| Matthew Britcliffe & Company Limited | Professional & scientific | 2021 |
| MAX Car Trader Ltd | Wholesale & retail | 2025 |
| Maxiled Lighting UK Limited | Manufacturing | 2025 |
| Maximf Investments Limited | Real estate | 2020 |
| Maximf Limited | Health & social care | 2019 |
| Maxksmum Holdings Ltd | Financial services | 2026 |
| Maysons Solicitors Ltd | Professional & scientific | 2013 |
| MB Line Ltd | Financial services | 2014 |
| MB Property Ventures Ltd | Real estate | 2026 |
| Mbcd Ltd | Professional & scientific | 2023 |
| MBD Assist Limited | Transport & logistics | 2024 |
| MBD Sofas Limited | Manufacturing | 2023 |
| MC Start C.I.C. | Health & social care | 2025 |
| MCC Property Partners Ltd | Real estate | 2025 |
| Mccully Properties Ltd | Construction | 2020 |
| Mcdevitt Controls Ltd | Manufacturing | 2017 |
| Mcdevitt Electrical & Controls Limited | Construction | 2015 |
| Mcdevitt International Security Services Ltd | Other services | 2022 |
| MCE Windows & Doors Ltd | Manufacturing | 2013 |
| Mcgowan Media Ltd | Information & communication | 2018 |
| MCK Contract Services Ltd | Professional & scientific | 2016 |
| MCL Consulting Partners Ltd | Administrative & support | 2025 |
| MCR Car Mart Ltd | Wholesale & retail | 2024 |
| MCR Management Group Ltd | Real estate | 2026 |
| Mcsherrys Limited | Wholesale & retail | 2025 |
| MCV Aesthetics Ltd | Other services | 2021 |
| Mcwalshe Limited | Construction | 2002 |
| Mdcarier Ltd | Manufacturing | 2024 |
| MDM Facilities Management Limited | Administrative & support | 2026 |
| MDP NE29 Ltd | Financial services | 2024 |
| MDW Electrical Ltd | Construction | 2026 |
| Meadow Drives and Patios Limited | Construction | 2016 |
| Meadow View (Read) Management Company Limited | Households | 2014 |
| Meadowlark Homes Ltd | Real estate | 2019 |
| Meat Into Europe (2001) Limited | Other services | 2001 |
| Meco Homes Ltd | Administrative & support | 2020 |
| Media Design and Print Ltd | Manufacturing | 2024 |
| Media Diverse Limited | Information & communication | 2006 |
| Media Junkie (London) Limited | Professional & scientific | 2015 |
| Medilink PTS Limited | Transport & logistics | 2025 |
| Medinor Ltd | Health & social care | 2017 |
| Mediterranean Linens Limited | Wholesale & retail | 2008 |
| Medivision Diagnostics Ltd | Real estate | 2012 |
| Megafirm Limited | Wholesale & retail | 2025 |
| Megahertz Medical Limited | Health & social care | 2019 |
| Megmoo Limited | Wholesale & retail | 2017 |
| MEH Marketing Ltd | Other services | 2017 |
| Mehrish Services Limited | Real estate | 2011 |
| MEI PO House Burnley Ltd | Hospitality | 2025 |
| MEL Construction Limited | Construction | 2009 |
| MEL Metalica Engineering Limited | Manufacturing | 2024 |
| Melcroft Care Ltd | Health & social care | 2025 |
| Melissa House Limited | Extraterritorial | 2026 |
| Melpass Limited | Extraterritorial | 2001 |
| Menzolit Ltd. | Manufacturing | 1987 |
| MEP Site Services Ltd | Construction | 2018 |
| Merc Aerospace Holdings Limited | Financial services | 2022 |
| Merc Aerospace Limited | Professional & scientific | 1970 |
| Merc Group Limited | Extraterritorial | 2008 |
| Mercenary Athletics Ltd | Wholesale & retail | 2020 |
| Merge-Tech Ltd | Professional & scientific | 2020 |
| Metandu Inc Ltd | Administrative & support | 2018 |
| Metcalfe Aerotech Limited | Manufacturing | 2021 |
| Metcalfe's Window Cleaning Services Ltd | Other services | 2020 |
| Metconnect Ltd | Construction | 2004 |
| Methode Electronics UK Limited | Administrative & support | 2008 |
| MFS (NW) Ltd | Construction | 2009 |
| MG Beauty Incorporated Ltd | Other services | 2018 |
| MG Vehicle Services Ltd | Wholesale & retail | 2022 |
| MGM Systems Ltd | Construction | 2015 |
| MGS Heating Solutions Ltd | Construction | 2021 |
| MH Pro Property Ltd | Real estate | 2026 |
| MH Secure & Services Limited | Transport & logistics | 2025 |
| MHE Hauliers Limited | Transport & logistics | 2019 |
| Mhec Properties Ltd | Real estate | 2020 |
| MHQ Trading Limited | Wholesale & retail | 2013 |
| Miah's Properties & Maintenance Ltd | Real estate | 2021 |
| Mian&Sons Limited | Hospitality | 2025 |
| Mica Trading (North West) Limited | Real estate | 2010 |
| Michael Bramich Ltd | Information & communication | 2015 |
| Michael Duane Reproductions Ltd | Manufacturing | 2003 |
| Micris Limited | Manufacturing | 1999 |
| Microwave Oven Service Limited | Manufacturing | 1986 |
| MID Cheshire Flooring Limited | Wholesale & retail | 2019 |
| MID Pennine Arts | Arts & recreation | 2011 |
| Midland Investment Castings Limited | Manufacturing | 2007 |
| Midlands Telecom Holdings 1 Limited | Information & communication | 2017 |
| Midnight Flames Ltd | Hospitality | 2025 |
| MIJ Holdings Ltd | Real estate | 2019 |
| Mike Phelan Coaching Limited | Education | 2024 |
| Mikropor UK Limited | Wholesale & retail | 2023 |
| Milestone London Limited | Households | 1999 |
| Mill Antiques and Salvage Limited | Administrative & support | 2019 |
| Mill Storage Ltd | Other services | 2022 |
| Mill Street Investments (NW) Limited | Real estate | 2022 |
| Mill Street Property Investment Ltd | Real estate | 2022 |
| Mill Town Inspection Ltd | Professional & scientific | 2026 |
| Millennium Takeaway Ltd | Hospitality | 2024 |
| Mills and Hills (Events and Promotions) Ltd | Arts & recreation | 2026 |
| Mills and Hills Consultancy Ltd | Professional & scientific | 2023 |