| Manx Pharma Ltd | Manufacturing | 1996 |
| Manx Properties Limited | Real estate | 2007 |
| Maple (209) Limited | Households | 2003 |
| Marcela Aguirre Ltd | Health & social care | 2021 |
| Marcus Willis Ltd | Arts & recreation | 2022 |
| Margaret Court Limited | Health & social care | 2009 |
| Margaret Hall Limited | Manufacturing | 2002 |
| Margetts Warwick Limited | Real estate | 2014 |
| Maria Nila UK Limited | Wholesale & retail | 2020 |
| Maricott Court Management Company Limited | Households | 2018 |
| Mark Holton Consulting Limited | Administrative & support | 2005 |
| Mark LEE & Co Consulting Ltd | Professional & scientific | 2021 |
| Mark Ryder Consulting Ltd | Professional & scientific | 2025 |
| Market Visibility Limited | Financial services | 2012 |
| Marketer Technologies Limited | Administrative & support | 2015 |
| Marklin Developments Ltd | Construction | 2013 |
| Marknad Ltd | Administrative & support | 2017 |
| Marlborough Court (Eastbourne) Limited | Households | 2000 |
| Marleymanor Limited | Administrative & support | 1991 |
| Marque Models Limited | Manufacturing | 1975 |
| Marron Digital Ltd | Information & communication | 2025 |
| Marrs Invest Limited | Real estate | 2021 |
| Marshall Developments (Warwick) Limited | Construction | 2005 |
| Marshall Music UK Ltd | Administrative & support | 2019 |
| Marson Designs Ltd | Professional & scientific | 2013 |
| Martin Hooke Roofing Contractors Limited | Construction | 2009 |
| Martin Tolliday Limited | Professional & scientific | 2026 |
| Martrade Logistics UK Holding Limited | Administrative & support | 1999 |
| Martrade Shipping Services UK Limited | Transport & logistics | 1999 |
| Marvel Machine Tool Services Ltd | Manufacturing | 2024 |
| Mary Brown's UK Holdings Ltd. | Hospitality | 2023 |
| Masala Knights Ltd | Hospitality | 2018 |
| Mason Foods Limited | Hospitality | 2023 |
| Masonite Beams Ltd | Construction | 2024 |
| Massive Engineering Ltd. | Professional & scientific | 2017 |
| Maths Flow Ltd | Information & communication | 2025 |
| Mathsframe Ltd | Information & communication | 2009 |
| Matmastr Limited | Information & communication | 2025 |
| Matt Adam Enterprises Ltd | Professional & scientific | 2024 |
| Matt Brook Architects Limited | Professional & scientific | 2021 |
| Matt Mcintyre Glass & Glazing Ltd. | Construction | 2017 |
| Matt Simpson Home Improvements Limited | Construction | 2023 |
| Matt Taylor Consultancy Ltd | Professional & scientific | 2019 |
| Matthew James Estates Ltd | Real estate | 2020 |
| Mavenoid Ltd | Administrative & support | 2020 |
| Maxiglaze Ltd | Construction | 2021 |
| Maygate Developments Limited | Real estate | 1983 |
| Maystone Nash Limited | Professional & scientific | 2022 |
| MB Facades Ltd | Construction | 2020 |
| MC Global Solutions Ltd | Information & communication | 2009 |
| MCA Banbury Ltd | Professional & scientific | 1998 |
| MCA Business Holdings Ltd | Financial services | 2015 |
| MCA Business Ltd | Professional & scientific | 2007 |
| MCA Business Services Ltd | Professional & scientific | 2007 |
| MCA Cirencester Ltd | Extraterritorial | 2006 |
| MCA Leamington Ltd | Extraterritorial | 2013 |
| Mcbx Limited | Professional & scientific | 2025 |
| Mccarthy Property Ltd | Construction | 2020 |
| Mccutchion Davis Properties Limited | Real estate | 2017 |
| Mcdaide & Sons Estates Ltd | Real estate | 2024 |
| Mcinta Limited | Wholesale & retail | 2025 |
| Mclwebco. Limited | Information & communication | 2000 |
| MCP Consulting Group Holdings Limited | Financial services | 2023 |
| MCP Technical Training Limited | Administrative & support | 2020 |
| MCS Build Limited | Construction | 2003 |
| MCS Fast Track Limited | Construction | 2005 |
| MCS Group Holdings (Warwick) Limited | Financial services | 2025 |
| MCS Group Holdings Limited | Construction | 2019 |
| MCS Group Limited | Construction | 2004 |
| MCS Special Projects Limited | Construction | 2004 |
| MD & SD Developments Ltd | Construction | 2026 |
| MD Medical Solutions Ltd | Wholesale & retail | 2023 |
| MDC Properties (Southam) Ltd | Real estate | 2019 |
| MDG Architects Ltd | Professional & scientific | 2018 |
| MDG Group Ltd | Financial services | 2016 |
| MDS Warwick Limited | Hospitality | 2017 |
| Mdsoil Limited | Financial services | 2025 |
| MDV Aquilus Ltd | Manufacturing | 2026 |
| ME V ME Limited | Wholesale & retail | 2015 |
| Meadow Castings Ltd. | Manufacturing | 2019 |
| Mean Genie Ltd | Information & communication | 2011 |
| Mechanismo Limited | Information & communication | 2017 |
| Mediaplanet Limited | Professional & scientific | 2004 |
| Medicus Resourcing Limited | Administrative & support | 2010 |
| Medileap Limited | Health & social care | 2022 |
| Mediprojex Limited | Professional & scientific | 2011 |
| Medisupply Ltd | Wholesale & retail | 2023 |
| Medtech Consultants Limited | Real estate | 2009 |
| Medway Navigation and Surveying Ltd | Professional & scientific | 2015 |
| Megaflo Limited | Extraterritorial | 1965 |
| Megafy Holding Limited | Financial services | 2022 |
| Melstan Finance Ltd | Financial services | 2025 |
| Melton Court Limited | Households | 1996 |
| Memorable Moments Photography Ltd | Professional & scientific | 2025 |
| Mensis Legal Services Limited | Professional & scientific | 2020 |
| Mercado Medic UK Limited | Manufacturing | 2007 |
| Mercado UK Limited | Real estate | 2008 |
| Mercia Metals Limited | Water & waste | 1996 |
| Mercury FM Limited | Professional & scientific | 2009 |
| Mercury Infrastructure Services Limited | Administrative & support | 2009 |