| Mini's Fitness & Nutrition Ltd | Other services | 2025 |
| Minigolf Limited | Arts & recreation | 2007 |
| Minori Partnerships Limited | Professional & scientific | 2026 |
| Mint Formations Ltd | Administrative & support | 2017 |
| Mintplus Investments Ltd | Real estate | 2021 |
| Mintplus Services Ltd | Professional & scientific | 2018 |
| Mirac Entertainment Ltd | Information & communication | 2025 |
| Miraglia Enterprise Group Ltd | Financial services | 2020 |
| Mirilux Ltd | Health & social care | 2024 |
| Misho IT Firm Ltd | Information & communication | 2023 |
| Misorella Ltd | Wholesale & retail | 2026 |
| Mistry Player Limited | Professional & scientific | 2010 |
| Mitcham Enterprises Ltd | Construction | 2022 |
| Mitchells Trading Limited | Administrative & support | 2024 |
| Mizz Wizz Ltd | Professional & scientific | 2024 |
| MJ Data Solutions Ltd | Information & communication | 2017 |
| MJ Fernandes Homes Ltd | Real estate | 2023 |
| MJ Fernandes Ltd | Wholesale & retail | 2020 |
| MJ Holdings (Ruislip) Limited | Financial services | 2022 |
| MJ Minibuses Limited | Transport & logistics | 2023 |
| MJ Properties (Ruislip) Limited | Real estate | 2022 |
| MJ Smiles Ltd | Health & social care | 2017 |
| MJ Wellness & Training London Ltd | Wholesale & retail | 2025 |
| MJF Electrical Solutions Limited | Construction | 2022 |
| MJL Toilet & Welfare Hire Limited | Administrative & support | 2024 |
| MJM Acquisitions Limited | Financial services | 2017 |
| MJM Cars and Commercials Limited | Wholesale & retail | 2021 |
| MK Building Contractors 25 Ltd | Construction | 2020 |
| MK Leasing Services Limited | Real estate | 2025 |
| Mk&R Electrical Services Ltd | Energy | 2017 |
| MK1 Trade Co Ltd | Wholesale & retail | 2021 |
| MKA Smart Trading Ltd | Hospitality | 2020 |
| Mkay & Co Ltd | Professional & scientific | 2023 |
| MKB Motors Ltd | Wholesale & retail | 2018 |
| Mkdynamax Limited | Transport & logistics | 2024 |
| Mkmit Limited | Information & communication | 2025 |
| ML Risk Management Limited | Financial services | 2023 |
| MLM Removals & Storage Limited | Transport & logistics | 2017 |
| MM Design & Build Limited | Construction | 2015 |
| Mmaca Ltd | Information & communication | 2018 |
| MMC Decorators Limited | Construction | 2024 |
| MMI Trading & Sons Limited | Administrative & support | 2024 |
| Mmmj Consulting and Training Ltd | Professional & scientific | 2019 |
| MMQ Piano at Home Ltd | Education | 2020 |
| MMW Academy Ltd | Wholesale & retail | 2026 |
| Mmxvii Ltd | Real estate | 2017 |
| MNS Financial Services Limited | Professional & scientific | 2016 |
| MNT Trading Ltd | Wholesale & retail | 2026 |
| Mo&Misty Ltd | Wholesale & retail | 2024 |
| Mobile Tyre Xpert Ltd | Wholesale & retail | 2026 |
| Mobility Bathrooms Limited | Wholesale & retail | 2001 |
| Mocha Management Ltd | Households | 2023 |
| Mocha One Investments Ltd | Real estate | 2022 |
| Model Home Developments Limited | Construction | 2025 |
| Model Properties Ltd | Real estate | 2013 |
| Modenhaus Ltd | Wholesale & retail | 2026 |
| Modestar Limited | Wholesale & retail | 2017 |
| Modim Limited | Hospitality | 2012 |
| Module Construction Ltd | Administrative & support | 2024 |
| Modycorp Limited | Information & communication | 2026 |
| Mohamedali Investments Ltd | Other services | 2011 |
| Mojofoto Ltd | Professional & scientific | 2010 |
| Mokades Limited | Administrative & support | 2023 |
| Mold BEE Construction Ltd | Construction | 2018 |
| Molesey Averna Ltd | Hospitality | 2026 |
| Molka Global Ltd | Wholesale & retail | 2025 |
| Momentum Advisory Ltd | Professional & scientific | 2019 |
| Momentum Sports Management Limited | Arts & recreation | 2017 |
| Momi Properties Development Ltd | Real estate | 2026 |
| Momos Fried Chicken Limited | Hospitality | 2025 |
| MON Adams Ltd | Other services | 2020 |
| Monarch Gardens Perfume Ltd | Manufacturing | 2022 |
| Mondo Berry Limited | Wholesale & retail | 2004 |
| Moneysprite Capital Ltd | Financial services | 2025 |
| Monovia Ltd | Professional & scientific | 2025 |
| Montana Wyndham Limited | Professional & scientific | 2004 |
| Monte Rosa Holidays Limited | Administrative & support | 2004 |
| Monty Baines & Co Limited | Financial services | 2025 |
| Moody Bros Limited | Construction | 2005 |
| Moonlight Ltd | Administrative & support | 2006 |
| Moonliight Ltd | Real estate | 2024 |
| Moonplague Productions Limited | Extraterritorial | 1990 |
| Moore and Associates Consultancy Limited | Professional & scientific | 2024 |
| Moore Global Solutions Limited | Wholesale & retail | 2022 |
| Moorketing Ltd | Administrative & support | 2015 |
| MOP N Go Ltd | Administrative & support | 2025 |
| More Than Mountains Ltd | Professional & scientific | 2020 |
| Morex Group Ltd | Financial services | 2024 |
| Morgan Productions Limited | Construction | 2024 |
| Morgan’S Lifting Services Limited | Construction | 2018 |
| Mortgage Class Limited | Professional & scientific | 2007 |
| Mortgage Lending Solutions Ltd | Financial services | 2019 |
| Mosaic Urban Design Limited | Professional & scientific | 2010 |
| Moshwide Security Solutions Ltd | Other services | 2019 |
| Mossdyp Limited | Hospitality | 1981 |
| Mother’S House Ltd | Real estate | 2024 |
| MOTIV8 Sports and Fitness Ltd | Arts & recreation | 2013 |
| Motivate ME Coaching Ltd | Administrative & support | 2022 |
| Motormove Bodyworks Ltd | Wholesale & retail | 2025 |
| Motormove Logistics Ltd | Transport & logistics | 2025 |