| Models Inc Ltd | Financial services | 2025 |
| Modern Classic Digital Ltd | Professional & scientific | 2022 |
| Modern Pro Roofing UK Limited | Construction | 2025 |
| Modernlondonhouse.Com Limited | Professional & scientific | 2002 |
| Modex Consulting Ltd | Professional & scientific | 2024 |
| Modular Materials Handling Limited | Professional & scientific | 2021 |
| Moena D Ltd | Wholesale & retail | 2023 |
| Moet Hennessy Services UK Limited | Administrative & support | 2012 |
| MOH Computers Limited | Other services | 2002 |
| Mojiworks Limited | Information & communication | 2016 |
| Mojiworks One Limited | Information & communication | 2017 |
| Molecular Medical Solutions Ltd | Professional & scientific | 2022 |
| Mollono Limited | Administrative & support | 2024 |
| Monenti Partners Capital Ltd | Financial services | 2021 |
| Monenti Partners Ltd | Financial services | 2007 |
| Money Wise Media Ltd | Wholesale & retail | 2024 |
| Monkey PIG Developments Ltd | Construction | 2016 |
| Monkeypuzzle Investment Company | Other services | 2017 |
| Monni Limited | Professional & scientific | 2004 |
| Mono Loco Ltd | Arts & recreation | 2024 |
| Monocle Mayhem Limited | Information & communication | 2019 |
| Montadale Limited | Arts & recreation | 2024 |
| Montague Wokingham LP | | 2012 |
| Montburry Estates Limited | Real estate | 2016 |
| Montfort International Limited | Financial services | 1995 |
| Montpellier Lodge Residents Limited | Administrative & support | 1999 |
| Monu Investments Ltd | Real estate | 2022 |
| Monument Solutions Limited | Education | 2014 |
| Moonberry Associates Limited | Professional & scientific | 1999 |
| Moonhouse Films Limited | Information & communication | 2017 |
| Moonshot Marketing Ltd | Professional & scientific | 2014 |
| Moor Bio-Energy Limited | Energy | 2015 |
| Moorcroft Career Management Services Ltd. | Professional & scientific | 2003 |
| Moordale Engineering Limited | Construction | 2025 |
| Moos Property Management Ltd | Households | 2025 |
| Mopane Investments Limited | Real estate | 1999 |
| Morbex Homes Ltd | Construction | 2021 |
| Morbex Ltd | Construction | 2021 |
| Morden Ceilings Limited | Administrative & support | 1987 |
| More Cowbell Ltd | Arts & recreation | 2013 |
| More Human Agency Limited | Information & communication | 2008 |
| More Meals Ltd | Manufacturing | 2022 |
| Moria Consulting Ltd | Professional & scientific | 2016 |
| Moro Trading Limited | Professional & scientific | 2023 |
| Morris & Spooner Limited | Administrative & support | 2024 |
| Mortgage Advice for Everyone Limited | Financial services | 2015 |
| Moss and Homes Limited | Wholesale & retail | 2022 |
| Motion Consultants Limited | Administrative & support | 2004 |
| Motion Music Limited | Information & communication | 1996 |
| Motion Picture House Limited | Administrative & support | 1998 |
| Moto-Ward Limited | Wholesale & retail | 1993 |
| Motoebikes Ltd | Wholesale & retail | 2020 |
| Motolegends Limited | Extraterritorial | 2013 |
| Motor Inventions Ltd | Professional & scientific | 2011 |
| Motorlink Distribution Limited | Transport & logistics | 1991 |
| Motorlink EOT Ltd | Other services | 2018 |
| Motorsport Partnership Limited | Wholesale & retail | 2007 |
| Mould Consulting Limited | Professional & scientific | 2023 |
| Mould Property Limited | Real estate | 2022 |
| Mount Egmont Limited | Information & communication | 2019 |
| Mount Egmont Property Limited | Construction | 2020 |
| Mountain Festival Events Limited | Administrative & support | 2026 |
| Mountside Electrical Ltd | Construction | 2026 |
| Mountside Vista Ltd | Information & communication | 2023 |
| Mouse Manor Limited | Professional & scientific | 2024 |
| Mousebox Limited | Professional & scientific | 2025 |
| MP Cars (Guildford) Ltd | Other services | 2008 |
| MP Recovery Services Ltd | Transport & logistics | 2021 |
| MPL Construction Services 1999 Ltd | Professional & scientific | 2016 |
| MPS Finance & Advisory Ltd | Professional & scientific | 2023 |
| MPS Guildford Limited | Hospitality | 2009 |
| MR Fade Traditional Turkish Barber Ltd | Other services | 2026 |
| MR Silva - Your Move, OUR Drive Limited | Transport & logistics | 2025 |
| MR Solutions Group Limited | Administrative & support | 2014 |
| MR Solutions Limited | Administrative & support | 2015 |
| MR Spectra Limited | Professional & scientific | 2017 |
| MR. Entertainer's Karaoke Ltd | Professional & scientific | 2003 |
| MRR Systems Limited | Professional & scientific | 2002 |
| MS Aldershot Ltd | Other services | 2014 |
| MS Catering Guildford Limited | Hospitality | 2025 |
| MS London Investment Ltd | Real estate | 2022 |
| Msesg Consulting Limited | Information & communication | 2019 |
| MSP Software Limited | Information & communication | 2022 |
| Mstf Limited | Health & social care | 2020 |
| MT & AB Limited | Other services | 2023 |
| MTF Clearpath Consulting Limited | Professional & scientific | 2026 |
| MTH Scaffolding Limited | Construction | 2011 |
| MTN Builds Limited | Construction | 2024 |
| MTR Promotions Limited | Arts & recreation | 2024 |
| MUK Global Trading ( UK ) Limited | Wholesale & retail | 2015 |
| MUK Global Trading H Ltd | Wholesale & retail | 2018 |
| Mulfrey Solutions Ltd | Professional & scientific | 2018 |
| Mulliri Ltd | Hospitality | 2026 |
| Mulroy Architects Ltd | Professional & scientific | 2008 |
| Multea Choice Guildford Ltd | Wholesale & retail | 2025 |
| Multi-Store Limited | Other services | 1997 |
| Multicore Networking Ltd | Construction | 2026 |
| Murrayfield Ventures Limited | Construction | 2026 |
| Murugasu Property Group Ltd | Real estate | 2025 |
| Musgo Management Limited | Construction | 2007 |