| Mayflower Care Homes Limited | Health & social care | 2002 |
| MB Paraplanning Ltd | Administrative & support | 2023 |
| MBD Consultancy Ltd | Professional & scientific | 2021 |
| Mbpl Holdings Ltd | Financial services | 2011 |
| MBT Mechanical Limited | Professional & scientific | 2026 |
| MC Bushy Ltd | Transport & logistics | 2016 |
| MC Sharku Ltd | Hospitality | 2024 |
| MC Vittie Canworks Limited | Manufacturing | 2012 |
| Mccarthy and Taylor Ltd | Hospitality | 2019 |
| Mccoy Electrical Ltd | Construction | 2025 |
| Mccready Property Management Ltd | Households | 2023 |
| Mcdonald and SON Property Ltd | Real estate | 2025 |
| Mcdonald and Thompson Consultancy Limited | Other services | 2012 |
| Mcewan Wallace Limited | Professional & scientific | 2009 |
| Mcewan Wallace Trustees Limited | Professional & scientific | 2018 |
| MCH Developments Wirral Limited | Construction | 2022 |
| Mclaughlin Psychological Services Limited | Health & social care | 2022 |
| Mclintocks Limited | Administrative & support | 2008 |
| Mcsewer Limited | Water & waste | 2018 |
| MD Affinity Schemes Ltd | Financial services | 2012 |
| MD Insurance Services Limited | Financial services | 1998 |
| MD Remedial Contractors Limited | Professional & scientific | 2016 |
| MD Technical Surveyors Limited | Professional & scientific | 2019 |
| MD72 Ltd | Other services | 2020 |
| Mdis (International) Limited | Financial services | 2012 |
| Mdkg Group Ltd | Wholesale & retail | 2026 |
| Me&Nu Cafe Bar Ltd | Hospitality | 2022 |
| Meadowbank Care Limited | Health & social care | 2001 |
| Measure Quote Ltd | Information & communication | 2026 |
| Measured Marketing Ltd | Professional & scientific | 2019 |
| Mechanical Pipework Solutions Ltd | Construction | 2021 |
| Medhurst (North West) Limited | Information & communication | 2004 |
| Media Screen Solutions Limited | Administrative & support | 2021 |
| Mediconsulting Ltd | Health & social care | 2025 |
| Medimac Enterprises Limited | Wholesale & retail | 2024 |
| Mefa Ltd | Hospitality | 2016 |
| Mega Contractors Ltd | Construction | 2026 |
| Meia Refrigeration Ltd | Professional & scientific | 2026 |
| Melard Limited | Construction | 1981 |
| Mello Moose Beverages Ltd | Extraterritorial | 2020 |
| Melt Arts CIC | Education | 2022 |
| Melton Camper and Commercial Hire Ltd | Administrative & support | 2026 |
| Melyr Ltd | Wholesale & retail | 2022 |
| Memcol Limited | Wholesale & retail | 1999 |
| Mendip House Management Company Limited | Real estate | 2004 |
| MEP Measure Limited | Professional & scientific | 2016 |
| Mercury Press and Media Limited | Arts & recreation | 2011 |
| Merilyn Phillips Limited | Wholesale & retail | 2006 |
| Merlec Limited | Construction | 2016 |
| Merriman & Ross Ltd | Manufacturing | 2026 |
| Mersdee Health Limited | Health & social care | 2010 |
| Mersey Aviation Services Limited | Manufacturing | 2015 |
| Mersey Counselling and Therapy Centre | Health & social care | 2011 |
| Mersey Engineering Construction Ltd | Construction | 2013 |
| Mersey Healthcare LLP | | 2022 |
| Mersey Launch Services Ltd | Manufacturing | 2021 |
| Mersey Physio Ltd | Health & social care | 2015 |
| Mersey Rest Ltd | Health & social care | 2024 |
| Merseyside Engine Parts Limited | Wholesale & retail | 2009 |
| Merseyside Esports Limited | Education | 2023 |
| Merseyside Foods Limited | Hospitality | 2025 |
| Merseyside Industrial Supplies Limited | Manufacturing | 2017 |
| Merseyside Metal Services (Holdings) Limited | Financial services | 2023 |
| Merseyside Metal Services Limited | Manufacturing | 1984 |
| Merseyside Networking & Business Referrals Limited | Other services | 2019 |
| Merseyside Revival Trust | Information & communication | 2011 |
| Merseyside Social Dance CIC | Education | 2026 |
| MES Mechanical Engineering Services Limited | Manufacturing | 2009 |
| Mes-Cuts Meals Ltd | Hospitality | 2026 |
| Meta Smart Systems Ltd | Other services | 2022 |
| MF 93 Transport Ltd | Transport & logistics | 2023 |
| MF Management Group Limited | Real estate | 2025 |
| MG Inspection Services (Wirral) Ltd | Administrative & support | 2010 |
| MGE Developments Limited | Financial services | 2019 |
| Mgma Properties Limited | Real estate | 2015 |
| MHB Health Care Ltd | Health & social care | 2020 |
| Miami Tanning Ltd | Other services | 2024 |
| Michael S Hennessy Limited | Health & social care | 2003 |
| Microtek 4U Ltd | Other services | 2016 |
| Midas Property Investors Ltd | Real estate | 2013 |
| Middlewood Vehicle Rentals Limited | Administrative & support | 2024 |
| Miken Electrical Ltd | Construction | 2018 |
| Mildmay Management Limited | Households | 1994 |
| Milk and Honey Limited | Hospitality | 2022 |
| Millbay Services Ltd | Construction | 2022 |
| Millington Properties (North West) Ltd | Real estate | 2023 |
| Millington Removals Ltd | Transport & logistics | 2023 |
| Mimi Mcnaull Podiatry Ltd | Health & social care | 2024 |
| Mindful Markets Limited | Financial services | 2025 |
| Mindset Psychology Ltd | Health & social care | 2017 |
| Mindsetesg Limited | Professional & scientific | 2022 |
| Mirac Miray Huma Ltd | Hospitality | 2025 |
| Mirchi Ltd | Hospitality | 2025 |
| Mirha Wirral Ltd | Hospitality | 2025 |
| Miriam Day Nursery Ltd | Other services | 2015 |
| Miriam Primary Care Limited | Health & social care | 2011 |
| MIRJAN01 Ltd | Real estate | 2026 |
| Mjbs Collective Ltd | Information & communication | 2026 |
| MJR Tipi & Tent Services Ltd | Construction | 2023 |
| MJS Diner Limited | Wholesale & retail | 2025 |