| Mark Pulford Joinery Ltd | Construction | 2017 |
| Mark Wilson Ltd | Construction | 2020 |
| Mark Woods Consultancy Group Limited | Professional & scientific | 2025 |
| Mark Yates Ceramic Tile Agency Ltd | Wholesale & retail | 2019 |
| Marked UP CAD Services Limited | Professional & scientific | 2016 |
| Market Station 365 Ltd | Wholesale & retail | 2024 |
| Market Street Barbers Ltd | Other services | 2021 |
| Marl Road Development Ltd | Construction | 2024 |
| Marlborough (NW) Limited | Real estate | 2020 |
| Maronitis Limited | Hospitality | 2024 |
| Marron Control Ltd | Information & communication | 2011 |
| Marsden Crane Hire Limited | Extraterritorial | 1997 |
| Marsden Crane Services Ltd | Construction | 2015 |
| Marsh & Marsh Developments Ltd | Real estate | 2024 |
| Marsh & Marsh Holdings Ltd | Real estate | 2023 |
| Marsh & Marsh Property Group Ltd | Real estate | 2023 |
| Marsh Property Holdings Ltd | Real estate | 2023 |
| Marshall Brown Improvements Limited | Construction | 2021 |
| Marshall Landscapes Limited | Administrative & support | 2019 |
| Marsheal LET Limited | Real estate | 2025 |
| Marshy Media Ltd | Wholesale & retail | 2018 |
| MARTECH80 Ltd | Transport & logistics | 2015 |
| Martin Ainscough Farms Limited | Agriculture & fishing | 1958 |
| Martin Bond Property Auctions Limited | Real estate | 2021 |
| Martin Green Entertainment Management Limited | Arts & recreation | 2017 |
| Martin Thomas Training and Consultancy Ltd | Education | 2022 |
| Martland Mill PUB Company Limited | Hospitality | 2015 |
| Martyn Watson Limited | Education | 2011 |
| Marvilon Ltd | Professional & scientific | 2026 |
| Marwest & Co Limited | Professional & scientific | 1987 |
| Mary O'Shaughnessy Consulting Limited | Administrative & support | 2016 |
| Marylebone Accountancy Services Ltd | Professional & scientific | 2010 |
| Marzan Ltd | Hospitality | 2019 |
| MASCAS1989 Ltd | Transport & logistics | 2025 |
| Mascord Industries Ltd | Financial services | 2025 |
| Mash Light Limited | Construction | 2024 |
| Mason Business Consulting Ltd | Professional & scientific | 2024 |
| Mason Properties Ltd | Real estate | 2013 |
| Masrida | Professional & scientific | 2026 |
| Massist Limited | Information & communication | 2013 |
| Mastepie | Professional & scientific | 2025 |
| Master Pizza Ltd | Hospitality | 2025 |
| Masterpeace Developments Ltd | Real estate | 2018 |
| Mastery of Excellence Ltd | Professional & scientific | 2021 |
| Matako Ltd | Transport & logistics | 2025 |
| Matchstick MEN Limited | Extraterritorial | 2021 |
| Material Solutions Nationwide Limited | Transport & logistics | 2019 |
| Mathan & Brothers Ltd | Wholesale & retail | 2017 |
| Mather Fold Farm Management Company Limited | Households | 2019 |
| Matic Building Services Limited | Construction | 2022 |
| Matrix FSE Ltd | Construction | 2011 |
| Matt Cain Training Ltd | Professional & scientific | 2019 |
| Matt Hills Travel Ltd | Administrative & support | 2023 |
| Matt Monks Property Ltd | Real estate | 2024 |
| Matthew Wakefield Guides Ltd | Information & communication | 2017 |
| Maui Limited | Information & communication | 2023 |
| Mauvers Consulting Ltd | Construction | 2024 |
| Mauwgon Ltd | Information & communication | 2024 |
| Maverick Ventures Trading Ltd | Professional & scientific | 2025 |
| Maverick Ventures UK Holdings Group Ltd | Professional & scientific | 2025 |
| Maverick's Detailing Ltd. | Administrative & support | 2020 |
| MAX Green Ltd | Energy | 2023 |
| MAX Rolle Photography Ltd | Information & communication | 2024 |
| Maxamillion Group Ltd | Construction | 2016 |
| Maxi Roofing Ltd | Construction | 2017 |
| MAXIMES2 Nightclub Ltd | Arts & recreation | 2012 |
| Maximise Education Consultancy Ltd | Education | 2019 |
| Maxwell House Properties Limited | Real estate | 2014 |
| Maxwelly 1 Ltd | Wholesale & retail | 2024 |
| Mayflower Brewery Ltd | Manufacturing | 2013 |
| Mayflower Cottages Conservation Limited | Households | 2006 |
| Mayflower Management Services (North West) Ltd | Financial services | 2018 |
| Mayo Medics Limited | Health & social care | 2013 |
| Mayor Roofing Ltd | Construction | 2025 |
| Mayowill Contracts Limited | Construction | 2024 |
| Maypole Equestrian Centre Limited | Agriculture & fishing | 2004 |
| Mayren's Metalwork Limited | Manufacturing | 2022 |
| Mayson Collective Ltd | Administrative & support | 2026 |
| Maytree Financial Services Ltd | Financial services | 2006 |
| MB Agencies Ltd | Wholesale & retail | 2014 |
| MB and DB Limited | Professional & scientific | 2015 |
| MB Clearances Ltd | Administrative & support | 2017 |
| MB Masonry Northwest Limited | Manufacturing | 2023 |
| MB91 Holdings Ltd | Financial services | 2024 |
| Mbapplications Ltd | Information & communication | 2026 |
| Mbcmk Holdings Limited | Financial services | 2025 |
| Mbcmk Limited | Information & communication | 2023 |
| Mbcmk Properties Limited | Real estate | 2025 |
| MBD Installations Northwest Ltd | Construction | 2025 |
| Mbda Properties Limited | Financial services | 2017 |
| Mbep Ltd | Construction | 2014 |
| MBG Fitted Bedrooms & Furniture Limited | Construction | 2023 |
| MBM Events (NW) Ltd | Administrative & support | 2026 |
| MBR Construction Estimating Ltd | Professional & scientific | 2016 |
| MC Autos Wigan Ltd | Wholesale & retail | 2025 |
| MC Building Works Ltd | Financial services | 2010 |
| MC Finchy Ltd | Other services | 2018 |
| MC Services (Home Improvements) Limited | Construction | 2026 |
| MC Tanning Ltd | Other services | 2022 |
| MC Upholstery Ltd | Other services | 2025 |