| MCV Solutions Limited | Professional & scientific | 2013 |
| MD Concepts Limited | Information & communication | 2015 |
| MD Estate Group Ltd | Real estate | 2025 |
| MD Global Real Estate Limited | Real estate | 2026 |
| MD Holdings International Limited | Financial services | 2026 |
| MD Property Solutions Global Limited | Health & social care | 2026 |
| MDC Logistics Solutions Limited | Transport & logistics | 2024 |
| Mdev Utilities Ltd | Construction | 2025 |
| MDF Electrical Contractors Ltd | Construction | 2025 |
| MDM Hire Ltd | Administrative & support | 2024 |
| MDM Lifting Solutions Limited | Wholesale & retail | 2023 |
| MDP Audit Solutions Limited | Professional & scientific | 2014 |
| MDS Global Sourcing Limited | Wholesale & retail | 2025 |
| MDS Lettings Ltd | Real estate | 2024 |
| MDS Ortho Ltd | Health & social care | 2016 |
| Mdsolve Ltd | Administrative & support | 2017 |
| MDW Design Services Ltd | Professional & scientific | 2020 |
| ME Financial Services Ltd | Financial services | 2018 |
| Me-Losophy CIC | Health & social care | 2025 |
| Meadow Home Care Services Limited | Health & social care | 2003 |
| Meadows Edge (Hereford) Management Company Limited | Extraterritorial | 2016 |
| Meah Ltd | Hospitality | 2017 |
| Measey Group Ltd | Financial services | 2023 |
| Mebel Limited | Manufacturing | 2025 |
| Mech GEN Power Ltd | Professional & scientific | 2024 |
| Mech-Elec ENG Ltd | Professional & scientific | 2025 |
| Medi Spice Ltd | Hospitality | 2024 |
| Media Matchmaker Limited | Professional & scientific | 2019 |
| Medical Ultrasound & Maternity Services (Mums) Limited | Extraterritorial | 2009 |
| Medical Ultrasound and Midwifery Services (Mums) Limited | Extraterritorial | 2012 |
| Medichem Pharma Services Ltd | Wholesale & retail | 2026 |
| Medicive Ltd | Health & social care | 2018 |
| Medicland Limited | Health & social care | 2025 |
| Medico Audiology Services Ltd | Health & social care | 2015 |
| Medico Electrodes Limited | Manufacturing | 2012 |
| Medicolx Limited | Health & social care | 2023 |
| Medicore Khan Ltd | Health & social care | 2024 |
| Medicstutor Limited | Education | 2025 |
| Medilinx Ltd | Health & social care | 2024 |
| Medimarketing Limited | Information & communication | 2025 |
| Medisafe Dispensing Systems Limited | Information & communication | 2011 |
| Medispire Limited | Professional & scientific | 2017 |
| Mediumship & Magick Ltd | Other services | 2026 |
| Mediumship With LIZ Ltd | Other services | 2023 |
| Medspace Consultancy Ltd | Health & social care | 2025 |
| Medway Galvanising Company Limited | Manufacturing | 1984 |
| Meen Mods Ltd | Wholesale & retail | 2026 |
| Meeso Limited | Health & social care | 2025 |
| Mega Homes Limited | Real estate | 2019 |
| Megacreations Limited | Health & social care | 2014 |
| Mehta Properties Ltd | Real estate | 2016 |
| Mejo Properties Ltd | Real estate | 2017 |
| Mekanova Solutions Ltd | Information & communication | 2026 |
| Mel's Little Luxuries Limited | Manufacturing | 2013 |
| Melbrook Ltd | Professional & scientific | 2024 |
| Melita Property Investment Ltd | Real estate | 2022 |
| Mell Square Limited | Real estate | 2003 |
| Mellifera Homes Ltd | Health & social care | 2023 |
| Melrose Care Group Ltd | Health & social care | 2023 |
| Melynda Jayne at the Prom House Limited | Wholesale & retail | 2024 |
| MEM Saab (Leamington Spa) Limited | Hospitality | 2007 |
| Mem-Saab (Northampton) Limited | Hospitality | 2000 |
| Memsaab Group Limited | Hospitality | 2019 |
| Menclark Community Property Limited | Real estate | 2023 |
| Mend by Mail Ltd | Other services | 2022 |
| Menzies Design and Print Ltd | Manufacturing | 2020 |
| MEP Solutions UK. Ltd | Construction | 2022 |
| Meraki Events Ltd | Hospitality | 2023 |
| Meranti Building Services Ltd | Construction | 2019 |
| Mercanova Trading Limited | Wholesale & retail | 2026 |
| Mercia Hire Solutions Ltd | Construction | 2026 |
| Mercia Industrial Holdings Ltd | Financial services | 2026 |
| Mercia Park Management Company Limited | Real estate | 2020 |
| Mercia Projects Limited | Extraterritorial | 2023 |
| Mercury Building Services (Solihull) Limited | Construction | 2017 |
| Mercy Investments Ltd | Financial services | 2024 |
| Meredith Homes Ltd | Real estate | 2017 |
| Mereside Homes Ltd | Construction | 2023 |
| Merge Design and Homes Ltd | Real estate | 2025 |
| Meri Consultancy Limited | Professional & scientific | 2023 |
| Merk (2016) Limited | Administrative & support | 2023 |
| Merlin Living Limited | Wholesale & retail | 2011 |
| Merlin Technology UK Limited | Wholesale & retail | 2006 |
| Merrion Group Holdings Limited | Financial services | 2020 |
| Merrion Project 1 Limited | Construction | 2021 |
| Merrl Properties Ltd | Real estate | 2024 |
| Mertax Limited | Professional & scientific | 2024 |
| Messiah Boutique Limited | Manufacturing | 2021 |
| Messiah Events Limited | Public administration | 2022 |
| Messiah Lettings Limited | Real estate | 2022 |
| Messiah Recruitment Limited | Administrative & support | 2022 |
| Messiah Sports Limited | Arts & recreation | 2022 |
| Mesterbrook Limited | Real estate | 2001 |
| Metal Components & Fabrication Services Ltd | Manufacturing | 2022 |
| Metal Gutter Company Ltd | Construction | 2026 |
| Metal Packaging International Limited | Wholesale & retail | 2004 |
| Metal Protection Services Limited | | 1986 |
| Metalmould Properties Limited | Real estate | 1991 |
| Method Recruitment Group Ltd | Administrative & support | 2025 |
| METHOD27 Ltd | Wholesale & retail | 2025 |