| Mainprize Wilson Ltd | Real estate | 2022 |
| Maisie Days Limited | Health & social care | 2012 |
| MAJ Building & Engineering Services Limited | Professional & scientific | 2009 |
| Majenta Building Services Ltd | Construction | 2023 |
| Majestic Country Parks Ltd | Hospitality | 2020 |
| Majestic Farm Estates Limited | Professional & scientific | 2023 |
| Majg Limited | Construction | 2012 |
| Make Believe UK Limited | Professional & scientific | 2005 |
| Make IT York Limited | Other services | 2014 |
| Make the World Wild Ltd | Agriculture & fishing | 2020 |
| Make Your Mark Rubber Stamps Limited | Manufacturing | 2003 |
| Makey and Sons Ltd | Professional & scientific | 2026 |
| Makkah International Foods York Ltd | Wholesale & retail | 2026 |
| Makondo Limited | Real estate | 2023 |
| Makotapharma Ltd | Wholesale & retail | 2022 |
| Maks Foods Ltd | Hospitality | 2026 |
| Maks Takeaway Ltd | Hospitality | 2017 |
| Malarkey Paving Limited | Construction | 2024 |
| Mali Barbers Limited | Other services | 2019 |
| Mallard Construction Ltd | Construction | 2025 |
| Mallard Residential Limited | Real estate | 2001 |
| Mallory Consulting Limited | Professional & scientific | 2025 |
| Maloney Logistics Services Ltd | Transport & logistics | 2025 |
| Malt Kiln Medical Ltd | Health & social care | 2015 |
| Malthouse Meadows (West Sompting) Residents Management Company Limited | Households | 2024 |
| Maltings Farm (Agriculture) Limited | Other services | 1981 |
| Malton & Pickering Flat Roofing Limited | Construction | 2024 |
| Malton Commercials Limited | Other services | 2014 |
| Malton Community Sports Centre Limited | Education | 2024 |
| Malton Grange Lodges Ltd | Hospitality | 2016 |
| Malton Hot Foods Ltd. | Hospitality | 2022 |
| Malton Marquees Limited | Administrative & support | 2005 |
| Malton Motor Club Limited | Administrative & support | 2003 |
| Maluda Limited | Energy | 2014 |
| Malvern Rise (Malvern) Management Company Limited | Households | 2020 |
| Mama Rise Limited | Hospitality | 2025 |
| Mambasnake Ltd | Wholesale & retail | 2022 |
| Mamma MIA York Ltd | Hospitality | 2026 |
| Mammamia's (York) Ltd | Hospitality | 2000 |
| MAN Properties Ltd | Administrative & support | 2001 |
| Mana Civils & Utilities Ltd | Construction | 2020 |
| Manacure Ltd | Manufacturing | 2024 |
| Managed Consultancy Services Group Limited | Administrative & support | 2021 |
| Manaj Places Ltd | Real estate | 2002 |
| Manchester Square Security Limited | Real estate | 2019 |
| Manco Energy Limited | Wholesale & retail | 2003 |
| Manco Pellets Limited | Wholesale & retail | 2003 |
| Mandalay Consulting Limited | Wholesale & retail | 2021 |
| Mandria Properties 1 Ltd | Real estate | 2024 |
| Mandria Properties Ltd | Real estate | 2023 |
| Mandrolsai Limited | Hospitality | 2025 |
| Mango Store Ltd | Wholesale & retail | 2012 |
| Manhley Takeaway Limited | Hospitality | 2021 |
| Manicom Construction Limited | Construction | 2018 |
| Manifestly Important Ltd | Professional & scientific | 2022 |
| Mannetti's Limited | Hospitality | 2019 |
| Manor Court Management Company (Sutton on Forest) Limited | Real estate | 2019 |
| Manor Drive Freehold Limited | Real estate | 2011 |
| Manor Farm (Huntington) Management Company Limited | Households | 2014 |
| Manor Farm (Micklefield) Management Company Limited | Households | 2019 |
| Manor Farm 1 Limited | Real estate | 2025 |
| Manor Farm Yearsley LLP | | 2016 |
| Manor Gardens (Selsey) Management Company Limited | Households | 2022 |
| Manor Park (Malton) Limited | Financial services | 2019 |
| Manor Park (Scarborough) Limited | Construction | 2025 |
| Manor Place (Maidenhead) Residents Management Company Limited | Households | 2016 |
| Manor Smiles Ltd | Health & social care | 2015 |
| Manorscene Limited | Mining & quarrying | 2014 |
| Mansion Gates Management Company Limited | Real estate | 2019 |
| Manskip Hygiene Services Ltd. | Administrative & support | 2026 |
| Mantadeck Ltd | Manufacturing | 2020 |
| Manterra Limited | Agriculture & fishing | 2011 |
| Manuel Ceconi Limited | Health & social care | 2014 |
| Many Two One Limited | Other services | 2021 |
| Manytones Event Management Ltd | Administrative & support | 2022 |
| MAP Data Engineering Ltd | Information & communication | 2024 |
| Mapio Financial Limited | Financial services | 2019 |
| Maple Lane Huby Management Company Limited | Households | 2024 |
| Maple Logic Ltd | Information & communication | 2024 |
| Maple Wood Manco (Church Fenton) Limited | Real estate | 2024 |
| Maplegarth Ltd | Professional & scientific | 2024 |
| Mapleleigh Limited | Extraterritorial | 1989 |
| Mar-Co Digital Limited | Professional & scientific | 2025 |
| Marazion Developments Limited | Construction | 2006 |
| Marbella Private Office Limited | Real estate | 2009 |
| Marble JAR Limited | Manufacturing | 2025 |
| Marc Oliver Bathrooms Kitchens and Tiles Ltd | Wholesale & retail | 2026 |
| Marc Oliver Bathrooms Limited | Wholesale & retail | 2009 |
| Marc Oliver Kitchens Limited | Wholesale & retail | 2017 |
| Marc Oliver Tiles Limited | Wholesale & retail | 2013 |
| Marcal Ltd | Transport & logistics | 2022 |
| Marche Holiday Homes Limited | Real estate | 2004 |
| Marcheur Commercial Limited | Administrative & support | 2026 |
| Marchi Properties Limited | Other services | 2022 |
| Marching on Together Ltd | Professional & scientific | 2019 |
| Marcia O'Dea Design Co. Ltd | Professional & scientific | 2013 |
| Marcon Gamestock Limited | Agriculture & fishing | 1981 |
| Marekghousing Ltd | Real estate | 2025 |
| Mareverde Limited | Professional & scientific | 2024 |
| Marframe Limited | Professional & scientific | 2010 |