| Markac Ltd. | Transport & logistics | 2021 |
| Markapture Limited | Information & communication | 2023 |
| Market Value Properties Limited | Households | 2012 |
| Marketezeai Ltd | Information & communication | 2025 |
| Markham Grange Garden Centre Ltd | Agriculture & fishing | 2021 |
| Markos Commercial Limited | Manufacturing | 2000 |
| Markos Group Ltd | Financial services | 2014 |
| Marlaw Developments Ltd | Construction | 2020 |
| Marmaris Barber Club Ltd | Other services | 2025 |
| Marplace (Number 641) Limited | Financial services | 2004 |
| Marple Farming Limited | Agriculture & fishing | 2016 |
| Marq One Development Services Ltd | Professional & scientific | 2020 |
| Marquis Logistics Solutions Ltd. | Transport & logistics | 2017 |
| Marr's Bar & Grill Limited | Hospitality | 2022 |
| Marsaoui Real Estate Limited | Real estate | 2023 |
| Marshmo Properties Ltd | Real estate | 2021 |
| Marteque Design Services Limited | Professional & scientific | 2003 |
| Martin Clarke (Engineering Consultants) Limited | Professional & scientific | 2012 |
| Martin Freight Limited | Transport & logistics | 2014 |
| Martin Thompson Transport Ltd | Transport & logistics | 2025 |
| Martin Winstanley Joinery & Conservatories Ltd | Construction | 2017 |
| Martyn Ellis Limited | Wholesale & retail | 2003 |
| Marvel at Everything Limited | Professional & scientific | 2014 |
| MAS Medical Services Limited | Health & social care | 2015 |
| Mas-Security Ltd | Construction | 2020 |
| Masala Gallery Limited | Hospitality | 2019 |
| Mason Legal Consultancy Limited | Professional & scientific | 2024 |
| Mass Courier Service Ltd | Transport & logistics | 2024 |
| MASSA4HEAT Ltd | Construction | 2023 |
| Massala Indian Takeaway Chorley Ltd | Hospitality | 2019 |
| Mastan & Co Ltd | Real estate | 2005 |
| Master Tyres Chorley Ltd | Manufacturing | 2018 |
| Master Tyres Shop Chorley Ltd | Wholesale & retail | 2024 |
| Mastrad Furniture Components Limited | Wholesale & retail | 2021 |
| MAT SAV Transport Limited | Transport & logistics | 2021 |
| MAT Systems Limited | Information & communication | 1995 |
| MAT White Financial Services Limited | Financial services | 2015 |
| Matangi Expeditions and Consultancy Ltd | Education | 2026 |
| Matlo Properties Limited | Real estate | 2012 |
| Matolex Ltd | Information & communication | 2023 |
| Matrac Properties Limited | Real estate | 2003 |
| Matrix Corporate (Services) Ltd | Administrative & support | 2014 |
| Matrix Dental Laboratory Limited | Health & social care | 2003 |
| Matrix Developments (Lancashire) Limited | Construction | 2016 |
| Matrix DL Group Limited | Health & social care | 2020 |
| Matrix Park Properties LLP | | 2007 |
| Matrix Power Limited | Construction | 2010 |
| Matrix Properties Lancashire Limited | Real estate | 2018 |
| Matt Jones Film House Ltd | Information & communication | 2026 |
| Matt Watkinson Racing Limited | Arts & recreation | 2016 |
| Matt.K Driving Ltd | Transport & logistics | 2020 |
| Matthews GAS Services Ltd | Construction | 2019 |
| Mattlla Limited | Construction | 2021 |
| Mattlla Properties Limited | Construction | 2026 |
| Maunsel Limited | Hospitality | 2019 |
| Maverick Metalwork Ltd | Manufacturing | 2022 |
| MAX Equipment Hire Limited | Administrative & support | 2025 |
| Max's Pizza Nottingham Limited | Hospitality | 2019 |
| Maxfleet Limited | Transport & logistics | 2025 |
| Maxflo Pools Service & Maintenance Ltd | Extraterritorial | 2017 |
| Maxi-Grip Surfacing Limited | Construction | 2003 |
| Maxwell Manor Ltd | Professional & scientific | 2024 |
| MAY J Properties Ltd | Real estate | 2022 |
| Mayfair Solar Limited | Administrative & support | 2025 |
| Mayla Limited | Health & social care | 2022 |
| Maze Construction Ltd | Construction | 2009 |
| Maze Street Electrical Company Limited | Construction | 2019 |
| Mbcl Sped Ltd | Transport & logistics | 2024 |
| MBK Civils Limited | Construction | 2019 |
| MBL Partnership Limited | Financial services | 2025 |
| MBM Display & Digital Ltd | Manufacturing | 2014 |
| MBS (Stoneworks) Limited | Construction | 2007 |
| Mcatee Waterproofing Ltd | Construction | 2020 |
| Mcaweneys Limited | Hospitality | 2026 |
| Mcbuild Ltd | Construction | 2015 |
| MCC Direct Ltd | Administrative & support | 2021 |
| Mccabe Motors Limited | Wholesale & retail | 2013 |
| Mcclelland Media Ltd | Information & communication | 2004 |
| Mccrae Building Solutions Limited | Construction | 2025 |
| Mcfield Residential Limited | Real estate | 2018 |
| Mcgechie Ltd | Extraterritorial | 2013 |
| Mcgregors Wealth Management Limited | Extraterritorial | 2009 |
| Mcguinness Consultancy Limited | Professional & scientific | 2015 |
| Mchale Baker Ltd | Other services | 2011 |
| Mckeating Medical & Aesthetics Ltd | Health & social care | 2014 |
| Mckeever Consultancy Limited | Extraterritorial | 2021 |
| Mckeever Group Limited | Other services | 2016 |
| Mckeever Marketing Limited | Extraterritorial | 2021 |
| MCL Management Solutions Ltd | Professional & scientific | 2020 |
| MCM Business Consultancy Ltd | Administrative & support | 2011 |
| MCM UK Media Ltd | Professional & scientific | 2021 |
| Mcmillan & Co Consultants Limited | Professional & scientific | 1999 |
| Mcmillan & Co LLP | | 2009 |
| Mcmillan & Co Trustees Limited | Professional & scientific | 1998 |
| Mcphail Holdings Limited | Financial services | 2023 |
| Mcphail Property Limited | Real estate | 2023 |
| MCR Property Investments Ltd | Real estate | 2016 |
| MCW Compliance Ltd | Professional & scientific | 2023 |
| MD2 Holdings Ltd | Financial services | 2024 |
| MD2 Manufacturing Ltd | Wholesale & retail | 2017 |