| Mogok Gems UK Limited | Wholesale & retail | 2022 |
| Mojana IT Services Ltd | Information & communication | 2018 |
| Molecular Search Ltd | Administrative & support | 2021 |
| Molly-Meg Limited | Wholesale & retail | 2009 |
| Momentum Finance Ltd | Real estate | 2025 |
| Mona HAN Business Services Limited | Professional & scientific | 2009 |
| Money JAM Limited | Information & communication | 2016 |
| Money MOB Ltd | Administrative & support | 2017 |
| Monk Property Partnership LLP | | 2022 |
| Monsenlove Ltd | Information & communication | 2024 |
| Montagu Page Ltd | Professional & scientific | 2022 |
| Mooi-H Ltd | Wholesale & retail | 2018 |
| Moon Zone Ltd | Wholesale & retail | 2024 |
| Morris a Ltd | Health & social care | 2025 |
| Morton Gardens Limited | Health & social care | 2017 |
| Moshpit Ltd | Wholesale & retail | 2020 |
| Mosuraz Limited | Real estate | 2019 |
| Motion Junkies Limited | Wholesale & retail | 2010 |
| Moud Aesthetics Ltd | Arts & recreation | 2025 |
| Moustache Barber London Ltd | Other services | 2026 |
| Movement Scaffolding Ltd | Construction | 2024 |
| Moyna Talcer Limited | Health & social care | 2019 |
| MP43 Retail Ltd | Wholesale & retail | 2025 |
| MPG Holdings Ltd | Arts & recreation | 2025 |
| MRM Oxshott Retail Ltd | Wholesale & retail | 2018 |
| Mrmoving International Ltd | Transport & logistics | 2026 |
| MSA One Limited | Real estate | 2020 |
| Mselevenplus Limited | Information & communication | 2025 |
| MT Landscapes Limited | Administrative & support | 2016 |
| MT Pipe Services Ltd | Construction | 2024 |
| MTA Private Limited | Real estate | 2024 |
| MTS Live Ltd | Construction | 2020 |
| Mulgrave Road (Sutton) Managements Limited | Households | 1972 |
| Mulgrave Road Freehold Limited | Households | 2009 |
| Mulgrave Road Management Limited | Households | 1989 |
| Mullarch Limited | Professional & scientific | 1983 |
| Multicultural Share Trading Management Limited | Administrative & support | 2022 |
| Multifit Gyms ( UK ) Ltd | Arts & recreation | 2025 |
| MUM Circle Ltd | Arts & recreation | 2025 |
| Munrock Property Holdings Ltd | Real estate | 2018 |
| MUS Consulting Limited | Professional & scientific | 2011 |
| Mutch Engineering Ltd | Manufacturing | 2020 |
| Muuh Heating Ltd | Manufacturing | 2024 |
| Muvishan Ltd | Real estate | 2022 |
| MUX Traders Limited | Wholesale & retail | 2019 |
| MVM Property Solution Ltd | Real estate | 2025 |
| My Workpad Ltd | Information & communication | 2020 |
| Myaa Space Limited | Real estate | 2024 |
| Myconsultation Ltd | Professional & scientific | 2021 |
| Myles Stones Ltd | Real estate | 2021 |
| Mymotifs Limited | Professional & scientific | 2024 |
| MYQ Digital Ltd | Administrative & support | 2025 |
| Myvi Services Ltd | Construction | 2024 |
| N & M Property Enterprises Limited | Real estate | 2024 |
| N E UK Trading Limited | Wholesale & retail | 2014 |
| N.P.D Partnership Limited | Professional & scientific | 1989 |
| N3XA Ltd | Information & communication | 2024 |
| Naapuk Ltd | Real estate | 2025 |
| Nabudo Ltd | Information & communication | 2022 |
| NAD London Ltd | Construction | 2020 |
| Nada GB (2015) Ltd | Professional & scientific | 2015 |
| Nada N.I. Ltd | Professional & scientific | 2022 |
| Nadia Avent Hair Ltd | Other services | 2026 |
| Nadif Ltd | Administrative & support | 2020 |
| Naghansale Ltd | Other services | 2025 |
| Namish Jewels Ltd | Manufacturing | 2026 |
| NAN Mascorro Limited | Information & communication | 2019 |
| Nanyowa Healthcare Limited | Health & social care | 2024 |
| Narcom Ltd | Professional & scientific | 2009 |
| Nasam Consulting Ltd | Professional & scientific | 2026 |
| Nasir Driving Services Ltd | Education | 2026 |
| Nasjee Ltd | Wholesale & retail | 2024 |
| Natalie Potts Coaching Limited | Professional & scientific | 2019 |
| National Black Parents Association UK C.I.C. | Health & social care | 2022 |
| National Utility Hub Ltd | Energy | 2021 |
| Nationwide Fleet Services Ltd | Wholesale & retail | 2018 |
| Nattyblaze UK Ltd | Wholesale & retail | 2024 |
| Natural a Colourful World Limited | Professional & scientific | 2015 |
| Natural Development Ltd | Construction | 2004 |
| Natural Spaces Limited | Administrative & support | 2013 |
| NAV Consultancy Limited | Information & communication | 2010 |
| NAV Homes Limited | Real estate | 2022 |
| NB Stone Limited | Construction | 2009 |
| Nebula 7 Limited | Administrative & support | 2018 |
| Nector Accountancy Services Ltd | Information & communication | 2013 |
| Neeve Management Ltd | Real estate | 2024 |
| Nelson Court Freehold Limited | Households | 2007 |
| Nema Designs Limited | Professional & scientific | 2007 |
| Nemean Property Ltd | Real estate | 2024 |
| Neola Ltd | Other services | 2023 |
| Nephin Limited | Administrative & support | 2016 |
| Nerava Limited | Information & communication | 2025 |
| Nerovix Limited | Manufacturing | 2026 |
| Nesom Limited | Health & social care | 2017 |
| NET Zero Reality Limited | Information & communication | 2024 |
| Netcipher Technologies Ltd | Wholesale & retail | 2026 |
| Netcom Enterprises Limited | Information & communication | 2004 |
| Netmac Limited | Real estate | 1989 |
| Neville Stubbs Limited | Real estate | 1984 |
| New Chicken World Limited | Hospitality | 2020 |