| MBN Arts Limited | Education | 2015 |
| Mbongeh Carers Ltd | Health & social care | 2022 |
| Mbor Construction Services Ltd | Construction | 2019 |
| MBS Commercial Property Limited | Real estate | 2004 |
| MBS Fabrications Limited | Construction | 2012 |
| MBS Homes LLP | | 2020 |
| MBS Surveys Ltd | Construction | 2019 |
| MC Digital Media Ltd | Information & communication | 2014 |
| MCA UK Limited | Wholesale & retail | 1993 |
| MCB Mechanical Limited | Professional & scientific | 2024 |
| Mcbain (Southern) Ltd | Construction | 2010 |
| MCC Beauty Limited | Other services | 2026 |
| MCC Food Ltd | Hospitality | 2024 |
| MCC Marine Limited | Administrative & support | 2020 |
| Mccaffrey Property Services Limited | Real estate | 2018 |
| Mccarthy & Stone (Developments) Limited | Construction | 2008 |
| Mccarthy & Stone (Equity Interests) Limited | Real estate | 2005 |
| Mccarthy & Stone (Extra Care Living) Limited | Real estate | 2009 |
| Mccarthy & Stone (Home Equity Interests) Limited | Real estate | 2006 |
| Mccarthy & Stone (Shared Ownership) Limited | Real estate | 2019 |
| Mccarthy & Stone (Total Care Living) Limited | Real estate | 2007 |
| Mccarthy & Stone Investment Properties NO.23 Limited | Real estate | 2008 |
| Mccarthy & Stone Lifestyle Services Limited | Financial services | 2010 |
| Mccarthy & Stone Limited | Professional & scientific | 2008 |
| Mccarthy & Stone Management Services Limited | Real estate | 2010 |
| Mccarthy & Stone Rental Properties Limited | Real estate | 2019 |
| Mccarthy & Stone Rental Properties NO. 2 Limited | Real estate | 2019 |
| Mccarthy & Stone Rental Properties NO. 3 Limited | Real estate | 2019 |
| Mccarthy & Stone Rental Properties NO. 4 Limited | Real estate | 2020 |
| Mccarthy & Stone Resales Limited | Real estate | 2017 |
| Mccarthy & Stone Retirement Lifestyles Limited | Construction | 2008 |
| Mccarthy & Stone Total Care Management Limited | Real estate | 2009 |
| Mccarthy Browne Ltd | Professional & scientific | 2020 |
| Mccarthy&Kim EDU Ltd. | Education | 2022 |
| Mccools Construction Group Limited | Construction | 2022 |
| Mccords Management Services Ltd | Administrative & support | 2021 |
| Mccormick Property Limited | Real estate | 2016 |
| Mccrudden Management Services Limited | Real estate | 2015 |
| Mcculloch Design Services Limited | Professional & scientific | 2016 |
| MCE Developments LLP | | 2024 |
| Mcghee Price-Smith LLP | | 2021 |
| Mcgowan Electrical Services Limited | Construction | 2015 |
| Mchez Limited | Manufacturing | 2019 |
| Mckerl Sales and Management Limited | Wholesale & retail | 2024 |
| Mckinley Investments Limited | Manufacturing | 2016 |
| Mckinley Waterhouse Associates Limited | Administrative & support | 2018 |
| MCL Express Ltd | Transport & logistics | 2022 |
| MCM Mechanical Ltd | Construction | 2019 |
| Mcmurray Consultants Limited | Construction | 2012 |
| MCP (Poole) Limited | Construction | 2009 |
| MCP Acquisitions Limited | Administrative & support | 2018 |
| Mcquoid Carpentry and Construction Ltd | Construction | 2025 |
| Mcquoid Developments Ltd | Construction | 2025 |
| Mcscosh Ltd | Health & social care | 2007 |
| Mcsedg Ltd | Information & communication | 2022 |
| Mcvidmar Ltd | Information & communication | 2016 |
| MD Corporate Relocations Ltd | Hospitality | 2023 |
| MD Johnson Electrical Limited | Construction | 2017 |
| MD Pro Solutions Limited | Manufacturing | 2023 |
| MD Property Services Bournemouth Ltd | Construction | 2025 |
| MD Services Southern Ltd | Other services | 2018 |
| MDH Plumbing & Heating (South Coast) Ltd | Construction | 2012 |
| MDJ Installation Limited | Wholesale & retail | 2019 |
| MDL Property Maintenance Ltd | Construction | 2024 |
| MDM Commercial Holding Ltd | Real estate | 2026 |
| MDR Audit Solutions Ltd | Professional & scientific | 2026 |
| MDT Global Solutions Ltd. | Health & social care | 2013 |
| MDU Electrical & Property Maintenance Ltd | Construction | 2021 |
| ME Taylor Holdings Limited | Administrative & support | 2021 |
| Me.Ha.Gee International Ltd | Wholesale & retail | 2022 |
| Mead Court (Southbourne) Management Limited | Households | 1991 |
| Meadia Ltd | Information & communication | 2008 |
| Meadowsweet Posies Ltd | Wholesale & retail | 2016 |
| Meadwater Management Limited | Real estate | 1975 |
| Mean Consolidation Ltd | Construction | 2025 |
| Measured Technical Solutions Limited | Financial services | 2022 |
| MEB Food Truck Ltd | Manufacturing | 2024 |
| Mebboom Ltd | Information & communication | 2022 |
| MEC Property Investments Ltd | Real estate | 2021 |
| Mechtite Ltd | Construction | 2022 |
| MED Vibes Ltd | Administrative & support | 2022 |
| Medcamps Ltd | Education | 2023 |
| Medi Alarm 247 Limited | Health & social care | 2021 |
| Medi Innovation Ltd | Wholesale & retail | 2003 |
| Mediashockz Ltd | Information & communication | 2003 |
| Medica Writing Ltd | Administrative & support | 2023 |
| Medical Advantage Limited | Education | 2021 |
| Medical Finance Academy Ltd | Wholesale & retail | 2025 |
| Medical Services South Ltd | Health & social care | 2025 |
| Medico-Legal Psychiatry Limited | Health & social care | 2021 |
| Medluxe Energy Ltd | Administrative & support | 2023 |
| Medora Medi Tours Ltd | Administrative & support | 2025 |
| Medsana Ltd | Transport & logistics | 2022 |
| Meducators UK Ltd | Education | 2018 |
| Medway Precast Erection Limited | Wholesale & retail | 1989 |
| Medycle Limited | Professional & scientific | 2019 |
| Meechai Ltd | Hospitality | 2024 |
| Meet George Limited | Information & communication | 2024 |
| Meet Parker Ltd | Information & communication | 2020 |
| Mega Monkey Ltd | Wholesale & retail | 2021 |