| Mdjg Ltd | Real estate | 2021 |
| Mdmrr Limited | Health & social care | 2023 |
| Meadow Court Management Limited | Households | 1961 |
| Measured Protection Limited | Professional & scientific | 1991 |
| Medli Health Holding Limited | Financial services | 2022 |
| Medli Health Limited | Information & communication | 2022 |
| Medusa Vape 1 Ltd | Wholesale & retail | 2023 |
| Meeru Studios Ltd | Real estate | 2023 |
| Meica Engineering Solutions Ltd | Other services | 2015 |
| Merintech Limited | Information & communication | 2023 |
| Metabet Limited | Arts & recreation | 2019 |
| Metal Fabrication & Design Ltd | Professional & scientific | 2024 |
| Metanoia Nexus Group Ltd | Professional & scientific | 2017 |
| Metric Associates Limited | Professional & scientific | 2015 |
| Metta Controls Limited | Professional & scientific | 2025 |
| Meudon House (Farnborough) Residents Management Company Limited | Households | 2016 |
| Mevyn Limited | Information & communication | 2013 |
| Mezzo Foods Ltd | Hospitality | 2026 |
| MFC I.T. Solutions Limited | Professional & scientific | 2015 |
| MFM Consulting Ltd | Information & communication | 2017 |
| MG2023 Ltd | Professional & scientific | 2023 |
| Mgbooth Ltd | Construction | 2023 |
| Mggm Aviation Ltd | Manufacturing | 2022 |
| MGR Business Limited | Other services | 2024 |
| MGY Rentals Ltd | Real estate | 2025 |
| Mhhfood Ltd | Extraterritorial | 2022 |
| MIC Drop Events UK Ltd | Administrative & support | 2026 |
| Mike Roberts Financial Services Limited | Financial services | 2005 |
| Milestone Transport Planning Limited | Transport & logistics | 2004 |
| Miller Place (H84) Management Company Limited | Households | 2007 |
| Minacare Limited | Health & social care | 2022 |
| Minelli Care Ltd | Administrative & support | 2024 |
| Mini-Blu Ltd | Wholesale & retail | 2022 |
| Mini-San Ltd | Wholesale & retail | 2024 |
| Mini-Too Ltd | Wholesale & retail | 2023 |
| Mirrored Ltd | Wholesale & retail | 2019 |
| Miss Maker Ltd | Education | 2011 |
| Mitcham Electrician Ltd | Construction | 2021 |
| Mitchellwheeler Limited | Construction | 2016 |
| Mithorne Solutions Ltd | Professional & scientific | 2025 |
| Miura Risk Management Limited Liability Partnership | | 2019 |
| MJ Group 1 Ltd | Construction | 2025 |
| MJA Utilities Ltd | Construction | 2018 |
| MJB Payroll Services Limited | Professional & scientific | 2012 |
| Mjis Investments Limited | Wholesale & retail | 2026 |
| MJK Consulting Limited | Financial services | 2022 |
| MK Fleet Taxi Ltd | Transport & logistics | 2024 |
| Mkott Construction Ltd | Construction | 2022 |
| MM Marketing Services Ltd | Information & communication | 2016 |
| MM11SPORTS Limited | Wholesale & retail | 2024 |
| Mmoore Limited | Financial services | 2026 |
| Mncs U.K Ltd | Administrative & support | 2023 |
| Mocha Brows Ltd | Other services | 2022 |
| Modder Place Limited | Real estate | 2007 |
| Modular Projects Limited | Construction | 2020 |
| Modvet Limited | Hospitality | 1989 |
| Monjii Ltd | Wholesale & retail | 2021 |
| Montmine Ltd | Administrative & support | 2003 |
| Monvilla Limited | Administrative & support | 2016 |
| Moogram House Limited | Real estate | 2022 |
| Moonwalk Flooring Ltd | Construction | 2020 |
| Morgan Made Ltd. | Construction | 2019 |
| Moroka Group Ltd | Administrative & support | 2015 |
| Mortgage & Investment Choices Limited | Financial services | 2010 |
| Mortlock Painting and Decoratring Limited | Construction | 2025 |
| Mozambik Retail UK Ltd | Wholesale & retail | 2026 |
| MPP Investment Limited | Real estate | 2021 |
| MR MC Bater Ltd | Health & social care | 2018 |
| MR13 Limited | Extraterritorial | 2024 |
| MRS Systems Limited | Information & communication | 2022 |
| MRS Web Solutions Limited | Information & communication | 1999 |
| MSV Project Services Limited | Professional & scientific | 2023 |
| MTR Fight Wear Limited | Wholesale & retail | 2024 |
| Mumentum HQ Limited | Administrative & support | 2024 |
| Mummy Barrow Limited | Information & communication | 2014 |
| Mummy Day Clean Ltd | Administrative & support | 2019 |
| Murmurate Ltd | Construction | 2019 |
| Murray and Priory Ltd. | Extraterritorial | 2013 |
| Musicians Hearing Services (UK) Limited | Extraterritorial | 2018 |
| Mustard Brickwork U.K. Ltd | Construction | 2023 |
| Muzets Private Limited | Other services | 2020 |
| MW Service and Repair Ltd | Wholesale & retail | 2026 |
| MWA Homes Limited | Construction | 2016 |
| My Everliving Ltd | Manufacturing | 2025 |
| My Firms App Limited | Information & communication | 2014 |
| My Marketing Dept Ltd | Professional & scientific | 2020 |
| My Megam Ltd | Real estate | 2024 |
| My PAI Ltd | Information & communication | 2025 |
| N J Williams Accountants Limited | Professional & scientific | 2002 |
| N W Read & Co Limited | Real estate | 2012 |
| NAC Care Services Limited | Health & social care | 2017 |
| Nacu Valeting Limited | Wholesale & retail | 2023 |
| Nakoma UK Limited | Wholesale & retail | 2018 |
| Nalla Consulting Ltd | Construction | 2018 |
| Naranja UK Holdings Limited | Arts & recreation | 2024 |
| NAT Talks Ltd | Education | 2020 |
| NAT Talks Media Ltd | Information & communication | 2020 |
| Natco Consulting Ltd | Professional & scientific | 2025 |
| National Home Maintenance Ltd | Construction | 2023 |
| Natthiko Ltd | Information & communication | 2023 |