| Marcus Bennett Engineering Ltd | Wholesale & retail | 2020 |
| Mardans Property Ltd | Construction | 2025 |
| Mariota Limited | Real estate | 2023 |
| Mariota Property Limited | Real estate | 2023 |
| Mark Henley Associates Limited | Health & social care | 2015 |
| Market Garden (Glos) Limited | Wholesale & retail | 2015 |
| Market PLACE#1 Ltd | Real estate | 2025 |
| Marketegy Ltd | Professional & scientific | 2020 |
| Marlinspike Hall Limited | Administrative & support | 2020 |
| Marlow Dermatology Ltd | Health & social care | 2021 |
| Marlow Holdings Limited | Extraterritorial | 2017 |
| Marnia Properties Ltd | Real estate | 2018 |
| Marsco Holiday Apartments Limited | Hospitality | 2024 |
| Marsik Ltd | Manufacturing | 2025 |
| Martin Evans Maxillofacial Limited | Health & social care | 2015 |
| Martin's Plumbing and Heating Solutions Ltd | Construction | 2020 |
| Maskroot Ltd | Wholesale & retail | 2018 |
| Masons Window Cleaning Ltd | Administrative & support | 2024 |
| MAT Property Ltd | Administrative & support | 2013 |
| Match Fostercare Limited | Health & social care | 2010 |
| Match-Fit Consultancy Limited | Professional & scientific | 2001 |
| Mate Services Ltd | Transport & logistics | 2026 |
| Matrix Aggregates Developments Limited | Administrative & support | 2018 |
| Matrix Aggregates Limited | Administrative & support | 2005 |
| Matthew O'Neill Limited | Health & social care | 2013 |
| Maximous Electrical Services Ltd | Construction | 2023 |
| Maximum Multidrop Ltd | Transport & logistics | 2017 |
| Mayfield Forestry Ltd | Agriculture & fishing | 2022 |
| Mayhouse Court Development Management Limited | Households | 2001 |
| Maylite Limited | Real estate | 1972 |
| Mayunmite Ltd | Wholesale & retail | 2018 |
| MB Insolvency Limited | Financial services | 2015 |
| MBG Pets Limited | Professional & scientific | 2022 |
| MBG VET Holdings Limited | Financial services | 2022 |
| MBJ Holdings Limited | Real estate | 2021 |
| MCD Heating Limited | Other services | 2009 |
| MCD Projects Limited | Real estate | 2015 |
| MCD Regeneration Consulting Limited | Other services | 2020 |
| MCD Regeneration Limited | Real estate | 2015 |
| Mcmillan and Dunbar Property Ltd | Real estate | 2018 |
| MCN Business Services Ltd | Professional & scientific | 2017 |
| Mcplantgb Ltd | Administrative & support | 2022 |
| MDB Promotions Ltd | Administrative & support | 2023 |
| MDM Holdings (Midlands) Ltd | Financial services | 2022 |
| MDM Plant Hire Limited | Administrative & support | 2011 |
| Meadow Mill Bakery Limited | Manufacturing | 2007 |
| MEC Cleaning Ltd | Administrative & support | 2005 |
| Medical & Legal Investments Ltd | Administrative & support | 2013 |
| Medical Kidney Services Ltd | Health & social care | 2021 |
| Medstars Limited | Professional & scientific | 2014 |
| Melonbox Ltd | Professional & scientific | 2025 |
| Mendiveg Ltd | Hospitality | 2012 |
| Menilopalcloud Ltd | Transport & logistics | 2019 |
| Mentally Unstoppable Limited | Health & social care | 2025 |
| Menti Solutions Ltd | Administrative & support | 2026 |
| Menzies Distribution Logistics Limited | Transport & logistics | 1974 |
| Menzies Distribution Services Limited | Financial services | 1986 |
| Menzies Distribution Solutions Group Limited | Financial services | 2024 |
| Menzies Distribution Solutions Limited | Transport & logistics | 1999 |
| Mercian Property Company Limited | Construction | 2017 |
| Mercurial Holdings Ltd | Agriculture & fishing | 2021 |
| Mercury CS LLP | | 2016 |
| Mercury CSC Limited | Administrative & support | 2016 |
| Mere Green Residents Ltd | Households | 2023 |
| Merit Badge Holdings Ltd | Financial services | 2022 |
| Merlin Barber Shops Ltd | Other services | 2018 |
| Merrington Project Services Limited | Professional & scientific | 2007 |
| Merryvalls Limited | Agriculture & fishing | 2013 |
| Mervolyte Ltd | Manufacturing | 2023 |
| Mesh (Droitwich 24) Limited | Administrative & support | 2024 |
| Meta IQ Limited | Professional & scientific | 2025 |
| Metaphoric Projects Limited | Administrative & support | 2021 |
| Metta Properties Ltd | Real estate | 2014 |
| MF Connor Ltd | Transport & logistics | 2021 |
| MFC Studios Ltd | Arts & recreation | 2025 |
| MFL Equipment Ltd | Manufacturing | 2023 |
| Mfsf Limited | Administrative & support | 2001 |
| MG Trading UK Ltd | Wholesale & retail | 2009 |
| MGL Design Associates Ltd | Professional & scientific | 2016 |
| MGM Global Limited | Real estate | 2020 |
| Micaly Ltd | Information & communication | 2019 |
| Michael Anthony Revell Ltd | Extraterritorial | 2025 |
| MID Construction Group Limited | Construction | 2015 |
| MID Counties Liming & Soil Analysis Limited | Agriculture & fishing | 2024 |
| MID Metering Limited | Administrative & support | 2015 |
| Middleton Manor East Management Co Ltd | Households | 2022 |
| Midland (TW MPF PSM) Group Ltd | Professional & scientific | 2021 |
| Midland Accountancy Services Limited | Professional & scientific | 1995 |
| Midland Classic Restorations Limited | Manufacturing | 2009 |
| Midland Erection Limited | Construction | 1942 |
| Midland Erection Roofing and Cladding Limited | Construction | 2012 |
| Midland Hvac Holdings Limited | Administrative & support | 2020 |
| Midland Hvac Limited | Administrative & support | 2019 |
| Midland Soccer Coaching Limited | Arts & recreation | 2008 |
| Midland Tile Contractors Limited | Construction | 2018 |
| Midlands Allergy Service Ltd | Health & social care | 2023 |
| Midlands Oncology Ltd | Health & social care | 2019 |
| Midlands Oncology Property Limited | Real estate | 2023 |
| Midlands School of Coffee Limited | Manufacturing | 2023 |
| Midlands Wing Chun Kuen Ltd | Arts & recreation | 2010 |