| M.I.Y Aesthetics and Training Ltd | Other services | 2018 |
| M.V.R. Autos Ltd | Manufacturing | 2009 |
| M7 Homes Limited | Real estate | 2021 |
| MA Oakfield NW Ltd | Hospitality | 2024 |
| MA Properties (NW) Ltd | Real estate | 2025 |
| Ma&Ja Cafe Ltd | Hospitality | 2024 |
| Macadamia Hair Spa Ltd | Other services | 2012 |
| Macca Developments Limited | Construction | 2011 |
| Mackenzie Russell Ltd | Administrative & support | 2017 |
| Mackinlay Developments Ltd | Construction | 2025 |
| Maclean Productions Limited | Information & communication | 2024 |
| MAD Speed Customs Ltd | Wholesale & retail | 2025 |
| Magee's DRY Cleaners Ltd | Other services | 2023 |
| Magic HAT Limited | Information & communication | 2013 |
| Magna Electrical Contractors Ltd | Construction | 2021 |
| Magnolia Healthcare Limited | Health & social care | 2008 |
| Magnolia Properties Limited | Real estate | 2015 |
| Mainline Ceilings Limited | Construction | 2001 |
| Maintenance CK Ltd | Construction | 2014 |
| Maintenance Cleaning Services Limited | Administrative & support | 2001 |
| Maintenance Solutions (GB) Ltd | Manufacturing | 2006 |
| Maintenance Solutions (NW) Ltd | Manufacturing | 2013 |
| Maira Shop Studio Ltd | Wholesale & retail | 2023 |
| Malkin Enterprises Ltd | Other services | 2010 |
| Maltese Falcon Tiling Limited | Construction | 2025 |
| Mama Fish Bar Limited | Hospitality | 2015 |
| Mamamia (ZA) Limited | Hospitality | 2024 |
| Mamamia Widnes NH Limited | Hospitality | 2025 |
| Mammon Media Limited | Information & communication | 2025 |
| MAN With a Van Liverpool Ltd | Transport & logistics | 2025 |
| Manahil Ltd | Hospitality | 2025 |
| Manby's Property Developments Ltd | Construction | 2025 |
| Mango Living Ltd | Hospitality | 2025 |
| Manor Car Hire Limited | Administrative & support | 2008 |
| Manor Farm (Barnston) Limited | Real estate | 2019 |
| Manor Farm (Barnston) Management Company Limited | Real estate | 2022 |
| Manor Farm Court Residents Association Limited | Households | 1999 |
| Mantec Projects Limited | Construction | 2012 |
| MANUTRANSPORT2024 Ltd | Transport & logistics | 2024 |
| Many Events Food Ltd | Hospitality | 2019 |
| Maple Property & Lettings Limited | Real estate | 2026 |
| Mapple Properties Limited | Construction | 2023 |
| Marcal Engineering & Validation Services Ltd | Professional & scientific | 2017 |
| Marcu Profi Trans Ltd | Transport & logistics | 2018 |
| Marcusp Ltd | Wholesale & retail | 2021 |
| Marianka Trans Ltd | Transport & logistics | 2018 |
| MARIS85 Ltd | Transport & logistics | 2024 |
| Mark T Milson Ltd | Professional & scientific | 2012 |
| Mark'Ennovy Personalized Care Limited | Manufacturing | 2007 |
| Marksans Holdings Limited | Professional & scientific | 2005 |
| Marksans Pharma U.K. Limited | Professional & scientific | 2005 |
| Marleysbar Limited | Hospitality | 2026 |
| Marlowe One Ltd | Construction | 2025 |
| Marmalade Services (Cheshire) Ltd | Professional & scientific | 2021 |
| Marsh Pasture Limited | Hospitality | 2025 |
| Marshall Windows & Doors Ltd | Construction | 2024 |
| Marshalls Commercials Ltd | Wholesale & retail | 2024 |
| Marwell Psychology Limited | Education | 2024 |
| Mary's Food Widnes Ltd | Hospitality | 2024 |
| MAS Cheshire Limited | Construction | 2019 |
| MAS Services Northwest Ltd | Professional & scientific | 2025 |
| Mast Family Limited | Wholesale & retail | 2025 |
| Mastechuk Ltd | Construction | 2017 |
| Match My PA Ltd | Administrative & support | 2023 |
| Mattocks Grindley Ltd | Professional & scientific | 2010 |
| Maven Recruitment & Social Care Limited | Public administration | 2023 |
| MAW Engineering Services (Merseyside) Limited | Construction | 2014 |
| Mayer Goldman Consulting Ltd | Professional & scientific | 2019 |
| MB Holding North West Limited | Financial services | 2020 |
| Mccaffrey Mortgages Limited | Financial services | 2008 |
| Mccalmont Forster Ltd | Real estate | 2026 |
| Mccann & Sons Roofing Ltd | Construction | 2024 |
| Mccann Associates NW Ltd | Administrative & support | 2025 |
| Mccann Cafe and Bistro Ltd | Hospitality | 2023 |
| Mccormick Electrical Ltd. | Construction | 1999 |
| Mccr Holdings Limited | Other services | 2024 |
| Mcgillicuddy & Associates Ltd | Professional & scientific | 2019 |
| MCJ Nuclear Solutions Limited | Manufacturing | 2012 |
| MCM Management Services Ltd | Real estate | 2017 |
| MCN Services Widnes Ltd | Construction | 2024 |
| Mcparland Sports Management Limited | Administrative & support | 2018 |
| MCS Electrical Contracts Limited | Information & communication | 2012 |
| Mcuk Developments Limited | Construction | 2019 |
| Mcuk Fitouts Limited | Construction | 2015 |
| Mcuk Holdings NW Ltd | Financial services | 2025 |
| Mcuk Joinery Limited | Construction | 2023 |
| Mcuk Properties Limited | Real estate | 2022 |
| Mcuk Supplies Limited | Manufacturing | 2018 |
| MD Orrell Ltd | Hospitality | 2018 |
| MD Plastering Ltd | Construction | 2018 |
| Mdda Training Limited | Transport & logistics | 2019 |
| Meades Roofing Services (Widnes) Ltd | Construction | 2023 |
| Mealswithwheels Ltd | Hospitality | 2025 |
| MEB Driver Services Limited | Transport & logistics | 2014 |
| Mechanelec Limited | Administrative & support | 1978 |
| Mecon Ltd | Construction | 2015 |
| Medi-Gem Limited | Health & social care | 2022 |
| Medicinal Massage Ltd | Other services | 2025 |
| Melo Consultancy Limited | Administrative & support | 2019 |
| Melo Holdings Limited | Financial services | 2019 |