| Medon Limited | Professional & scientific | 1987 |
| Medtech Lead Ltd | Administrative & support | 2024 |
| Medtech UK Limited | Health & social care | 2021 |
| Meesu Overseas Limited | Professional & scientific | 2024 |
| Merida Glazing Solutions Ltd | Construction | 2025 |
| Meritglen Limited | Professional & scientific | 1890 |
| Metro Helper Ltd | Information & communication | 2026 |
| MFI Swelam Limited | Health & social care | 2015 |
| MGS Refurbishment Ltd | Construction | 2022 |
| Michael Angelo Publishing Ltd | Information & communication | 2013 |
| Michael Cooper (UK) Limited | Arts & recreation | 2007 |
| Millcrest Computer Consultants Limited | Information & communication | 1997 |
| Millennium Consulting Ltd | Professional & scientific | 2023 |
| Milo Motorsport Ltd | Manufacturing | 2022 |
| Miltech International Limited | Manufacturing | 1999 |
| Mima Design Studio Ltd | Professional & scientific | 2021 |
| Mina Motors Ltd | Wholesale & retail | 2021 |
| Mind Motivations UK Limited | Administrative & support | 2008 |
| Mindarchitekt Limited | Other services | 2007 |
| Miniature Model Making Ltd | Professional & scientific | 2023 |
| Miracle IT Systems Limited | Information & communication | 2013 |
| Mirror My Day Ltd | Professional & scientific | 2018 |
| Mister Concrete MIX Ltd | Manufacturing | 2018 |
| MJC Consulting Services Limited | Administrative & support | 2008 |
| MK Sons Holdings Limited | Hospitality | 2021 |
| ML Financial Services Limited | Financial services | 2025 |
| MLG Investments Ltd | Real estate | 2026 |
| MME Commercial Limited | Real estate | 2025 |
| MME Property Investments Limited | Real estate | 2024 |
| MME Ventures Limited | Other services | 2016 |
| MNC Facility Management Limited | Information & communication | 2024 |
| MNM Properties London Ltd | Real estate | 2020 |
| MO Commercial Property Ltd | Construction | 2025 |
| Mobile Tyre Tech Limited | Wholesale & retail | 2024 |
| Modu Technologies Limited | Real estate | 2023 |
| Mono Consultancy Solutions Ltd | Administrative & support | 2016 |
| Montanet Investments Limited | Extraterritorial | 1991 |
| Monte Laguna 2 Limited | Hospitality | 2011 |
| Monte Laguna Limited | Hospitality | 2009 |
| Montessori Leaders Surrey Ltd | Professional & scientific | 2021 |
| MOO Acquisitions Ltd | Construction | 2020 |
| Mordstone Accounting Ltd | Administrative & support | 2023 |
| Mori Sushi Limited | Hospitality | 2022 |
| Morris Coastal Roofing Limited | Construction | 2024 |
| Motion Racing Ltd | Professional & scientific | 2024 |
| Motovo Holdings Ltd | Wholesale & retail | 2025 |
| Mountblue Limited | Wholesale & retail | 2025 |
| Mountblue Realty Limited | Real estate | 2024 |
| Movie & Media Accountancy Limited | Professional & scientific | 2022 |
| Moving Picture Logistics Ltd | Administrative & support | 2018 |
| MR Gutter Limited | Construction | 2002 |
| MR Lifestyle Limited | Real estate | 2021 |
| MRC Films Ltd | Information & communication | 2025 |
| MRS Fudge Ltd | Hospitality | 2022 |
| MS Auctions Limited | Real estate | 2013 |
| MSD Vehicles Ltd | Wholesale & retail | 2024 |
| MSG Catering Ltd | Hospitality | 2015 |
| MSG Pro Limited | Transport & logistics | 2016 |
| MT & at Sales Ltd | Wholesale & retail | 2025 |
| MTM Services London Ltd | Professional & scientific | 2019 |
| Mubarak Real Estate Investments Limited | Real estate | 2024 |
| Mulberry Digital Solutions Limited | Information & communication | 2014 |
| Multiple Systems Limited | Administrative & support | 2010 |
| Munro CGI Ltd | Professional & scientific | 2025 |
| Muntrose Ltd | Information & communication | 2019 |
| MV Healthcare Limited | Health & social care | 2025 |
| Mwjs Risk & Control Services Ltd | Administrative & support | 2014 |
| My AI Assistant Ltd | Professional & scientific | 2023 |
| My Electric Services UK Limited | Construction | 2021 |
| My GRS Limited | Construction | 2016 |
| My Home Personal Trainer Limited | Other services | 2019 |
| My Living Options Limited | Real estate | 2023 |
| MYA Care Limited | Health & social care | 2024 |
| MYA Works Limited | Administrative & support | 2026 |
| MZ Properties London Limited | Real estate | 2019 |
| N&M Shores Limited | Households | 2019 |
| N.F K9 Unit Ltd | Administrative & support | 2016 |
| Nails by Mikyb Ltd | Other services | 2025 |
| Nandha Commercial Property Ltd | Real estate | 2025 |
| Nandha Property Management Ltd | Real estate | 2016 |
| Naya Cars Limited | Wholesale & retail | 2024 |
| Nednil Limited | Real estate | 2006 |
| Needs Goals Ltd | Professional & scientific | 2018 |
| Neptune RPO Limited | Administrative & support | 2021 |
| Netsurrey Ltd | Information & communication | 2021 |
| Network Property Brokers Limited | Real estate | 2019 |
| New Dawn Garden Life Ltd | Administrative & support | 2009 |
| Newdawn PG Ltd | Real estate | 2023 |
| News Extra Ltd | Wholesale & retail | 2026 |
| Next Employment Limited | Administrative & support | 1989 |
| Nextonline Limited | Professional & scientific | 2000 |
| Nextwave Technology Limited | Professional & scientific | 1992 |
| NG Heating Services Limited | Construction | 2021 |
| NH Group Investments Ltd | Real estate | 2023 |
| NI & Paye Limited | Professional & scientific | 2017 |
| Nick R&D Ltd | Construction | 2020 |
| Nico Gardens Limited | Other services | 2025 |
| Nicusor Ltd | Construction | 2025 |
| Niels Skov Investment Ltd | Financial services | 2025 |
| Nirjooni Limited | Hospitality | 2018 |