| Manorsec Ltd | Administrative & support | 2024 |
| Mansiones Management Company Ltd | Households | 2007 |
| Mansiones Management Company NO 2 Limited | Households | 2008 |
| Manta Search Limited | Administrative & support | 2024 |
| Mantra Global Ltd | Real estate | 2019 |
| Mantz DOW Limited | Professional & scientific | 2020 |
| Maple ( 171 ) Limited | Households | 2002 |
| Maple ( 172 ) Limited | Households | 2002 |
| Maple (173) Limited | Households | 2002 |
| Maple (174) Limited | Households | 2002 |
| Maple (177) Limited | Households | 2002 |
| Maple (193) Limited | Households | 2003 |
| Maple (197) Limited | Households | 2003 |
| Maple (198) Limited | Households | 2003 |
| Maple (201) Limited | Households | 2003 |
| Maple (202) Limited | Households | 2003 |
| Maple (207) Limited | Households | 2003 |
| Maple (215) Limited | Households | 2004 |
| Maple (230) Limited | Households | 2004 |
| Maple (268) Limited | Households | 2005 |
| Maple (269) Limited | Households | 2005 |
| Maple Business Services Limited | Professional & scientific | 2008 |
| Maple Consultancy Limited | Agriculture & fishing | 2008 |
| Maple Court (Lincs) Limited | Households | 2004 |
| Mapleton Limited | Administrative & support | 1992 |
| MAR Design Limited | Construction | 2004 |
| Mara Homes (Shrewsbury) Limited | Construction | 2010 |
| Mara Homes Shropshire Limited | Construction | 2010 |
| Marangco Limited | Information & communication | 2021 |
| Maras 46 Limited | Hospitality | 2023 |
| Marbles PR Ltd | Professional & scientific | 2007 |
| Marcela Ltd | Administrative & support | 2025 |
| March One Limited | Wholesale & retail | 2003 |
| Marche Lettings Limited | Hospitality | 2024 |
| Marche Tales Limited | Information & communication | 2016 |
| Marcher Apple Network | Agriculture & fishing | 1999 |
| Marches Academy Trust | Education | 2011 |
| Marches Asset Supportability Ltd | Professional & scientific | 2018 |
| Marches Care Newport Limited | Professional & scientific | 2009 |
| Marches Consultancy Limited | Professional & scientific | 1999 |
| Marches Energy Advice | Information & communication | 1997 |
| Marches Parts Company Ltd | Wholesale & retail | 2025 |
| Mardon Financial Advisers Limited | Financial services | 1987 |
| Mardon House Teignmouth Management Limited | Real estate | 2016 |
| Maresh Holdings Ltd | Real estate | 2024 |
| Marina House Management Company Limited | Households | 2001 |
| Marine Terrace Management Company Limited | Households | 2005 |
| Marisata Limited | Health & social care | 2014 |
| Mark Building Construction Limited | Construction | 2011 |
| Mark Bywater Limited | Construction | 2002 |
| Mark Jones Electrical Services Limited | Construction | 2018 |
| Mark Jones Plastering Ltd | Construction | 2013 |
| Mark Morison Limited | Real estate | 2015 |
| Mark Richards Aviation Consultancy Ltd | Professional & scientific | 2015 |
| Mark Swain Transport Ltd | Extraterritorial | 2011 |
| Mark Thomas Engineering Limited | Construction | 2012 |
| Markite Flat Management Limited | Households | 1998 |
| Marlborough Park (Tamworth) Management Limited | Households | 2008 |
| Marling Car Sales Ltd | Wholesale & retail | 2020 |
| Marlo Enterprises Limited | Wholesale & retail | 2021 |
| Marnco Hotels & Rooms Limited | Real estate | 2009 |
| Marrington Escapes Limited | Real estate | 2009 |
| Marsh Developments (Shropshire) Ltd | Real estate | 2026 |
| Marshalls Heating Company Ltd | Construction | 2020 |
| Marsim SA Ltd | Hospitality | 2018 |
| Marston Electrical Limited | Construction | 2022 |
| Marston Food Marketing Limited | Manufacturing | 1987 |
| Martin and Martin Limited | Wholesale & retail | 2023 |
| Martin Irish Limited | Arts & recreation | 2005 |
| Martin Jones Building and Restoration Limited | Construction | 2009 |
| Martin Reader Ltd | Professional & scientific | 2011 |
| Marting Consulting Limited | Professional & scientific | 2018 |
| Martonia Management Company Limited | Households | 2004 |
| Martyn Williams Plumbing and Heating Limited | Construction | 2010 |
| Mary Frances Gardiner Properties LLP | | 2020 |
| Maryland Court Management Company Limited | Administrative & support | 2008 |
| Marz Ventures Limited | Professional & scientific | 2012 |
| Mason Analytics Limited | Professional & scientific | 2012 |
| Mason Cattle Company Ltd | Extraterritorial | 2024 |
| Masonbees Pollination Limited | Professional & scientific | 2021 |
| Masonic Properties Limited | Hospitality | 2009 |
| Masons Holdings(Shrewsbury) Ltd | Real estate | 2021 |
| Mastek Engineering Ltd | Wholesale & retail | 2018 |
| Masteragency Limited | Arts & recreation | 1998 |
| Masterclad Ltd | Construction | 2015 |
| Mastergrass Ground Maintenance Limited | Administrative & support | 2021 |
| Masterplank Limited | Manufacturing | 2021 |
| Matchnx Limited | Information & communication | 2026 |
| Matedcare Ltd | Health & social care | 2018 |
| Matematika Limited | Wholesale & retail | 2024 |
| Material Clothing Ltd | Wholesale & retail | 2022 |
| Mateus Machado Ltd | Professional & scientific | 2024 |
| Matola Limited | Manufacturing | 2023 |
| Matrix Capital Limited | Financial services | 2004 |
| Matrix IDC Limited | Construction | 2001 |
| Matrix Joinery Limited | Construction | 2020 |
| Matrix Occupational H&S Ltd | Health & social care | 2014 |
| Mattel Trustees Ltd | Real estate | 2017 |
| Matthew Cooper Writing Limited | Arts & recreation | 2018 |
| Matthews & Peart Holdings Limited | Financial services | 2026 |