| Mcintyre & Weston Limited | Real estate | 1983 |
| Mckay Ventures Limited | Real estate | 2022 |
| Mcmillan & Kelly Ltd | Professional & scientific | 2023 |
| Mcmillan (York) Limited | Wholesale & retail | 1994 |
| Mcmillan and Associates Ltd | Administrative & support | 2018 |
| Mcmurray GIN Ltd | Wholesale & retail | 2026 |
| Mcmurtrie Limited | Professional & scientific | 2004 |
| Mcneil Beechey O'Neill Architects LLP | | 2001 |
| MCO Accountancy Ltd | Professional & scientific | 2018 |
| Mcoo Ltd | Real estate | 1996 |
| Mcr:Music Limited | Information & communication | 2004 |
| MCS Executive Search Limited | Administrative & support | 2012 |
| MCS North Yorks Ltd | Administrative & support | 2026 |
| MCT Yorkshire Limited | Administrative & support | 2019 |
| Mcwpl Limited | Administrative & support | 2012 |
| MD Cleckheaton Limited | Health & social care | 2019 |
| MD Doncaster Limited | Health & social care | 2022 |
| MD Hotels Ltd | Hospitality | 2025 |
| MD Normanton Limited | Health & social care | 2015 |
| MDB Associates Limited | Manufacturing | 2002 |
| Mddoubleu Limited | Professional & scientific | 2016 |
| MDE Associates LLP | | 2007 |
| MDL Installations Ltd | Construction | 2019 |
| MDM Business Ltd | Professional & scientific | 2026 |
| MDO Engineering Ltd | Manufacturing | 2014 |
| MDR Consultancy Limited | Professional & scientific | 2013 |
| ME Electricals (Yorkshire) Limited | Construction | 2017 |
| ME FG Properties Ltd | Real estate | 2019 |
| ME. Aesthetics York Ltd | Other services | 2024 |
| Meadow and Oak Ltd | Education | 2025 |
| Meadow Rise (Scorton) Management Company Limited | Households | 2026 |
| Meadow View Track Livery Ltd | Agriculture & fishing | 2023 |
| Meadowcrofts Laundry and DRY Cleaners Limited | Other services | 2022 |
| Meadowside Developments Limited | Construction | 1999 |
| Meanwood Park Management Company Limited | Households | 2001 |
| Mearas AI Ltd | Information & communication | 2026 |
| Meatlinc Sheep Co. Limited(The) | Agriculture & fishing | 1977 |
| Medactec Consulting Limited | Professional & scientific | 2014 |
| Medd Construction Limited | Construction | 2021 |
| Medd Motors Ltd | Wholesale & retail | 2014 |
| Meddyg Ltd | Health & social care | 2024 |
| Medhut Clinic Ltd | Wholesale & retail | 2021 |
| Median Consulting Group Ltd | Information & communication | 2023 |
| Medical CSM Solutions Ltd | Professional & scientific | 2022 |
| Medicall Recruitment Limited | Administrative & support | 2018 |
| Medico-Crystal Aesthetics Limited | Other services | 2026 |
| Medicsensors Limited | Professional & scientific | 2016 |
| Mediduct Limited | Manufacturing | 2024 |
| Mediterranean Luxury Foods Limited | Wholesale & retail | 2015 |
| Meditest Limited | Education | 2025 |
| Medlock & Langley Limited | Professional & scientific | 2025 |
| Medlock Partners Limited | Administrative & support | 2021 |
| Medtec Talent Limited | Extraterritorial | 2019 |
| Meenavision Limited | Health & social care | 2013 |
| Megabot Ltd | Information & communication | 2004 |
| Megalab.Net Limited | Extraterritorial | 1976 |
| Megdale Limited | Real estate | 2019 |
| Mehmet Polat Ltd | Hospitality | 2026 |
| Melbourne Arms York Limited | Hospitality | 2025 |
| Mellfield Consultancies Limited | Other services | 2008 |
| Mellifera One Consulting Limited | Professional & scientific | 2021 |
| Melodie Park Limited | Hospitality | 2003 |
| Melphi Enterprises Limited | Administrative & support | 2006 |
| Melric Property Power Ltd | Administrative & support | 2025 |
| Melrose Mortgages Limited | Financial services | 2022 |
| Melrose Pigs Limited | Agriculture & fishing | 2011 |
| Melross Limited | Financial services | 2024 |
| Melton College Ltd | Education | 2006 |
| Melton Language Services Limited | Financial services | 2019 |
| Meltx Limited | Professional & scientific | 2021 |
| Melville Homes Limited | Professional & scientific | 1986 |
| MEN in White Limos Limited | Transport & logistics | 2017 |
| Menagerie House Ltd | Hospitality | 2022 |
| Menchies Filipino Kitchen Ltd | Wholesale & retail | 2025 |
| Mend Building Limited | Construction | 2021 |
| Menopause Plan Ltd | Health & social care | 2025 |
| Mentorre Limited | Information & communication | 2024 |
| Meplas Ltd | Water & waste | 2018 |
| Meralo Properties Limited | Real estate | 2021 |
| Mercer Construction & Groundworks Limited | Construction | 2019 |
| Mercer Management (UK) Limited | Other services | 2007 |
| Mercer Parkin Builders Limited | Construction | 2008 |
| Mercer Ritchie Ltd | Administrative & support | 2008 |
| Mercers Foods Ltd | Wholesale & retail | 2007 |
| Mercers Furniture Limited | Wholesale & retail | 2010 |
| Merchantgate Developments Limited | Real estate | 2025 |
| Merchants Place York Management Company Limited | Hospitality | 2014 |
| Merchants Walk Cullompton NO 2 Management Company Limited | Households | 2011 |
| Mercurious Technology Ltd | Information & communication | 2020 |
| Merefolk Ltd | Wholesale & retail | 2026 |
| Merewood (Kendal) Limited | Extraterritorial | 1992 |
| Merewood Group Limited | Construction | 1985 |
| Merewood Homes Limited | Extraterritorial | 1995 |
| Merewood Investments Limited | Professional & scientific | 1987 |
| Merida Holdings Limited | Financial services | 2026 |
| Meridian Coachworks Limited | Wholesale & retail | 2008 |
| Meridian Veterinary Practice Limited | Professional & scientific | 2001 |
| Merino Properties (York) Limited | Real estate | 2013 |
| Merisis Ltd | Information & communication | 2003 |
| Merisis Technology Limited | Information & communication | 2005 |