| M&A Formation Ltd | Hospitality | 2019 |
| M&D Sealants Ltd | Construction | 2022 |
| M&K (DOC) Limited | Health & social care | 2020 |
| M&M Controls Limited | Wholesale & retail | 2017 |
| M&Ms Construction Ltd | Construction | 2013 |
| M-Technical Services Ltd | Professional & scientific | 2023 |
| M. Brynes Transport Ltd | Transport & logistics | 2017 |
| M. Smith Brickwork and Construction Ltd | Construction | 2022 |
| M.A.S.Technology Ltd | Professional & scientific | 2003 |
| M.Dilaxy Chicken Ltd | Hospitality | 2024 |
| M.J. Fellows (Building Contractors) Limited | Construction | 2004 |
| M.T.S. Construction Hull Limited | Construction | 2010 |
| M1CONSULTANTS Limited | Construction | 2015 |
| M1NT Ltd | Information & communication | 2022 |
| MA Rainford Investments Limited | Information & communication | 2024 |
| MAC Construction Yorkshire Limited | Construction | 2025 |
| MAC Hospitality Limited | Hospitality | 2006 |
| MAC Tanwen Ltd | Other services | 2020 |
| Machine Tool Technologies (Holdings) Ltd | Financial services | 2025 |
| Machine Tool Technologies Limited | Manufacturing | 2001 |
| Macintosh Software Testing Ltd | Information & communication | 2011 |
| Mack 8 Ltd | Construction | 2024 |
| Mackinnon Shipping Ltd | Transport & logistics | 2018 |
| Mackrill Financial Management Limited | Financial services | 2003 |
| Maclaran Motors Limited | Wholesale & retail | 2016 |
| MAD Designer Stage International Ltd | Professional & scientific | 2011 |
| MAD Edgar Productions Limited | Arts & recreation | 2008 |
| Madalex Consulting Limited | Professional & scientific | 2014 |
| Madry Transport Limited | Transport & logistics | 2024 |
| Maghull Football Club CIC | Arts & recreation | 2025 |
| Magic Touch Spas (Manchester) Limited | Health & social care | 2023 |
| Magicmonk Limited | Information & communication | 2018 |
| Magill Photography Ltd | Professional & scientific | 2024 |
| Magistra Limited | Professional & scientific | 2014 |
| Magistra Training Solutions CIC | Education | 2019 |
| Magma Fire & Security Ltd | Administrative & support | 2019 |
| Magma Software Engineering Limited | Information & communication | 2021 |
| Magnifind Ltd | Administrative & support | 2020 |
| Magnitude Developments Ltd | Construction | 2021 |
| Magnum Building Services Ltd | Construction | 2018 |
| Magnus Capital Limited | Financial services | 2022 |
| Magowan Consulting Ltd | Professional & scientific | 2017 |
| Magrad Limited | Information & communication | 2003 |
| Mahon & Mahon Limited | Hospitality | 2019 |
| Maidens Ladieswear Ltd | Wholesale & retail | 2019 |
| Main Electrical Contractors Ltd | Manufacturing | 2016 |
| Main Engineering & Construction Limited | Construction | 2023 |
| Main Layer Ltd | Wholesale & retail | 2016 |
| Main Street Leisure Limited | Hospitality | 2022 |
| Maine Property Limited | Real estate | 2022 |
| Maine Wealth Ltd | Financial services | 2018 |
| Mainline Distribution Ltd | Wholesale & retail | 2018 |
| Maison Dynamics Cleaning Limited | Administrative & support | 2016 |
| Maison Mortgage Group Limited | Financial services | 2026 |
| Majestic Coffee Lounge Limited | Hospitality | 2025 |
| Majestical Cleans Limited | Administrative & support | 2021 |
| Majornet Limited | Real estate | 1999 |
| Majstor Holdings Limited | Financial services | 2023 |
| Make (NW) Limited | Real estate | 2022 |
| Make Developments Group Limited | Financial services | 2024 |
| Makeover Girl Re-Invent Yourself Ltd | Wholesale & retail | 2019 |
| Makinson Distribution Limited | Wholesale & retail | 2025 |
| MAKOS-1 Ltd | Wholesale & retail | 2014 |
| Malachite Installations Ltd | Construction | 2023 |
| Malcolm Holdings Limited | Professional & scientific | 2009 |
| Mallinson Holdings Limited | Financial services | 2018 |
| Malloy Limited | Professional & scientific | 2018 |
| Malone's & Jones Industries Ltd | Wholesale & retail | 2021 |
| Mama MIA Food 1 Ltd | Hospitality | 2026 |
| Mamba Ltd | Manufacturing | 2018 |
| Mancave Gentlemans Grooming Ltd | Other services | 2017 |
| Manchester Foods Limited | Wholesale & retail | 2019 |
| Manchester Refractory Co. (1982) Limited | Manufacturing | 1982 |
| Manchester Skills Training Centre Ltd | Administrative & support | 2022 |
| Mangetout Bar and Grill Limited | Hospitality | 2019 |
| Mango Salad Inns Limited | Hospitality | 2023 |
| Manifest and Move Ltd | Wholesale & retail | 2025 |
| Mann Fine Wine Ltd | Wholesale & retail | 2021 |
| Manning and Woods Limited | Construction | 2011 |
| Manny Horizon Limited | Health & social care | 2021 |
| Manock Consulting Limited | Information & communication | 2009 |
| Manor Croft (Management Company) Limited | Households | 2025 |
| Manor House Commercials Limited | Real estate | 2020 |
| Mansour Consulting Ltd | Information & communication | 2024 |
| Manstrad Limited | Wholesale & retail | 2013 |
| Maple Crest Property Ltd | Real estate | 2026 |
| Mapperley House Limited | Real estate | 2017 |
| Mapsj Investiments Ltd | Health & social care | 2012 |
| Marble Media - Digital Performance Ltd | Professional & scientific | 2020 |
| Marcus (MR Home Improvement) Ltd | Construction | 2015 |
| Marcus Horwich Limited | Hospitality | 2025 |
| Marcus Kinsman Limited | Professional & scientific | 2014 |
| Marcus Moore Catering Limited | Hospitality | 2001 |
| Mare Textile Ltd | Wholesale & retail | 2018 |
| Mariusz Duda Plastering Ltd | Construction | 2018 |
| Mark Booker Insights Ltd | Professional & scientific | 2021 |
| Mark Jensen Fitness Limited | Other services | 2018 |
| Mark Wakefield Demolition Ltd. | Construction | 2004 |
| Mark Wakefield Plant & Equipment Ltd | Administrative & support | 2014 |
| Mark-Ed Delivery Ltd | Transport & logistics | 2020 |