| MTA Santos Ltd | Financial services | 2025 |
| MTM Sports Coaching and Mentoring Ltd | Arts & recreation | 2025 |
| Mubashira Investments Limited | Real estate | 2022 |
| Muddy Boots Forest School Ltd | Arts & recreation | 2016 |
| Muehlhan Wind Service UK Limited | Administrative & support | 2019 |
| Muge Design Limited | Wholesale & retail | 2017 |
| Muhunthan Ltd | Financial services | 2025 |
| Mullar Surveying Limited | Construction | 2019 |
| Multi Kitchen MK Ltd | Hospitality | 2025 |
| MULTIPLE7 Ltd | Health & social care | 2026 |
| Mummy Yahya Limited | Professional & scientific | 2023 |
| Munchicken Ltd | Hospitality | 2026 |
| Mundell Services Limited | Administrative & support | 2016 |
| Munyard House RTM Company Limited | Households | 2025 |
| Murch Consulting Limited | Financial services | 2014 |
| Murph Construction Ltd | Construction | 2022 |
| Murray Fraser Group Limited | Financial services | 2013 |
| Muscle Art Nutrition Ltd | Arts & recreation | 2018 |
| Music & Media Hub UK Limited | Information & communication | 2019 |
| Musicando Ltd | Information & communication | 2020 |
| Mustang Fashions Limited | Professional & scientific | 1979 |
| Mustard Sandwich Shop Ltd | Health & social care | 2026 |
| Muster Limited | Manufacturing | 2007 |
| Mutineers Brewery Limited | Manufacturing | 2019 |
| Mutley Grill Limited | Hospitality | 2019 |
| Mutualphase Property Management Limited | Households | 1993 |
| Muzox Limited | Households | 2020 |
| Muzuro Investment Ltd | Real estate | 2025 |
| Muzuro Properties Ltd | Construction | 2017 |
| MV Properties (Downe) Limited | Households | 2020 |
| Mvautomotive Limited | Wholesale & retail | 2020 |
| MVP Advisory Ltd | Professional & scientific | 2025 |
| MVW Fitness Limited | Professional & scientific | 2026 |
| MW DRY Cleaners Ltd | Other services | 2026 |
| Mwimageworks Ltd | Professional & scientific | 2019 |
| My Favourist Ltd | Hospitality | 2012 |
| My FUN Photobooth Limited | Professional & scientific | 2026 |
| My Home Sales and Letting Ltd | Real estate | 2019 |
| My Kids Agency Ltd | Administrative & support | 2017 |
| My Pure World Limited | Wholesale & retail | 2026 |
| My Tutor Quest Ltd | Education | 2025 |
| My UK Services Ltd | Real estate | 2021 |
| Myatt Corporation Ltd | Financial services | 2020 |
| MYC Drylining Ltd | Construction | 2018 |
| Mycomfortstay Ltd | Hospitality | 2025 |
| Mydproperties Limited | Real estate | 2018 |
| Myla Health Limited | Health & social care | 2021 |
| MYLASKYE07 Ltd | Professional & scientific | 2023 |
| Mynd Body Ltd | Health & social care | 2020 |
| Myrtle and Forrester Associates Limited | Real estate | 2024 |
| Mysports.Social Limited | Professional & scientific | 2017 |
| Mystillium Designs Ltd | Manufacturing | 2024 |
| MZJ Glazing Ltd | Construction | 2023 |
| Máximos Históricos Ltd. | Education | 2016 |
| N & W Enterprises Limited | Real estate | 2024 |
| N Bhardwaj Ltd | Health & social care | 2022 |
| N I Strategy Limited | Administrative & support | 2017 |
| N Labis Ltd | Health & social care | 2026 |
| N London Property Refurbishments Ltd | Construction | 2016 |
| N S Sheet Metal Limited | Manufacturing | 2017 |
| N V Accounting LLP | | 2012 |
| N&M Insulation Ltd | Construction | 2024 |
| N1 First Ltd | Information & communication | 2019 |
| N2N Holding Limited | Financial services | 2023 |
| N2N Investments Limited | Financial services | 2026 |
| N2N IT Limited | Information & communication | 2023 |
| NA Clothing Ltd | Wholesale & retail | 2018 |
| NA London Ltd | Wholesale & retail | 2024 |
| NA Stratford Ltd | Wholesale & retail | 2021 |
| NAB Properties Limited | Real estate | 1998 |
| Naff Art Ltd | Wholesale & retail | 2024 |
| Nagashree Ltd | Manufacturing | 2011 |
| Nahla Healthcare Limited | Administrative & support | 2013 |
| Nailed IT Bromley Limited | Other services | 2019 |
| Nails & Spa (Caterham) Limited | Other services | 2017 |
| Nails Time Limited | Other services | 2023 |
| Nailtini NO 5 Ltd | Other services | 2016 |
| Nana Holdings Limited | Financial services | 2022 |
| Napier Court (Grove Park) Management Limited | Households | 1997 |
| Nardo 1 Limited | Extraterritorial | 2024 |
| Narsons Ltd | Other services | 2023 |
| Narube Ltd | Manufacturing | 2025 |
| Nash Mills Wharf RTM Company Limited | Households | 2023 |
| Nassou Limited | Arts & recreation | 2009 |
| Natalie Gill Ltd | Wholesale & retail | 2019 |
| Nathan Fast Food Ltd | Hospitality | 2019 |
| Nathan Superstore Limited | Wholesale & retail | 2023 |
| National Building Consultants Ltd | Professional & scientific | 2026 |
| National Cleaning Solutions Limited | Administrative & support | 2026 |
| National Electrotechnical Training Organisation | Education | 1997 |
| National Investments (S E) Ltd | Financial services | 2008 |
| Natlyssa Limited | Financial services | 2018 |
| Natura Capital Limited | Professional & scientific | 2024 |
| Natural Oils Ltd | Wholesale & retail | 2025 |
| Natures Aroma Limited | Public administration | 2022 |
| Natures Nest World Ltd | Wholesale & retail | 2025 |
| Navah Grace Consulting Ltd | Administrative & support | 2021 |
| Naxell Holdings Limited | Financial services | 2015 |
| Nayela Travel Ltd | Extraterritorial | 2024 |
| Naysell Holdings Limited | Real estate | 2015 |