| MKD Contracting London Ltd | Construction | 2026 |
| ML Legacy Properties Ltd | Construction | 2024 |
| Mlem Limited | Other services | 2017 |
| MLP Properties & Developments Ltd | Real estate | 2024 |
| Mmjm Properties 1 Ltd | Real estate | 2022 |
| Mobella Design Ltd | Professional & scientific | 2024 |
| Mojo Padel Limited | Arts & recreation | 2024 |
| Momo & Pala Ltd | Wholesale & retail | 2025 |
| Money Factors Ltd | Financial services | 2010 |
| Monster Consulting Ltd | Wholesale & retail | 2018 |
| Montelmo Holding Ltd | Manufacturing | 2016 |
| Montgomerie & SON Limited | Agriculture & fishing | 2020 |
| Montpellier Investment Holdings (UK) Limited | Professional & scientific | 2013 |
| Montpellier Resourcing Associates Limited | Administrative & support | 2020 |
| Montrose Trees Ltd | Agriculture & fishing | 2014 |
| Mookistar Consultancy Ltd | Professional & scientific | 2019 |
| Moor Accountancy and Tax Services Ltd | Professional & scientific | 2022 |
| Moore and Moore Plants Ltd | Wholesale & retail | 2022 |
| Moores Motor Services Limited | Wholesale & retail | 2003 |
| Moose Management Limited | Professional & scientific | 2011 |
| More Events Logistics Ltd | Other services | 2021 |
| More Pepper Limited | Administrative & support | 2020 |
| More Strategic UK Limited | Professional & scientific | 2015 |
| Moreland 25 Ltd | Real estate | 2025 |
| Morgan Developments Consortium Ltd | Administrative & support | 2022 |
| Morgan Richardson Limited | Financial services | 1994 |
| Morley Consulting Limited | Professional & scientific | 1998 |
| Morley Consulting Training Limited | Professional & scientific | 2013 |
| Morris Educational Consultancy Limited | Education | 2023 |
| Mortar Properties and Investments Ltd | Real estate | 2017 |
| Mortgage Simple Limited | Financial services | 2018 |
| Motor Lawyers Limited | Professional & scientific | 2005 |
| Motorcade Spain Limited | Wholesale & retail | 2013 |
| Motortrak Limited | Information & communication | 2018 |
| Mottainai Consulting Ltd | Professional & scientific | 2010 |
| Mottle Media Services Ltd | Administrative & support | 2017 |
| Mount Brothers Limited | Hospitality | 2012 |
| Moyan Capital Advisory Limited | Professional & scientific | 2024 |
| Moylan Construction Limited | Construction | 2020 |
| Moysie Management Limited | Professional & scientific | 2012 |
| MP Electrical Services (Essex) Limited | Construction | 2014 |
| MP2P Limited | Professional & scientific | 2015 |
| MPK Engineering Limited | Manufacturing | 2017 |
| MR Initiate Ltd | Professional & scientific | 2021 |
| MR James Limited | Health & social care | 2019 |
| MR Steeds of London Ltd | Other services | 2021 |
| MR. Wilde Ltd | Wholesale & retail | 2020 |
| Mr.Choppers Ltd | Other services | 2020 |
| MRE Medics Ltd | Health & social care | 2025 |
| MRH Plumbing and Heating Services Limited | Construction | 2018 |
| MRM Facilities Management Limited | Construction | 2018 |
| MRS Mop's Cleaning Services Ltd | Administrative & support | 2023 |
| MS2 Limited | Real estate | 2013 |
| MTB Maintenance Limited | Real estate | 2016 |
| MTK Connect Ltd | Information & communication | 2015 |
| MTK Holdings Ltd | Financial services | 2015 |
| Mudd Partners LLP | | 2016 |
| Muddy Welly Ltd | Other services | 2021 |
| Mumble Leisure Limited | Wholesale & retail | 2011 |
| Music 4 Limited | Information & communication | 2001 |
| Muze Design Ltd | Professional & scientific | 2022 |
| Mvln Limited | Professional & scientific | 2012 |
| Mwitts Cleaning Services Ltd | Administrative & support | 2010 |
| MWN Accounting Services Limited | Professional & scientific | 2024 |
| MWP (Ramses) Limited | Extraterritorial | 2013 |
| My London IFA Ltd | Financial services | 2012 |
| My Public Notice Limited | Extraterritorial | 2025 |
| My Virtual Recruit Limited | Administrative & support | 2026 |
| Mygymbuddy Ltd | Information & communication | 2023 |
| Myla & MI Ltd | Wholesale & retail | 2026 |
| N B Boutique Limited | Wholesale & retail | 2024 |
| N Brunning Consultants Ltd | Professional & scientific | 2025 |
| N J L Accounting Services Limited | Professional & scientific | 1994 |
| N&W Developments Ltd | Construction | 2026 |
| N.C Sales Limited | Wholesale & retail | 2021 |
| N2 Studio Limited | Professional & scientific | 2016 |
| Nags Head Billericay Ltd | Hospitality | 2024 |
| NAJ Business Solutions Limited | Professional & scientific | 2015 |
| Naomi Sayers Ltd | Education | 2026 |
| Nashrock Property Management Limited | Real estate | 2023 |
| Nashrock Recruitment Ltd | Administrative & support | 2014 |
| Nathan Klein Ltd | Arts & recreation | 2020 |
| Nathan Marsden Copywriting Ltd. | Arts & recreation | 2020 |
| Nature's ARM Limited | Wholesale & retail | 2018 |
| Navarre Construction Limited | Professional & scientific | 1986 |
| Navy Light Limited | Administrative & support | 2022 |
| NC Fisheries Limited | Agriculture & fishing | 2009 |
| NCJ Contracts Ltd | Construction | 2013 |
| NCT Services Limited | Information & communication | 2008 |
| NDJ Property Management Limited | Real estate | 2025 |
| Ndsp Consultancy Limited | Financial services | 2025 |
| Nealcar Direct Ltd | Wholesale & retail | 2024 |
| NEB Interiors Limited | Construction | 2017 |
| Nedcom Ltd | Manufacturing | 2007 |
| Nelliham Ltd | Real estate | 2021 |
| Neovalle Limited | Information & communication | 2015 |
| NES Group ( UK ) Limited | Professional & scientific | 2020 |
| Network Finder Limited | Extraterritorial | 2013 |
| Neural Wing Limited | Manufacturing | 2026 |
| New Heath Portfolio Limited | Real estate | 1999 |