| Mnab Enterprises Ltd | Wholesale & retail | 2009 |
| MNG Facilities Ltd | Construction | 2024 |
| MNH Heat & Energy Trading Ltd | Wholesale & retail | 2026 |
| MO Uddin Limited | Hospitality | 2018 |
| Mobileautoworks Ltd | Wholesale & retail | 2025 |
| MOD Ltd | Other services | 2017 |
| Modaplanta Ltd | Administrative & support | 2025 |
| Modely Rungen LLP | | 2007 |
| Mofar Ltd | Information & communication | 2018 |
| Mohammadia Company Ltd | Hospitality | 2014 |
| Molesey Air Conditioning Ltd | Professional & scientific | 2018 |
| Momodogx Ltd | Professional & scientific | 2023 |
| Mondig Property Ltd | Real estate | 2025 |
| Money Tree Investments Ltd | Real estate | 2021 |
| Monkeymind Limited | Education | 2023 |
| Monmouth Developments Limited | Construction | 2004 |
| Montclair Marketing Limited | Professional & scientific | 2024 |
| Monte Bianco Coffee Ltd | Hospitality | 2024 |
| Monzy Medical UK Ltd | Health & social care | 2019 |
| Moodi Properties Limited | Real estate | 2026 |
| Mooiplaas Limited | Construction | 2017 |
| Moonstone Properties Ltd | Real estate | 2022 |
| Moor Management Company Limited | Professional & scientific | 1986 |
| Moorad Choudhry Financial Limited | Professional & scientific | 2016 |
| Moore Sport Media Limited | Other services | 2016 |
| Moorhouse Properties Limited | Real estate | 1984 |
| More MED Ltd | Wholesale & retail | 2024 |
| More Than Carers Limited | Administrative & support | 2017 |
| Morgan's Dairy Enterprises Limited | Financial services | 2015 |
| Morgan's Dairy Holdings Limited | Financial services | 2018 |
| Morgan's Dairy Properties Limited | Real estate | 2015 |
| Morgan’S Dairy Limited | Wholesale & retail | 2015 |
| MOS Performance Ltd | Wholesale & retail | 2021 |
| Mosaic Systems Limited | Information & communication | 2006 |
| Motion Training Ltd | Arts & recreation | 2016 |
| Motocode Ltd | Information & communication | 2016 |
| Mount Court (Kingston Hill) Residents Association Limited | Households | 1969 |
| Mountfitchet Aircraft Limited | Transport & logistics | 2016 |
| Mountfitchet Group Limited | Professional & scientific | 2022 |
| Mountfitchet Limited | Professional & scientific | 2015 |
| Mountfitchet Property Limited | Real estate | 2021 |
| Mountford & Co Financial Ltd | Financial services | 2019 |
| Mountstephen Investments Limited | Real estate | 1990 |
| Moviesbox Global Limited | Information & communication | 2025 |
| Mozven Properties Limited | Real estate | 2022 |
| MPA3 Logistics Ltd | Transport & logistics | 2020 |
| MPN Arts Ltd | Professional & scientific | 2026 |
| Mptrue Ltd | Arts & recreation | 2025 |
| MR & MRS Olive UK Ltd | Wholesale & retail | 2016 |
| MR and MRS Frame Limited | Real estate | 2006 |
| MRA Secretaries Limited | Administrative & support | 2008 |
| MRA Shareholders Limited | Administrative & support | 2006 |
| MRC Services UK Limited | Professional & scientific | 2002 |
| MRE Partners Ltd | Real estate | 2017 |
| MRG Shareholders Limited | Administrative & support | 2008 |
| Mrkakes Consulting Ltd | Professional & scientific | 2022 |
| MRM Impo Ltd | Wholesale & retail | 2018 |
| MRN Computing Limited | Information & communication | 2025 |
| MRT Capital Limited | Information & communication | 2023 |
| Mrym (UK) Ltd | Wholesale & retail | 2023 |
| MS & Co Accounts Ltd | Professional & scientific | 2022 |
| MS Pomelo Studios Ltd. | Wholesale & retail | 2015 |
| Msav Limited | Wholesale & retail | 2025 |
| MSB Mortgage Services Ltd | Financial services | 2020 |
| Mssuk Ltd | Wholesale & retail | 2021 |
| Mstrd Limited | Information & communication | 2014 |
| Msts - Drylining Ltd | Construction | 2017 |
| MTP Heating and Plumbing Services Ltd | Construction | 2026 |
| Muddy Paws Sales Ltd | Wholesale & retail | 2025 |
| Muddymen Ltd | Real estate | 2022 |
| Mudita Holdings Ltd | Hospitality | 2020 |
| Mudita Properties Ltd | Hospitality | 2020 |
| Mughal Investors Ltd | Real estate | 2025 |
| Multea Choice Twickenham Ltd | Wholesale & retail | 2022 |
| Multea HQ Ltd | Wholesale & retail | 2023 |
| Multilingual Ltd | Professional & scientific | 2018 |
| Multiple Consultants Ltd | Wholesale & retail | 2014 |
| Multipoint Networks Limited | Information & communication | 2010 |
| Multitudes 1979 Ltd | Real estate | 2026 |
| MUM Love C.I.C. | Professional & scientific | 2023 |
| Mumzoom Ltd | Wholesale & retail | 2020 |
| Murphee Limited | Information & communication | 2024 |
| Mustard Marketing Limited | Extraterritorial | 2009 |
| Muzzyair Chauffeurs Ltd | Transport & logistics | 2024 |
| Muzzyair Ltd | Transport & logistics | 2022 |
| MV Consult Ltd | Professional & scientific | 2024 |
| MVB Building Services Ltd | Construction | 2018 |
| MVR Supplies Ltd | Manufacturing | 2012 |
| MVS Guardian Sheild Services Limited | Professional & scientific | 2024 |
| MW Square Ltd | Extraterritorial | 2024 |
| MWM United Ltd | Wholesale & retail | 2017 |
| My Promotor Ltd | Professional & scientific | 2020 |
| My Wealthmaster Limited | Information & communication | 2023 |
| Mycroft Systems Limited | Information & communication | 2019 |
| Myra Consulting Ltd | Professional & scientific | 2024 |
| Mythras Technologies Ltd | Information & communication | 2026 |
| MZ Construction (UK) Limited | Construction | 2015 |
| MZS Property Ltd | Real estate | 2024 |
| MZS Regulatory Consultancy Ltd | Public administration | 2019 |
| N & T Stone and Tiling Ltd | Construction | 2025 |