| Mitchell Interiors (NW) Ltd | Construction | 2022 |
| Mitie Brands Ltd | Wholesale & retail | 2019 |
| Mitzey Limited | Wholesale & retail | 2019 |
| MJ Talent Solutions Ltd | Professional & scientific | 2025 |
| Mjacatering Ltd | Hospitality | 2025 |
| MJB Automotive Solutions Limited | Transport & logistics | 2020 |
| MJF Bitton Ltd | Professional & scientific | 2025 |
| MJF Consulting Limited | Professional & scientific | 2020 |
| MJH Propco Limited | Real estate | 2023 |
| MJK Corporate Services Ltd | Professional & scientific | 2019 |
| MJM Performance Limited | Arts & recreation | 2026 |
| Mjptv Ltd | Professional & scientific | 2021 |
| Mjtch Investments Limited | Financial services | 2023 |
| MKX Servicess Ltd. | Information & communication | 2022 |
| MLK Event Ltd | Hospitality | 2020 |
| MLM Projects Limited | Professional & scientific | 2018 |
| Mlsdistributions Ltd | Wholesale & retail | 2025 |
| Mmap Limited | Real estate | 2023 |
| MMC Fittings Limited | Wholesale & retail | 2018 |
| MMT Healthcare Ltd | Health & social care | 2019 |
| MNM Capital Investments Ltd | Real estate | 2025 |
| MNM Healthcare Services Limited | Health & social care | 2016 |
| Mobbs & Croft Holdings Limited | Financial services | 2016 |
| Moborn Holdings Limited | Professional & scientific | 2020 |
| Moda by Alex Ltd | Other services | 2026 |
| Modd Properties & Investments Limited | Real estate | 2017 |
| Modern Seller Ltd | Information & communication | 2023 |
| Modo Interiors and Contracts Ltd | Other services | 2014 |
| Mojo Interior Design Ltd | Professional & scientific | 2026 |
| Mojo Property Investments Ltd | Real estate | 2016 |
| Momentum Instore Limited | Construction | 1993 |
| Monadi Limited | Professional & scientific | 2025 |
| Monarch Oaks Residents Management Company Limited | Households | 2023 |
| Monday Feels Limited | Information & communication | 2026 |
| Mondofin UK Limited | Water & waste | 2020 |
| Moneta Holdings Ltd | Financial services | 2016 |
| Money Surgery Holdings Limited | Financial services | 2014 |
| Moneybox Later Life Limited | Financial services | 2020 |
| Moneybox Wills and Trusts Limited | Professional & scientific | 2020 |
| Moneybrain Advice Ltd | Financial services | 2012 |
| Moneybrain Ltd | Financial services | 2007 |
| Monks Heath Limited | Wholesale & retail | 2025 |
| Montano MAC Ltd | Hospitality | 2024 |
| Montgomery Accountancy and Taxation Services Limited | Professional & scientific | 2004 |
| Montgomery Consulting Limited | Professional & scientific | 1998 |
| Montgomery Duffle Limited | Manufacturing | 2003 |
| Montgomery Watt Lettings Ltd | Real estate | 2025 |
| Monument Therapeutics Limited | Professional & scientific | 2019 |
| Moorhill 1962 Limited | Extraterritorial | 2013 |
| Moorland Clinic Limited | Health & social care | 2022 |
| Moose Beans Ltd | Extraterritorial | 2026 |
| Moose Coffee (UK) Limited | Hospitality | 2009 |
| Moose Coffee Ltd | Hospitality | 2019 |
| Mootiful Limited | Wholesale & retail | 2020 |
| Morgans Incorporated Ltd | Professional & scientific | 2021 |
| Morphettal Ltd | Real estate | 2025 |
| Morris Fire & Security Limited | Administrative & support | 2021 |
| Morris Rowe Services Ltd | Professional & scientific | 2014 |
| Morso Spares Direct Ltd | Construction | 2012 |
| Mortgage Kart Advisors Limited | Financial services | 2019 |
| Mortgage Kart Brokers Limited | Financial services | 2025 |
| Mortgage Kart Limited | Information & communication | 2017 |
| Mortgage Services Warehouse Ltd | Financial services | 2015 |
| Mortrucking Limited | Transport & logistics | 2017 |
| Morzine Limited | Administrative & support | 2022 |
| Mosgray Consultants Ltd | Administrative & support | 2010 |
| Moss Bank Properties LLP | | 2009 |
| Moss Bridge Properties Limited | Extraterritorial | 2015 |
| Mossy Adventurers Ltd | Education | 2023 |
| Motac Holdings Ltd | Professional & scientific | 2001 |
| Motac Neuroscience Limited | Professional & scientific | 1999 |
| Motion Motives Ltd | Extraterritorial | 2020 |
| Moto Classica Limited | Transport & logistics | 2019 |
| Motofinance Group Ltd | Financial services | 2026 |
| Motorcycle Parts Hub Limited | Wholesale & retail | 2023 |
| Motorcycle Trade Ltd | Wholesale & retail | 2017 |
| Motorexpress Limited | Construction | 2001 |
| Motoring.Co.Uk Limited | Professional & scientific | 2007 |
| Mottram Holdings Ltd | Financial services | 2026 |
| Mottram Interiors Group Limited | Professional & scientific | 2017 |
| Mottram Interiors Trustees Limited | Professional & scientific | 2023 |
| Mottram ST. Andrew Primary Academy | Education | 2011 |
| Moulina Limited | Wholesale & retail | 2016 |
| Mountain Equipment Limited | Extraterritorial | 1968 |
| Mova Medical Ltd | Health & social care | 2025 |
| Move IT to Cloud Limited | Manufacturing | 2023 |
| Move Studios Ltd | Health & social care | 2023 |
| Movie Posters Ltd | Wholesale & retail | 2025 |
| Movin Technology Limited | Information & communication | 2024 |
| Moytech Consulting Ltd | Professional & scientific | 2015 |
| Mozu Studio Ltd | Health & social care | 2025 |
| MPA Leisurewear Limited | Wholesale & retail | 2009 |
| Mpgen Ltd | Administrative & support | 2011 |
| MPK Investments Limited | Other services | 2016 |
| MR C'S Office Furniture Limited | Wholesale & retail | 1990 |
| MR Construction Services(Macclesfield) Ltd | Construction | 2021 |
| MR Fone Macclesfield Ltd | Wholesale & retail | 2023 |
| MR Oliver David Walmsley Limited | Hospitality | 2025 |
| MR Woods Timber Supplies Limited | Manufacturing | 2019 |
| MRB Drainage Limited | Professional & scientific | 2009 |