| Mark Harrington Builders Limited | Construction | 2019 |
| Mark Leese & SON Limited | Wholesale & retail | 2011 |
| Mark Lutitt Enterprise Ltd | Information & communication | 2025 |
| Mark Newton Piping Solutions Ltd | Manufacturing | 2015 |
| Mark Taylor Groundworks Limited | Construction | 2010 |
| Mark Walker Contracting Ltd | Construction | 2006 |
| Mark's Tyre Service Limited | Wholesale & retail | 2019 |
| Marker LAB Ltd | Professional & scientific | 2012 |
| Market Consultants Limited | Administrative & support | 2005 |
| Market Consulting Limited | Administrative & support | 2002 |
| Market Done Limited | Administrative & support | 2020 |
| Markhor Estate Ltd | Real estate | 2025 |
| Markreach Ltd | Professional & scientific | 2026 |
| Markrich Limited | Other services | 2012 |
| Marks 4 Training & Language Centre Ltd | Education | 2009 |
| Marks 4 Training Centre Community Interest Company | Education | 2009 |
| Marks Micros Limited | Wholesale & retail | 2017 |
| Marks Service Centre (MSC) Ltd | Wholesale & retail | 2011 |
| Marlison PUB Group Ltd | Hospitality | 2026 |
| Marmalade Ltd | Financial services | 2013 |
| Marmalade Network Ltd | Other services | 2016 |
| Marnie Global Auto Exports Ltd | Wholesale & retail | 2025 |
| Maroof Estates Ltd | Construction | 2025 |
| Marpen Property Agents Ltd | Real estate | 2025 |
| Marriott Contract Solutions Limited | Professional & scientific | 2010 |
| Marsden Music Limited | Education | 2003 |
| Marsh Developments (NW) Limited | Construction | 2014 |
| Marsh Head Cafe Limited | Hospitality | 2012 |
| Marshall Accountancy Ltd | Professional & scientific | 2015 |
| Marshallwood Property Ltd | Construction | 2025 |
| Marson Classic Cars Limited | Wholesale & retail | 2019 |
| Marston & Price Removals House Clearances & Storage Ltd | Transport & logistics | 2018 |
| Martial-Unit Management Services Limited | Administrative & support | 2009 |
| Martin Colour Company Limited | Manufacturing | 1940 |
| Martin Impey Limited | Extraterritorial | 2004 |
| Marvellous Learning Limited | Education | 2017 |
| Maryam Enterprise Stoke Ltd | Wholesale & retail | 2025 |
| Mashiak Cherub Group Limited | Education | 2025 |
| Mason & Thompson Limited | Hospitality | 2017 |
| Masons Right Price Carpets & Beds Limited | Wholesale & retail | 2017 |
| Mass Businesses Ltd | Wholesale & retail | 2024 |
| Massey Business Solutions Limited | Professional & scientific | 2013 |
| Master Grill Tunstall Ltd | Hospitality | 2025 |
| Master GS and Sons Limited | Wholesale & retail | 2025 |
| Master Tyres & Tracking Ltd | Wholesale & retail | 2025 |
| Mastercarr Limited | Professional & scientific | 2005 |
| Mastering Mamahood Ltd | Professional & scientific | 2025 |
| Matara Katagasma Spicy Kitchen Limited | Manufacturing | 2026 |
| Matco Denham Limited | Wholesale & retail | 2026 |
| Matharu Medical Services Ltd | Health & social care | 2020 |
| Mathi Trading Elite Ltd | Wholesale & retail | 2025 |
| Mathi Trading Ltd | Wholesale & retail | 2023 |
| Mathi UK Trading Ltd | Wholesale & retail | 2025 |
| Mathruma Ltd | Wholesale & retail | 2026 |
| Maticcam Limited | Information & communication | 2024 |
| Matrix Credit Limited | Financial services | 2000 |
| Matsense AI Limited | Information & communication | 2025 |
| Matt Colours Limited | Construction | 2014 |
| Matt Dental Ltd | Extraterritorial | 2021 |
| Matt Gardner Electrical Ltd | Construction | 2022 |
| Matthew Baddeley Property Limited | Real estate | 2024 |
| Matthew Broadgate Ltd | Wholesale & retail | 2023 |
| Matthew Costello Services Limited | Transport & logistics | 2018 |
| Matthew James Stevenson Limited | Extraterritorial | 2025 |
| Matthews & SON (Hanley) Limited | Manufacturing | 1981 |
| Matthews Engineering (Stoke) Limited | Manufacturing | 2003 |
| Mava Trading Limited | Wholesale & retail | 2026 |
| Maverick Boxing Limited | Arts & recreation | 2021 |
| Maverick Dog Training Ltd | Other services | 2026 |
| Maverick Living Ltd | Real estate | 2026 |
| MAW Control Services Limited | Manufacturing | 2006 |
| Mawgans Food Delivery Ltd | Transport & logistics | 2026 |
| MAX Yield Deals Ltd | Wholesale & retail | 2025 |
| MAX1MUS Ltd | Arts & recreation | 2019 |
| Maxcare Trading Removals Ltd | Wholesale & retail | 2024 |
| Maxguard Security Ltd | Administrative & support | 2024 |
| Maxhealth Limited | Health & social care | 2014 |
| Maxi Cura Limited | Extraterritorial | 2017 |
| Maximum Care UK Limited | Professional & scientific | 2008 |
| Maximum Performance Sports & Physio Therapy Ltd | Health & social care | 2024 |
| Maximum Performance Sports Therapy Ltd | Health & social care | 2020 |
| Maxlife Care Ltd | Administrative & support | 2023 |
| Maxpro Products Ltd | Wholesale & retail | 2025 |
| Maxwell Software Ltd | Information & communication | 2013 |
| Maxy Food Limited | Hospitality | 2025 |
| Mayas Lounge Ltd | Hospitality | 2024 |
| Mayer Aggregates and Recycling Limited | Water & waste | 2021 |
| Mayer Plant Hire Limited | Administrative & support | 2021 |
| Mayer Plant Limited | Administrative & support | 2021 |
| Mayer Plant Sales Limited | Wholesale & retail | 2021 |
| Mayer UK Group Limited | Financial services | 2022 |
| Mayfair Cleaners Ltd | Other services | 2025 |
| Mayflower Horizon Limited | Information & communication | 2023 |
| Mayneline Electrical and Security Ltd | Construction | 2022 |
| Mayomi Healthcare Ltd | Health & social care | 2023 |
| Mayplus Care Solutions Ltd | Health & social care | 2015 |
| MAZ & GAZ Ltd | Wholesale & retail | 2022 |
| MAZ Painters Limited | Construction | 2025 |
| MAZ Properties Stoke Ltd | Real estate | 2025 |
| Mazac Properties Limited | Real estate | 2022 |