| Marbo Capital Limited | Professional & scientific | 2003 |
| Marc Coleman Electrical Services Limited | Construction | 2014 |
| Marc Webb Building Ltd | Construction | 2018 |
| Marc Webb Homes Ltd | Construction | 2025 |
| Marcellus Capital Ltd | Professional & scientific | 2015 |
| Marcelo Prebianchi Limited | Health & social care | 2019 |
| March Heritage Homes Limited | Construction | 2017 |
| March Limited | Wholesale & retail | 2000 |
| March Retailing Ltd | Wholesale & retail | 2014 |
| Marchant Best Properties Limited | Real estate | 2025 |
| Marchbank Ltd | Construction | 2018 |
| Marchington House Limited | Real estate | 2007 |
| Marchini Curran Associates Limited | Professional & scientific | 2001 |
| Marchini Curran Engineering Limited | Professional & scientific | 2015 |
| Marchini Curran Holdings Limited | Professional & scientific | 2015 |
| Marchini Curran Interiors Ltd | Professional & scientific | 2016 |
| Marchini Curran Planning Ltd | Professional & scientific | 2016 |
| Marciana Homes Ltd | Real estate | 2024 |
| Marcin Motor Engineers Ltd | Wholesale & retail | 2025 |
| Marcin Stachurski Dressage Limited | Education | 2018 |
| Marck Limited | Education | 2017 |
| Marco Construct Ltd | Construction | 2023 |
| Marco Polo Market Ltd | Wholesale & retail | 2024 |
| Marcus Ecomm Ltd | Wholesale & retail | 2026 |
| Marcus Garvey Action Group Ltd | Health & social care | 2022 |
| Marcus Garvey Community CIC | Real estate | 2025 |
| Marcuscooks Ltd | Hospitality | 2023 |
| Marc’S Plumbing & Heating Ltd | Construction | 2026 |
| Mardan Traders Ltd | Wholesale & retail | 2024 |
| Mardel Commercial Interiors Limited | Wholesale & retail | 2023 |
| Mardy BUM Brew Co Ltd | Manufacturing | 2021 |
| Mare (Nottingham) Ltd | Hospitality | 2012 |
| Marel Studios Ltd. | Wholesale & retail | 2021 |
| Marestransport Ltd | Wholesale & retail | 2024 |
| Marfo Consultancy Limited | Administrative & support | 2025 |
| Marfor Properties Limited | Real estate | 2018 |
| Margalla Services Limited | Health & social care | 2013 |
| Margaret Cleaning/Nice and Fresh Ltd | Administrative & support | 2023 |
| Margatsni Limited | Wholesale & retail | 2020 |
| Marginfold Press Ltd | Information & communication | 2025 |
| Margo and Plum Emporia Limited | Wholesale & retail | 2019 |
| Margo and Plum Ltd | Wholesale & retail | 2017 |
| Margo and Plum Priority Logistics Ltd | Transport & logistics | 2022 |
| Margy Avenue Ltd | Arts & recreation | 2024 |
| Mari Properties Ltd | Real estate | 2023 |
| Maria Decor Limited | Administrative & support | 2026 |
| Maria LA Gorda Ltd | Professional & scientific | 2022 |
| Maria Moore Limited | Financial services | 2008 |
| Maria Muganhiri Limited | Health & social care | 2015 |
| Maria Papadopoulou Ltd | Health & social care | 2019 |
| Maria Samara Limited | Health & social care | 2024 |
| Maria Semak Consulting Limited | Professional & scientific | 2013 |
| Maria's Ices Limited | Hospitality | 2014 |
| Marian Case Ltd | Real estate | 2022 |
| Mariana Caterers Limited | Hospitality | 2011 |
| Marianne Florist Ltd | Wholesale & retail | 2024 |
| Maribet Consult Ltd | Information & communication | 2025 |
| Marie Annette Smith Ltd | Professional & scientific | 2025 |
| Marie Hall Hairdressing Ltd | Other services | 2002 |
| Marimar Ltd | Administrative & support | 2012 |
| Marina Balazs Limited | Health & social care | 2018 |
| Marina Park Residents Association Limited | Households | 1990 |
| Marindu Ltd | Wholesale & retail | 2026 |
| Marine Audio Services Limited | Information & communication | 2025 |
| Marine Insulations Ltd | Manufacturing | 2021 |
| Mario Plumbing & Electrical Ltd | Construction | 2024 |
| Mario's Keyworth Ltd | Hospitality | 2026 |
| Mario's Pizza Beeston Limited | Hospitality | 2019 |
| Marion Solutions Ltd | Professional & scientific | 2017 |
| Marios Pizza and Kebab Ltd | Hospitality | 2022 |
| Marios Properties Limited | Real estate | 2002 |
| Marios Takeaway (Keyworth) Limited | Hospitality | 2016 |
| Marisol Healthcare Ltd | Health & social care | 2021 |
| Marius Consulting Ltd | Professional & scientific | 2012 |
| Marius Transport Express Limited | Transport & logistics | 2025 |
| Mariusz Nowicki Ltd | Transport & logistics | 2023 |
| Mark a Savory Ltd | Professional & scientific | 2024 |
| Mark a Stevens Limited | Wholesale & retail | 2006 |
| Mark Addy Productions Ltd | Arts & recreation | 2009 |
| Mark Berresford Rare Records Limited | Wholesale & retail | 2011 |
| Mark Bushnell Limited | Information & communication | 2008 |
| Mark C Taylor Limited | Professional & scientific | 2019 |
| Mark Campbell & Company Ltd | Real estate | 2023 |
| Mark Carroll Ltd | Education | 2015 |
| Mark Consultancy Group Limited | Other services | 2026 |
| Mark Cope Building Limited | Construction | 2017 |
| Mark Dimond Transport Planning Ltd | Professional & scientific | 2026 |
| Mark Douglas Industrial Supplies Limited | Wholesale & retail | 1976 |
| Mark Eddowes Flooring Limited | Construction | 2015 |
| Mark Evans Jewellery Limited | Manufacturing | 2013 |
| Mark Fedulow Training and Learning Consultant Services Limited | Education | 2019 |
| Mark Goodwill-Hodgson Limited | Professional & scientific | 2012 |
| Mark Hastings Properties Ltd | Financial services | 2024 |
| Mark Industries Ltd | Manufacturing | 2019 |
| Mark J Flowers Orthopaedics Ltd | Health & social care | 2013 |
| Mark Maddock Custom Installation Ltd | Professional & scientific | 2007 |
| Mark One Cars Limited | Wholesale & retail | 2020 |
| Mark One Denticare Ltd | Wholesale & retail | 2024 |
| Mark One Services Limited | Construction | 2003 |
| Mark Porter Ltd | Construction | 2018 |