| Maraiwe Limited | Health & social care | 2014 |
| Maran Industries Ltd | Real estate | 2019 |
| Maranatha 1 Limited | Administrative & support | 2014 |
| Maranatha Estates Ltd | Real estate | 2024 |
| Maranatha Foundation | Extraterritorial | 2008 |
| Maranatha Installation Services Limited | Administrative & support | 2007 |
| Maranatha Limited | Information & communication | 2005 |
| Maranatha Ministries | Extraterritorial | 2008 |
| Maranatha Youth Club | Extraterritorial | 2008 |
| Marand Motors Limited | Other services | 1980 |
| Maranello Concessionaires Limited | Wholesale & retail | 1960 |
| Maranello Holdings Limited | Professional & scientific | 1986 |
| Maranello Sales Limited | Wholesale & retail | 1979 |
| Marans Management Company Limited | Households | 2009 |
| Marasiyah Ltd | Manufacturing | 2025 |
| Marathon Clothing UK Limited | Manufacturing | 2020 |
| Maravi Ltd | Administrative & support | 2016 |
| Marazan Limited | Information & communication | 2010 |
| Marbeth Interiors Ltd | Professional & scientific | 2021 |
| Marbeth Properties Ltd | Real estate | 2023 |
| Marbil Distribution Ltd | Wholesale & retail | 2026 |
| Marble Arch Properties Ltd | Real estate | 2024 |
| Marble Arms Ltd | Wholesale & retail | 2019 |
| Marble Building Products (Yorkshire) Limited | Wholesale & retail | 2011 |
| Marble Homes (Leicester) Limited | Real estate | 2007 |
| Marbrooke Electrical Services Ltd | Construction | 2024 |
| Marc Morhange Psychiatry Ltd | Health & social care | 2023 |
| March (Holdings) Limited | Professional & scientific | 2011 |
| March Assets Limited | Financial services | 2022 |
| March Brothers Holdings Limited | Financial services | 2021 |
| Marcin Kisiel Ltd | Transport & logistics | 2016 |
| Marcin Kurowicki Ltd | Transport & logistics | 2013 |
| Marcin Mazur Ltd | Transport & logistics | 2015 |
| Marcinex Ltd | Transport & logistics | 2018 |
| Marco 165 Limited | Financial services | 2012 |
| Marcom Media Services International Ltd | Information & communication | 2024 |
| Marconesc Trans Ltd | Administrative & support | 2018 |
| Marconesc Transport Ltd | Transport & logistics | 2025 |
| Marcopss Ltd | Transport & logistics | 2026 |
| Marcus Bates Limited | Real estate | 2003 |
| Marcus Collie Bloodstock Ltd | Arts & recreation | 2020 |
| Marcus DE Ltd | Manufacturing | 2012 |
| Marek Gumkowski Ltd | Transport & logistics | 2022 |
| Marek Konik Ltd | Transport & logistics | 2016 |
| Marek Usidus Ltd | Transport & logistics | 2025 |
| Marfa Investments Ltd | Real estate | 2021 |
| Marfel Ltd | Information & communication | 2026 |
| Margi Willis Estates Limited | Real estate | 2012 |
| Margin Logic Ltd | Extraterritorial | 2026 |
| Margos Spar Limited | Wholesale & retail | 2012 |
| Marh Trading Limited | Wholesale & retail | 2023 |
| Marhaba Collection Limited | Wholesale & retail | 2023 |
| Marhia Limited | Real estate | 2017 |
| Maria Caldas Consulting Ltd | Administrative & support | 2026 |
| Maria Investments Limited | Extraterritorial | 2022 |
| Maria T Beauty Ltd | Other services | 2023 |
| Maria Watts Ltd | Other services | 2025 |
| Maria's Cleaning Company Ltd | Administrative & support | 2020 |
| Mariana WM Limited | Water & waste | 2016 |
| Maridaki Properties Ltd | Real estate | 2019 |
| Marigold Consulting Ltd | Administrative & support | 2019 |
| Marigold Haven Ltd | Health & social care | 2025 |
| Marigold Maison Limited | Manufacturing | 2020 |
| Marija Tenyte Limited | Other services | 2017 |
| Marimex Insulation and International Trading Ltd | Manufacturing | 2021 |
| Marimina Medical Group Ltd | Health & social care | 2025 |
| Marina Haulage Ltd | Transport & logistics | 2020 |
| Marination Station Ltd | Manufacturing | 2025 |
| Marine Fish Bar Limited | Hospitality | 2018 |
| Marine Fish Bar UK Limited | Hospitality | 2020 |
| MARIO201817 Limited | Transport & logistics | 2023 |
| Marionikolas Ltd | Transport & logistics | 2020 |
| Marios Hospitality Ltd | Wholesale & retail | 2021 |
| Marios Pizza UK Ltd | Hospitality | 2016 |
| Marisco Trading Ltd | Manufacturing | 2022 |
| Marism Architectural Design Services Ltd | Professional & scientific | 2020 |
| Mark Antony Waters Limited | Manufacturing | 2015 |
| Mark Autos Ltd | Wholesale & retail | 2024 |
| Mark Backus Photography Limited | Professional & scientific | 2002 |
| Mark Bailey Joinery Limited | Construction | 2016 |
| Mark Baines Catering Services Ltd | Hospitality | 2013 |
| Mark Charles Storage Ltd | Real estate | 2020 |
| Mark Cross Installations Limited | Construction | 2017 |
| Mark Eynon Photography Limited | Professional & scientific | 2002 |
| Mark Ferguson (Property Services) Limited | Households | 2026 |
| Mark Fiske Design Solutions Ltd | Construction | 2022 |
| Mark G Stevens Ltd | Professional & scientific | 2020 |
| Mark Geeson Physiotherapy Services Limited | Health & social care | 2002 |
| Mark H Mills Transport Limited | Transport & logistics | 2014 |
| Mark Installation Services Limited | Construction | 2007 |
| Mark J Rees LLP | | 2011 |
| Mark Laywood Associates Limited | Professional & scientific | 2024 |
| Mark Leeson Hairdressing Limited | Other services | 2005 |
| Mark Mansfield (MM) Carpentry Ltd | Construction | 2022 |
| Mark Mckeon Limited | Other services | 2003 |
| Mark R Harrison Limited | Professional & scientific | 2011 |
| Mark Selby Snooker Limited | Arts & recreation | 2007 |
| Mark Sharman Limited | Manufacturing | 2014 |
| Mark Skinner Design Ltd | Administrative & support | 2010 |
| Mark Tuckley Builder Landscaper Limited | Construction | 2017 |