| Mentor Tech Ltd | Information & communication | 2024 |
| Meowve Franchise Ltd | Professional & scientific | 2022 |
| Mepex BIM Limited | Information & communication | 2015 |
| Mera Jewellery Ltd | Wholesale & retail | 2025 |
| Meraki Software Ltd | Information & communication | 2022 |
| Merasa Damai Wellness Limited | Professional & scientific | 2025 |
| Mercatus Associates Limited | Professional & scientific | 2021 |
| Mercer Street Marketing and Consulting Limited | Professional & scientific | 2002 |
| Merchant's Quay Limited | Real estate | 2003 |
| Merchants Tavern 2026 Ltd | Hospitality | 2026 |
| Mercian Initiatives Limited | Wholesale & retail | 1990 |
| Mercurian Solutions Limited | Professional & scientific | 2012 |
| Mercury Strategic Limited | Professional & scientific | 2025 |
| Meri Dilli Glasgow Limited | Hospitality | 2026 |
| Meri Dilli Limited | Hospitality | 2025 |
| Meridian Admin Services Ltd | Administrative & support | 2025 |
| Merit Group Services Limited | Financial services | 2017 |
| Merit Health Limited | Manufacturing | 2020 |
| Merit Holdings Limited | Manufacturing | 2002 |
| Merjaan Ltd | Wholesale & retail | 2025 |
| Merlin Surgical Holdings Limited | Health & social care | 2019 |
| Meroë Consulting Ltd | Health & social care | 2021 |
| Merrilees Property Ltd | Real estate | 2025 |
| Merrychef Limited | Financial services | 1992 |
| Merton Management Company Limited | Households | 1988 |
| Merus IT Services Ltd. | Information & communication | 2014 |
| Meryem Carson Ltd | Arts & recreation | 2022 |
| Mesma Limited | Information & communication | 2011 |
| Mesmerising Beauty Ltd | Other services | 2025 |
| Mespar Limited | Information & communication | 2023 |
| MET Recruitment UK Group Ltd | Financial services | 2022 |
| Meta Consulting (UK) Limited | Administrative & support | 2004 |
| Meta Maintenance Limited | Construction | 2023 |
| Metafirm Ltd | Health & social care | 2022 |
| Metcalf Property Consultancy Limited | Real estate | 2009 |
| Metcalfe Components Limited | Professional & scientific | 2019 |
| Method Building Consultancy (Newcastle) Limited | Administrative & support | 2021 |
| Method Building Consultancy Limited | Administrative & support | 2020 |
| Metis Barber Ltd | Other services | 2021 |
| Metnor Construction Limited | Construction | 2002 |
| Metnor Quays Limited | Construction | 2006 |
| Metrik Group Ltd | Professional & scientific | 2021 |
| Metrisk Promotional Management Limited | Professional & scientific | 2019 |
| Metrix FGG Ltd | Financial services | 2023 |
| Metrix NDT Limited | Manufacturing | 2013 |
| Metro Autopark Limited | Administrative & support | 2014 |
| Metro Imaging Limited | Professional & scientific | 1986 |
| Metro Imaging Ventures Limited | Professional & scientific | 2011 |
| Metro Inns Ltd | Hospitality | 2025 |
| Metro Mortgages Limited | Financial services | 2010 |
| Metro MOT NE Ltd | Wholesale & retail | 2017 |
| Metro Repro Limited | Manufacturing | 1992 |
| Metrobus Limited | Professional & scientific | 1983 |
| Metrofleet Ltd | Wholesale & retail | 2025 |
| Metropolitan Association of Cost Accountants Limited(The) | Other services | 1943 |
| Metropolitan Industrial Park Limited | Households | 2022 |
| Metropolitan Residents Management Company Limited | Real estate | 2016 |
| Metrovets Limited | Professional & scientific | 2010 |
| Mexar Limited | Manufacturing | 2007 |
| Meyers Franchising Limited | Real estate | 2017 |
| Meyler and Tarr Limited | Households | 2023 |
| Mezza Luna Ltd | Hospitality | 2024 |
| MF Commercial Properties Ltd | Real estate | 2018 |
| MF LP | | 2024 |
| MF Residential Ltd | Real estate | 2020 |
| MFB Innovations Limited | Professional & scientific | 2018 |
| MFF EYE Services Limited | Health & social care | 2023 |
| MFK Barber Ltd | Other services | 2022 |
| MFV ST Cuthbert Boats Limited | Transport & logistics | 2014 |
| MG Grand Designs Ltd | Professional & scientific | 2020 |
| MGA (Golf) Ltd | Wholesale & retail | 2024 |
| MGA Traders Limited | Wholesale & retail | 2020 |
| MGP Fitness Ltd | Arts & recreation | 2026 |
| MGR Access & Coatings Ltd | Construction | 2019 |
| MGR NE Limited | Wholesale & retail | 2022 |
| Mgranger IT Solutions Limited | Information & communication | 2018 |
| MGS Investment Properties Limited | Real estate | 2017 |
| MGT Building and Renovation Limited | Construction | 2023 |
| MGW Clinical Communications Ltd | Professional & scientific | 2026 |
| MH Construction Safety Services Ltd | Construction | 2025 |
| MH Electrical Contractors NE Ltd | Manufacturing | 2020 |
| MH Enterprises (North) Limited | Extraterritorial | 2011 |
| MH Holdings (North) Limited | Professional & scientific | 2011 |
| MH Research & Design Ltd | Professional & scientific | 2012 |
| MH Self Defence System Ltd | Health & social care | 2019 |
| MH1 Holdco Limited | Other services | 2015 |
| MHE-360 Ltd | Manufacturing | 2024 |
| Mhfs Services Ltd | Professional & scientific | 2024 |
| MHH Ventures Ltd | Wholesale & retail | 2026 |
| MHL Building Services (M&E) Limited | Construction | 2010 |
| Mhmak Corporation Ltd | Wholesale & retail | 2021 |
| Mhmrd Ltd | Health & social care | 2025 |
| Mhpi Limited | Real estate | 2011 |
| MHS Site Solutions Ltd | Construction | 2022 |
| MHS Strategic Consulting Ltd | Real estate | 2018 |
| Mi-Say Limited | Administrative & support | 2017 |
| Miafal Limited | Households | 2020 |
| Miah Auto Services Limited | Wholesale & retail | 2025 |
| Miah Corporation Ltd | Financial services | 2023 |
| Miah Corporation Properties Ltd | Real estate | 2023 |