| Mandarin Delight Limited | Hospitality | 2022 |
| Manderley Rosa Ltd | Wholesale & retail | 2022 |
| Manevo Ltd | Wholesale & retail | 2022 |
| Manfredis Exclusive Sneakers Limited | Wholesale & retail | 2022 |
| Manhise Ltd | Transport & logistics | 2024 |
| Mani Consult Ltd | Other services | 2023 |
| Manluk Ltd | Construction | 2025 |
| Manop Group Ltd | Professional & scientific | 2019 |
| Manor Barn (Kimberworth) Ltd | Hospitality | 2021 |
| Manor Farm Commercial Property Limited | Real estate | 2019 |
| Manor Farm Holdings Limited | Financial services | 2015 |
| Manor Farm Sausage Co Ltd | Extraterritorial | 2007 |
| Manor Rise Management Company Limited | Households | 2021 |
| Manor View Apartments Limited | Households | 2006 |
| Mansa Investing Ltd | Wholesale & retail | 2025 |
| Mansgate Restoration Ltd | Mining & quarrying | 2026 |
| Mansouri Cure Ltd | Health & social care | 2021 |
| Mantech Limited | Professional & scientific | 2023 |
| Manufacture & Maintenance Solutions Ltd | Professional & scientific | 2024 |
| Manvers Lake and Dearne Valley Events Limited | Arts & recreation | 2012 |
| Manvers Lake and Dearne Valley Trading Limited | Hospitality | 2012 |
| Manvers Lake and Dearne Valley Trust Limited | Arts & recreation | 2011 |
| Manvers Main Civil Engineering Limited | Administrative & support | 2025 |
| Manvers Main Construction Limited | Construction | 2023 |
| Manvers Main Contracts Limited | Professional & scientific | 2026 |
| Manvers Motor Spares Ltd | Wholesale & retail | 2014 |
| Manvers Waterfront Boat Club Limited | Arts & recreation | 2012 |
| MAP Services (Yorkshire) LLP | | 2022 |
| Maple Village Limited | Real estate | 2012 |
| Mapplewell Management Company Limited | Real estate | 2016 |
| MAR931 Trans Ltd | Transport & logistics | 2020 |
| Marasli Market Ltd | Wholesale & retail | 2021 |
| Marauder Events Ltd | Arts & recreation | 2022 |
| Marcopaulo's Limited | Hospitality | 2016 |
| Margas Heating and Plumbing Limited | Construction | 2015 |
| Margcare Ltd | Health & social care | 2025 |
| MARIA05 Limited | Wholesale & retail | 2020 |
| Mariard Developments Limited | Real estate | 2011 |
| Mariemont Construction Limited | Construction | 2026 |
| Marina Catering Ltd | Hospitality | 2014 |
| Marine GAS Supplies Limited | Wholesale & retail | 2023 |
| Marine Sealing Services Limited | Wholesale & retail | 1996 |
| Mark Hatfield Associates Ltd | Construction | 2022 |
| Mark Hudson (Estimating) Limited | Construction | 2006 |
| Mark Smith Tsco Services Limited | Other services | 2019 |
| Marli Group Ltd | Wholesale & retail | 2024 |
| Marlyn Property Developments Limited | Real estate | 2021 |
| Marlyn Roofing Limited | Construction | 2008 |
| Marma Services Ltd | Manufacturing | 2016 |
| Marmaris Barber S66 Ltd | Other services | 2024 |
| Marples & Co Property Ltd | Real estate | 2025 |
| Marsden Property Management Limited | Real estate | 2007 |
| Marsden Weighing Machine Group Limited | Manufacturing | 1971 |
| Marseb Kitchen Ltd | Hospitality | 2024 |
| Marsh Engineering (Killamarsh) Ltd | Manufacturing | 2014 |
| Marshalls Cosmetic Machines Ltd | Administrative & support | 2016 |
| Marshytv Limited | Information & communication | 2023 |
| Marsland Travel Ltd | Transport & logistics | 2013 |
| Marson Joinery & Shopfitting Limited | Construction | 2018 |
| Martek Holdings Limited | Professional & scientific | 2000 |
| Martek Marine Limited | Manufacturing | 2000 |
| Martin Brook Electrical Limited | Manufacturing | 2010 |
| Martin's Blinds & Shutters Ltd | Wholesale & retail | 2019 |
| Martract Limited | Other services | 1978 |
| Maru X Solutions Ltd | Wholesale & retail | 2025 |
| Maruti Tech Services Limited | Information & communication | 2023 |
| Marwah and Co Limited | Real estate | 2024 |
| Maryana Pizza Ltd | Hospitality | 2019 |
| Marybernie Properties Ltd | Real estate | 2023 |
| Marzenie Ltd | Wholesale & retail | 2022 |
| Marzipan Properties Ltd | Real estate | 2024 |
| MAS Business Consulting Limited | Professional & scientific | 2024 |
| Mash Cafe Limited | Hospitality | 2024 |
| Mash Haulage Ltd | Wholesale & retail | 2026 |
| Masif Delivery Service Ltd | Transport & logistics | 2024 |
| Mason & Hall Digital Ltd | Administrative & support | 2026 |
| Mason One Ltd | Hospitality | 2025 |
| Masscommrail Ltd | Information & communication | 2016 |
| Massimo Pizza Limited | Hospitality | 2019 |
| Massimo Pizza Yorkshire Limited | Hospitality | 2025 |
| Mast Cabinets Ltd | Manufacturing | 2025 |
| Master Blends Barber Shop Limited | Other services | 2021 |
| Master Fence Installation Ltd | Construction | 2019 |
| Masterfix Products U.K. Ltd | Extraterritorial | 1998 |
| Masterfix UK Holdings Limited | Extraterritorial | 1997 |
| Masterful Phrases Ltd | Wholesale & retail | 2015 |
| Mastermix Music Limited | Information & communication | 1994 |
| Mat-Trans International Ltd | Transport & logistics | 2024 |
| Matches Technology Ltd | Wholesale & retail | 2025 |
| Mateen Minimarket Limited | Wholesale & retail | 2024 |
| Mathias Enterprises Ltd | Wholesale & retail | 2024 |
| Maths and Dyscalculia Solutions Ltd | Education | 2022 |
| Matki Chai Group Ltd | Hospitality | 2024 |
| Matlock Ecom Ltd | Wholesale & retail | 2020 |
| Matrix Energy Holdings Ltd | Financial services | 2017 |
| Matrix Energy Systems Ltd | Manufacturing | 2009 |
| Matsuko Direct Limited | Wholesale & retail | 2015 |
| MATT7A Limited | Information & communication | 2021 |
| Mattressonline.Co.Uk Ltd | Wholesale & retail | 2004 |
| Maverick Air Conditioning Ltd | Construction | 2026 |