| Marnel Estates Ltd | Real estate | 2016 |
| Marque Atelier Ltd | Wholesale & retail | 2026 |
| Marsden House Investments Limited | Real estate | 1997 |
| Marson Joinery & Property Repairs Limited | Construction | 2012 |
| Martbe Limited | Information & communication | 2018 |
| Martin Cooper Construction Limited | Construction | 2007 |
| Martin Jones Transmissions Ltd | Manufacturing | 2014 |
| Martin Motor Group Ltd | Wholesale & retail | 2023 |
| Marubbi Homes Limited | Real estate | 2024 |
| Mary Florence Property Ltd | Real estate | 2021 |
| Masons Timber Products Limited | Manufacturing | 2011 |
| MAT Way Ltd | Transport & logistics | 2024 |
| Matclad Limited | Manufacturing | 2009 |
| Mateo RFM Limited | Hospitality | 2025 |
| Mates Property Group Limited | Real estate | 2025 |
| Matrelanis Limited | Real estate | 2025 |
| Matthew Rose Catering Ltd | Hospitality | 2024 |
| Matthews Electrical (NW) Limited | Construction | 2021 |
| Mauna KEA Limited | Financial services | 2017 |
| Maurice's Bar Ltd | Hospitality | 2024 |
| Maverick Diagnostics Limited | Manufacturing | 2017 |
| Mavi Properties (the Three Eagles) Ltd | Real estate | 2018 |
| Mavi Properties Limited | Real estate | 2018 |
| MAX Pump Limited | Construction | 2021 |
| MAX Woodcock Ltd | Construction | 2003 |
| Maximus Roofing and Building Ltd | Construction | 2026 |
| Maxrae Consulting Ltd | Professional & scientific | 2025 |
| Maya Landscaping & Driveways Limited | Administrative & support | 2023 |
| Mayo Animal Healthcare Limited | Wholesale & retail | 2016 |
| Mazen Sons Limited | Hospitality | 2024 |
| MBF Financial Services Ltd | Professional & scientific | 2006 |
| MBM Accountancy Limited | Professional & scientific | 2019 |
| Mbmimports Limited | Wholesale & retail | 2023 |
| MBP Engineering (Wrexham) Ltd | Construction | 2015 |
| Mccarthy Distribution Ltd | Transport & logistics | 1997 |
| Mccarthy Haulage Limited | Transport & logistics | 2008 |
| Mccarthycladding Ltd | Construction | 2020 |
| Mcclelland & Robinson Properties Limited | Real estate | 2023 |
| Mcgivern Pubs Limited | Hospitality | 2008 |
| MCK Inventories Ltd | Real estate | 2022 |
| Mckay Melia Limited | Construction | 2022 |
| Mcnabb Holdings Ltd | Real estate | 2021 |
| MCP Property Management Ltd | Real estate | 2019 |
| Mcphee Group (UK) Limited | Financial services | 2020 |
| MCR Independent Social Work Consultancy Ltd | Health & social care | 2014 |
| MCS Engineering Group Ltd | Manufacturing | 2012 |
| MD Fruits Ltd | Wholesale & retail | 2020 |
| MD Specialist Cleaning Services Limited | Administrative & support | 2022 |
| MDC Financial Management Limited | Financial services | 2021 |
| MDC Financial Planning Limited | Financial services | 2020 |
| MDC Financial Services Limited | Financial services | 2021 |
| MDP Property Limited | Real estate | 2017 |
| Meadow View Properties NW Limited | Real estate | 2023 |
| Meadows General Store Ltd | Wholesale & retail | 2024 |
| Meats of the World at Christmas Limited | Hospitality | 2014 |
| Mech-Spark Ltd | Professional & scientific | 2020 |
| Media Fields Limited | Information & communication | 2003 |
| Medicare Consultancy North West Ltd | Health & social care | 2010 |
| Medortus (UK) Ltd | Professional & scientific | 2011 |
| Mega Mouse Media Ltd | Professional & scientific | 2024 |
| Meirion. L. Jones and SON Limited | Other services | 2001 |
| MEL (Wrexham) Ltd | Real estate | 2021 |
| Melbourne Commercial Company Limited | Real estate | 2004 |
| Melbrian Entertainments Limited | Hospitality | 2013 |
| Melia Propco Limited | Hospitality | 2020 |
| Mema Properties Ltd | Real estate | 2023 |
| Memmori Ltd | Information & communication | 2017 |
| Memorial Buildings (Ruthin) Management Company Limited | Real estate | 2006 |
| Memory Healthcare Ltd | Health & social care | 2023 |
| Menopause Connect & Thrive CIC | Education | 2025 |
| Meowve Cheshire & North Wales Ltd | Professional & scientific | 2025 |
| Merak Limited | Wholesale & retail | 2024 |
| Mere Court Development Limited | Construction | 2014 |
| Meritor Gyms Ltd | Arts & recreation | 2025 |
| Meritor Machines Ltd | Wholesale & retail | 2025 |
| Merlin Global Ltd | Wholesale & retail | 2020 |
| Merlin Systems Limited | Information & communication | 1979 |
| Mersey Ventures Limited | Hospitality | 2025 |
| Mert 1 Ltd | Hospitality | 2025 |
| Mertafov Transport Limited | Transport & logistics | 2026 |
| MF Brickwork Limited | Construction | 2026 |
| MGN Group Ltd | Wholesale & retail | 2020 |
| MGP Accountants Limited | Professional & scientific | 2011 |
| MH Food and Beverage Limited | Hospitality | 2024 |
| MH Taytoes Ltd | Hospitality | 2025 |
| MH Travel (North Wales) Ltd | Transport & logistics | 2022 |
| MHI Polymer Ltd | Wholesale & retail | 2026 |
| MHM Holt Ltd | Real estate | 2016 |
| MHZ Ltd | Manufacturing | 2014 |
| MI Short Stay Ltd | Hospitality | 2022 |
| Micco Computing Limited | Information & communication | 2012 |
| Michelle Crowther Care Management Ltd | Public administration | 2025 |
| Micklebridge Limited | Real estate | 1986 |
| Micon Health Limited | Wholesale & retail | 2005 |
| Micro Materials Limited | Manufacturing | 1988 |
| Microdot Studio Ltd | Information & communication | 2025 |
| Microtech Precision Limited | Manufacturing | 1989 |
| MID Surrey Finance Company Limited | Real estate | 1957 |
| Midcap Limited | Professional & scientific | 2024 |
| Midcap Properties Limited | Real estate | 2025 |