| MEP Fabrications Ltd | Construction | 2022 |
| MEP Group Holdings Ltd | Financial services | 2025 |
| MEP Projects (UK) Ltd | Construction | 2020 |
| Merchant Services Consulting Limited | Financial services | 2025 |
| Merci Limited | Wholesale & retail | 2010 |
| Mercia Consulting Limited | Education | 2022 |
| Mercia Insurance Brokers Limited | Financial services | 2015 |
| Mercia Murals CIC | Arts & recreation | 2024 |
| Mercia Northstar Group Ltd | Administrative & support | 2026 |
| Merge Creative Ltd | Professional & scientific | 2025 |
| Meridian Flight Systems Ltd | Professional & scientific | 2023 |
| Meridianiq Limited | Information & communication | 2026 |
| Meridienne Exhibitions Limited | Administrative & support | 1997 |
| Meroke LLP | | 2026 |
| Merrynissey Limited | Financial services | 2016 |
| Mertex Distribution Limited | Transport & logistics | 2024 |
| Mertex UK Limited | Other services | 1995 |
| MES Systems Limited | Administrative & support | 2004 |
| Mesa Support Limited | Health & social care | 2016 |
| Metafix Limited | Construction | 2009 |
| Metaversal Limited | Information & communication | 2015 |
| Metcalfe Timber & Builders Merchants Ltd | Manufacturing | 2008 |
| Metropia Partners Limited | Extraterritorial | 2015 |
| Mevia Analytics Ltd | Professional & scientific | 2025 |
| MG Design and Print Limited | Manufacturing | 2019 |
| MG Rivers Limited | Wholesale & retail | 2018 |
| MG1 Solutions Ltd | Other services | 2011 |
| MGC (Midlands) Group Ltd | Transport & logistics | 2023 |
| MGF Associates Ltd | Professional & scientific | 2007 |
| MGR Fluid Engineering Ltd | Professional & scientific | 2024 |
| MGS Design Solutions Ltd | Professional & scientific | 2013 |
| MH London Design Limited | Wholesale & retail | 2016 |
| MHD Logistics Ltd | Transport & logistics | 2021 |
| Miab Limited | Financial services | 2020 |
| Miami Solutions Ltd | Wholesale & retail | 2022 |
| MIB Digital Limited | Information & communication | 2019 |
| Michael Anderson Associates Ltd | Information & communication | 2009 |
| Michael D Mancini Limited | Wholesale & retail | 2025 |
| Micro Technology Solutions Limited | Real estate | 2000 |
| Microscope Optical Services Ltd | Wholesale & retail | 2002 |
| MID Warwickshire Society for Mentally Handicapped Children and Adults | Health & social care | 1990 |
| Midas Gold Shop Limited | Wholesale & retail | 2025 |
| Midcon (UK) Limited | Construction | 2002 |
| Middle Hunscote Farm Equestrian Limited | Other services | 2023 |
| Middleton IMS Limited | Professional & scientific | 2014 |
| Midesh Ltd | Real estate | 2016 |
| Midi Underground Holdings Ltd | Financial services | 2022 |
| Midi Underground Music Ltd | Information & communication | 2022 |
| Midi Underground Records Ltd | Information & communication | 2022 |
| Midi Underground Tech Ltd | Information & communication | 2022 |
| Midland Aesthetic Clinical Services Limited | Health & social care | 2017 |
| Midland Carpets Limited | Construction | 2007 |
| Midland Worktop Fitters Ltd | Construction | 2018 |
| Midlands Automotive Parts Limited | Wholesale & retail | 2024 |
| Midlands Dance Academy Ltd | Arts & recreation | 2024 |
| Midlands Design Flooring Ltd | Construction | 2022 |
| Midlands Plastering and Rendering Services Limited | Construction | 2019 |
| Midlands Stockholding Ltd | Professional & scientific | 2015 |
| Midlands Waste Management Limited | Water & waste | 2019 |
| Midnight Forge Ltd | Information & communication | 2023 |
| Midnightstar Ltd | Professional & scientific | 2012 |
| Mike Barratt Consulting Limited | Professional & scientific | 2009 |
| Mike LEE Management Limited | Professional & scientific | 2020 |
| Mike LEE Publishing Limited | Administrative & support | 2014 |
| Mike Linforth Limited | Information & communication | 2012 |
| Mike Nutting Limited | Professional & scientific | 2012 |
| Mila & J Limited | Hospitality | 2024 |
| Milelux Ltd | Transport & logistics | 2025 |
| Miles of Tiles Imports Limited | Construction | 1999 |
| Milfield Properties Limited | Construction | 2013 |
| Milford & Marah Ltd | Professional & scientific | 2014 |
| Milford Court Residents Association (Leamington Spa) Limited | Real estate | 2014 |
| Milk Bar Studios Limited | Professional & scientific | 2014 |
| Millenium Property Management Ltd | Households | 2020 |
| Millennium Balti Event Ltd | Hospitality | 2024 |
| Mills CNC Automation Limited | Extraterritorial | 2018 |
| Mills CNC Finance Limited | Financial services | 1980 |
| Mills CNC Limited | Manufacturing | 1974 |
| Millside Estates Limited | Real estate | 2022 |
| Millview Group Holdings Limited | Financial services | 2026 |
| Millview Holdings Limited | Financial services | 2026 |
| Millview Prop Limited | Real estate | 2024 |
| Millward Wealth Management Limited | Professional & scientific | 2019 |
| Milverton Hall Management Company Ltd | Households | 2021 |
| Milverton Homes Limited | Construction | 2021 |
| Milverton House Management Company Limited | Households | 1983 |
| Milverton Lodge Management (Leamington) Limited | Households | 2016 |
| MIN EXP Limited | Administrative & support | 2017 |
| MIN Train Limited | Education | 2020 |
| Mind LAB Pro Ltd | Wholesale & retail | 2019 |
| Mindfull Ltd | Wholesale & retail | 2026 |
| Minerva Neurological Consultancy Ltd | Health & social care | 2018 |
| Minibuses 4U Ltd | Transport & logistics | 2013 |
| Ministry of Aesthetics Limited | Health & social care | 2019 |
| Minuet Properties Ltd | Construction | 2024 |
| Miro Media Limited | Information & communication | 2002 |
| Mirthen Ltd | Wholesale & retail | 2024 |
| Mission Brands Consulting UK Ltd | Professional & scientific | 2025 |
| Mister Sandman Limited | Wholesale & retail | 1985 |
| MIU Sheung LEE Limited | Hospitality | 2014 |