limited | Other services | 2013 |