| M & R Property Services Limited | Real estate | 2019 |
| M & S Drapes Limited | Administrative & support | 2015 |
| M & Sons (London) Ltd | Construction | 2021 |
| M & Y Autos Ltd | Wholesale & retail | 2019 |
| M a Medical Services Ltd | Health & social care | 2004 |
| M Civils Ltd | Construction | 2021 |
| M Fernandes Limited | Wholesale & retail | 2022 |
| M G (UK) Corporation Limited | Information & communication | 2012 |
| M Imaging Ltd | Professional & scientific | 2025 |
| M Juma Ltd | Health & social care | 2017 |
| M K D Consultancy Ltd | Professional & scientific | 2023 |
| M K Foods & Wine Ltd | Wholesale & retail | 2023 |
| M K M & Trading Ltd | Wholesale & retail | 2022 |
| M K Security London Ltd | Wholesale & retail | 2022 |
| M One Motors Ltd | Wholesale & retail | 2022 |
| M P Hones IT Services Ltd | Information & communication | 2014 |
| M R H Real Estate Limited | Hospitality | 2007 |
| M S Loans Ltd | Financial services | 2002 |
| M Sheehan Ltd. | Professional & scientific | 2023 |
| M&A Accounting Ltd | Professional & scientific | 2019 |
| M&B Property & Investment Company Limited | Real estate | 2015 |
| M&D Renovations Ltd | Construction | 2021 |
| M&E Real Estates Ltd | Real estate | 2014 |
| M&I Decorators Ltd | Construction | 2021 |
| M&I Mechanical Ltd | Construction | 2024 |
| M&M Building and Construction Limited | Construction | 2019 |
| M&M Car Collective Limited | Wholesale & retail | 2026 |
| M&M Enterprise Wembley Ltd | Wholesale & retail | 2023 |
| M&M Multinational Ltd | Wholesale & retail | 2025 |
| M&M Prestige Decorators Ltd | Construction | 2024 |
| M&M Ursu Construction & Engineering Limited | Construction | 2025 |
| M. N. Coachworks Limited | Wholesale & retail | 2008 |
| M.A Commercial & Fitting Ltd | Construction | 2023 |
| M.E.N.S. Trading Company Limited | Wholesale & retail | 1982 |
| M.R.S Fast Food Limited | Hospitality | 2020 |
| M.S. Lighting Ltd | Construction | 2011 |
| M2 (UK) Limited | Health & social care | 2013 |
| M3 Maintenance Ltd | Construction | 2026 |
| M3 Technology Ltd | Wholesale & retail | 2022 |
| MAA Ambe Limited | Wholesale & retail | 2025 |
| Maapaa's Kitchen Ltd | Wholesale & retail | 2024 |
| MAB Housing Limited | Real estate | 2025 |
| MAC Landscaping Limited | Administrative & support | 2019 |
| MAC Music Productions Ltd | Arts & recreation | 2024 |
| MAC Repairs Specialist Limited | Other services | 2026 |
| Macbrit Solutions Limited | Education | 2016 |
| Macgill UK Limited | Administrative & support | 2020 |
| Machine Made Rugs Limited | Manufacturing | 2018 |
| Maclu Limited | Education | 2011 |
| Macs Caterers Limited | Hospitality | 2013 |
| Macte International Ltd | Wholesale & retail | 2022 |
| MAD Vacations Limited | Administrative & support | 2026 |
| Madad | Health & social care | 2009 |
| Madalin Consultancy Ltd | Wholesale & retail | 2019 |
| Made by Ummi Ltd | Wholesale & retail | 2017 |
| Madhaparia Property Investments Ltd | Real estate | 2018 |
| Madhav Traders Limited | Hospitality | 2026 |
| Madinah Trading Limited | Wholesale & retail | 2024 |
| MAE Medical Aesthetics Limited | Health & social care | 2025 |
| Maeme's Burntoak Ltd | Hospitality | 2022 |
| Maemuki Ltd | Wholesale & retail | 2020 |
| Maestro Collects Ltd | Wholesale & retail | 2026 |
| Mafhh Imagination Limited | Information & communication | 2024 |
| Mafiabusiness Ltd | Other services | 2016 |
| Maftean Construction Ltd | Construction | 2019 |
| MAG & LEE Trading Limited | Hospitality | 2024 |
| Magarajothi Enterprises Ltd | Manufacturing | 2025 |
| Magic Park Limited | Real estate | 2024 |
| Magic Training Ltd | Education | 2015 |
| Magical Export Limited | Manufacturing | 2026 |
| Magical Moments Day Nursery Limited | Education | 2023 |
| Magicspoon Ltd | Administrative & support | 2016 |
| Magnate Holdings Ltd | Financial services | 2023 |
| Magnetic Media Academy C.I.C. | Manufacturing | 2025 |
| Magnificent London Ltd | Construction | 2024 |
| Magnificent Molars Ltd | Health & social care | 2022 |
| Magnopus Consultancy (UK) Ltd | Construction | 2020 |
| Magnum Health Care Services Limited | Health & social care | 2019 |
| Magnum Trading Investments Limited | Real estate | 2026 |
| Mags Intelligence Ltd | Wholesale & retail | 2026 |
| MAH Hadian Dental Studio Ltd | Health & social care | 2026 |
| Mah-Cad Limited | Construction | 2012 |
| Maha Jewellers Ltd | Wholesale & retail | 2016 |
| Mahaaveer Ltd | Financial services | 2026 |
| Mahadex Ltd | Information & communication | 2025 |
| Mahalaxmi Trading Limited | Hospitality | 2020 |
| Mahamari Amman Ltd | Health & social care | 2015 |
| Mahant Suppliers Ltd | Wholesale & retail | 2025 |
| Maharaj Logistics Ltd | Transport & logistics | 2025 |
| Maharani Limited | Information & communication | 2018 |
| Mahdi and Omar Properties Limited | Real estate | 2022 |
| Mahdiy Properties Ltd | Real estate | 2020 |
| Maheshwari Bhawan UK | Other services | 2021 |
| Mahfields 2 Ltd | Real estate | 2022 |
| Mahfields Ltd | Real estate | 2017 |
| Mahi Holdings Limited | Real estate | 2025 |
| Mahi Property Services Limited | Real estate | 2024 |
| Mahika Limited | Administrative & support | 2015 |
| MAI Collection Ltd | Wholesale & retail | 2024 |
| MAI Design Limited | Wholesale & retail | 2015 |