| MAP Property Ventures Ltd | Real estate | 2023 |
| MAP the Territory Ltd | Professional & scientific | 2019 |
| Mapa London RIO Limited | Manufacturing | 2017 |
| Maple Estate & Letting Agents Limited | Real estate | 2000 |
| Maple Estate Agents Limited | Real estate | 2000 |
| Maple Infotech Ltd | Information & communication | 2020 |
| Maple Land & Development Limited | Real estate | 2017 |
| Maples Investments Limited | Real estate | 2006 |
| Maplite Enterprises Ltd | Wholesale & retail | 2013 |
| Mapus Holdings Limited | Financial services | 2013 |
| Mapus London Ltd | Real estate | 2014 |
| MAQ Snacks Ltd | Hospitality | 2018 |
| MAR Construct 24/7 Ltd | Construction | 2022 |
| MAR Drylining Solutions Ltd | Construction | 2014 |
| Mara Investments Limited | Financial services | 2021 |
| Mara Shop Limited | Wholesale & retail | 2021 |
| Maranda Court Flat 1 Ltd | Real estate | 2025 |
| Maraschino Professional Limited | Professional & scientific | 2017 |
| Marble & Marble Limited | Construction | 2013 |
| Marble Arch Management Limited | Hospitality | 2007 |
| Marble Arch Real Estate Limited | Real estate | 2017 |
| Marble Archi Ltd | Wholesale & retail | 2025 |
| Marble Oak Limited | Other services | 2013 |
| Marc Oberon Entertainments Limited | Arts & recreation | 2003 |
| Marcamor Consulting Limited | Information & communication | 2025 |
| Marcan Automotive Ltd | Wholesale & retail | 2020 |
| Marcan Ventures Ltd | Real estate | 2019 |
| Marcatus QED (Europe) Limited | Wholesale & retail | 2001 |
| March Lane Properties Limited | Real estate | 2022 |
| Marchbank House (Northwood) Limited | Households | 2006 |
| Marcia LEE Limited | Other services | 2024 |
| Marciero Construction Ltd | Construction | 2025 |
| Marco Aguiar Ltd | Transport & logistics | 2023 |
| Marco Nannini Ltd | Information & communication | 2009 |
| Marcrus Property Ltd | Real estate | 2023 |
| Mardy COW Limited | Information & communication | 2019 |
| Mareev Consulting Ltd | Other services | 2008 |
| Marekmotor Supplies Ltd | Wholesale & retail | 2025 |
| Marfatia Limited | Real estate | 2024 |
| Marfix Solutions Limited | Arts & recreation | 2022 |
| Marga Mania Hair & Beauty Salon Ltd | Other services | 2019 |
| Margil Limited | Households | 1982 |
| Margo Manning Ltd | Education | 2013 |
| Margot Consulting Limited | Professional & scientific | 2024 |
| Maria Books Global Ltd | Information & communication | 2024 |
| Maria Farrar Workshop Limited | Arts & recreation | 2018 |
| Maria Trevers Productions Limited | Information & communication | 2008 |
| Maridi Care Ltd | Health & social care | 2026 |
| Marie Simpson Consulting Limited | Information & communication | 2014 |
| Marie Toulouse Property Partnership Limited | Real estate | 2015 |
| Marigold Assets Ltd | Real estate | 2024 |
| Marigold Montessori Ltd | Education | 2025 |
| Marigold Property Ltd | Real estate | 2024 |
| Marigolds Home Ltd | Real estate | 2024 |
| Marijacare Ltd | Health & social care | 2024 |
| Marina Dealers Ltd | Professional & scientific | 2014 |
| Marina Digital Ltd | Information & communication | 2022 |
| Marina Gold Ltd | Real estate | 2021 |
| Marina Park ST Leonards Freehold Limited | Real estate | 2012 |
| Marina Property Ltd | Wholesale & retail | 2014 |
| Marine Electronics Service (SG) PTE. Ltd | Wholesale & retail | 2023 |
| Marine Mutual Services (W.A.) Ltd | Professional & scientific | 2004 |
| Marinero Exploitation Limited | Transport & logistics | 2012 |
| Mariners Books Ltd | Information & communication | 2020 |
| Mariners Productions Limited | Information & communication | 2018 |
| Marinolla Ltd | Extraterritorial | 2015 |
| Mario & M Limited | Construction | 2023 |
| Mariotrams Limited | Transport & logistics | 2018 |
| Maritime Education & Training Limited | Education | 2002 |
| Maritime Management Limited | Transport & logistics | 2016 |
| Marius Paving Limited | Construction | 2021 |
| Marjo SH Ltd | Hospitality | 2023 |
| Mark Adam Fashions Limited | Real estate | 2002 |
| Mark B Developments Ltd | Real estate | 2021 |
| Mark B Investments Ltd | Real estate | 2020 |
| Mark B Properties Limited | Real estate | 2011 |
| Mark Building Services Limited | Construction | 2012 |
| Mark Davage Property Maintenance Limited | Construction | 1997 |
| Mark Godleman Rigging Services Limited | Construction | 2012 |
| Mark IND Spices Limited | Other services | 2002 |
| Mark James Property Solutions Ltd. | Construction | 2016 |
| Mark Jenner Associates Limited | Professional & scientific | 2004 |
| Mark Lipman Associates Ltd | Professional & scientific | 2015 |
| Mark Reeves Properties Limited | Construction | 2018 |
| Mark Van OSS & Associates Limited | Administrative & support | 2001 |
| Marka Homes Ltd | Real estate | 2022 |
| Markbase Limited | Wholesale & retail | 2005 |
| Market Access Solutions Limited | Professional & scientific | 2014 |
| Market Dash Ltd | Wholesale & retail | 2025 |
| Market Emergence Investments Limited | Real estate | 2024 |
| Market Emergence Ltd | Health & social care | 2019 |
| Market Grove Ltd | Wholesale & retail | 2026 |
| Market Matters Limited | Administrative & support | 2002 |
| Market Mettle Limited | Other services | 2006 |
| Market Place (Nuneaton) Limited | Real estate | 2019 |
| Market Promotions (LDN) Limited | Real estate | 2018 |
| Marketing Projects House Limited | Administrative & support | 1997 |
| Marketmerge Ltd | Wholesale & retail | 2024 |
| Marksity Ltd | Wholesale & retail | 2025 |
| MARK’S1 Construction Ltd | Construction | 2022 |