| Magma Wealth Management Limited | Financial services | 2012 |
| Magna 4 Limited | Real estate | 2024 |
| Magnum Driver Hire Limited | Transport & logistics | 2007 |
| Magpie Lodge Farm Ltd | Information & communication | 2019 |
| Mahant Global Ltd | Wholesale & retail | 2025 |
| Maharjan Limited | Health & social care | 2021 |
| Mahatma Limited | Information & communication | 2007 |
| Maid in Rugby Limited | Administrative & support | 2008 |
| Mailshark Ltd | Information & communication | 2023 |
| Maintenance Connect Ltd | Construction | 2021 |
| Maintenance Made Easy Ltd | Administrative & support | 2017 |
| Majestic Dwellings Ltd | Real estate | 2025 |
| Make Paws Dog Walks & Pet Sitting Ltd | Other services | 2023 |
| Makers' EYE Limited | Wholesale & retail | 2011 |
| Mala Beds Limited | Wholesale & retail | 2023 |
| Malabar Plant Ltd | Administrative & support | 2026 |
| Malayalam UK Ltd | Information & communication | 2017 |
| Malik Business Experts Limited | Wholesale & retail | 2020 |
| Mallard Holdings LLP | | 2016 |
| Mallick Smile Limited | Health & social care | 2026 |
| Mallock PDI (Rugby) Limited | Transport & logistics | 2024 |
| Mallory Irvine Ltd | Real estate | 2020 |
| Malmbergs (UK) Limited | Wholesale & retail | 1994 |
| Malpass Landscaping Limited | Administrative & support | 2019 |
| Malpass Services Daventry Limited | Manufacturing | 2020 |
| Malpass Services Ltd | Agriculture & fishing | 2016 |
| Malta Baggie Limited | Information & communication | 2022 |
| Maltek Global Ltd | Wholesale & retail | 2025 |
| Mama B'S Rugby Limited | Hospitality | 2025 |
| Mamamona Ltd | Manufacturing | 2025 |
| Mana Organic Cosmetics Ltd | Wholesale & retail | 2025 |
| Manatsa Properties Ltd | Real estate | 2024 |
| Manchester House Management Company Limited | Households | 1992 |
| Mandala Women’S Wellbeing Project CIC | Education | 2026 |
| Manga and Sons Entreprise Limited | Transport & logistics | 2025 |
| Mangabdan 25 Ltd | Real estate | 2025 |
| Mann Telecom Ltd | Information & communication | 2009 |
| Manna Consulting Limited | Professional & scientific | 2025 |
| Manoflow Limited | Information & communication | 2026 |
| Manohaul (UK) Ltd | Other services | 2009 |
| Manoprop One Ltd | Financial services | 2025 |
| Manor Construction & Maintenance Ltd | Construction | 2018 |
| Manor Farm Fields Ltd | Real estate | 2024 |
| Manor Farm Management Company (Flecknoe) Limited | Households | 1992 |
| Manor House Rugby Ltd | Households | 2024 |
| Manotan (Omni) Limited | Information & communication | 2025 |
| Manotan Consulting Ltd | Professional & scientific | 2019 |
| Manotan Group (Holdings) Ltd | Information & communication | 2026 |
| Manotan Limited | Information & communication | 2025 |
| Manovate Limited | Professional & scientific | 2026 |
| Manshi Bradford Ltd | Wholesale & retail | 2025 |
| Manshi Broad Lane Ltd | Wholesale & retail | 2025 |
| Manshi Manchester Ltd | Wholesale & retail | 2024 |
| Manshi Properties Ltd | Real estate | 2023 |
| Manshi Retail Ltd | Wholesale & retail | 2021 |
| Manshi Shriji Ltd | Real estate | 2025 |
| Manuals Direct Ltd | Manufacturing | 2019 |
| Manufaktura of Gifts Ltd | Administrative & support | 2013 |
| Manufekai Ltd | Health & social care | 2019 |
| MAP Development Consultants Ltd | Real estate | 2024 |
| Maple Lodge Developments Limited | Real estate | 2023 |
| MAR Trans 1989 Ltd | Transport & logistics | 2016 |
| Mara Surveys Ltd | Administrative & support | 2022 |
| Maracleaning& Building Limited | Construction | 2025 |
| Maradiva Ltd | Administrative & support | 2017 |
| Marakair Ltd | Professional & scientific | 2024 |
| Marc ORD Driver Training Ltd | Transport & logistics | 2020 |
| Marc P Foster Ltd | Transport & logistics | 2022 |
| Marc's HGV Transport Ltd | Transport & logistics | 2019 |
| March Court (Rugby) Limited | Real estate | 1982 |
| Marchall Properties Limited | Real estate | 1995 |
| Marcyk Ltd | Transport & logistics | 2018 |
| Marek Ltd | Transport & logistics | 2017 |
| Marek Waszczynski Transport Ltd | Transport & logistics | 2018 |
| Margstan & Associates Limited | Administrative & support | 2003 |
| Mariab Logistics Limited | Transport & logistics | 2025 |
| Marinepix Limited | Professional & scientific | 2007 |
| Mario Jarcu Ltd | Other services | 2021 |
| Mariosor Trans Limited | Transport & logistics | 2020 |
| Mariusz Cielecki Ltd | Extraterritorial | 2017 |
| Mark Smith Haulage Limited | Transport & logistics | 2018 |
| Marketsmeet Limited | Information & communication | 2009 |
| Marley Transport Ltd | Transport & logistics | 2023 |
| Marly Roofing Ltd | Construction | 2021 |
| Marol Ltd | Transport & logistics | 2017 |
| Mars Realty Services Limited | Real estate | 2023 |
| Mars Technology Solution Limited | Information & communication | 2019 |
| Marsh Driving Services Ltd | Extraterritorial | 2012 |
| Marsh Mill Promotions Limited | Manufacturing | 2002 |
| Marsh Vehicle Services (T/A VENUE2VENUE) Ltd | Construction | 2016 |
| Martindale & Co Limited | Construction | 2009 |
| Martiniautomation Ltd | Information & communication | 2022 |
| Marty's Club Ltd | Education | 2002 |
| Martyn Allen Building & Maintenance Ltd | Construction | 2013 |
| Mary Cargo Limited | Transport & logistics | 2025 |
| Marydaryo Limited | Transport & logistics | 2018 |
| Marysmartin Ltd | Health & social care | 2014 |
| Maryukini Care Limited | Administrative & support | 2018 |
| Marzipants Ltd | Manufacturing | 2011 |
| MAS Dodo Healthcare Solutions Limited | Health & social care | 2025 |