| Mccann Property Development Ltd | Construction | 2023 |
| Mccoy Clothings UK Limited | Other services | 2021 |
| MCD Services Ltd | Construction | 2025 |
| Mcdaid Deck Systems Ltd | Construction | 2022 |
| Mcdaid Screeding Services Limited | Construction | 2001 |
| Mcfarland Homes Limited | Construction | 2007 |
| Mcfarlane-Griffith Ltd | Wholesale & retail | 2019 |
| Mcgeorge Physiotherapy Limited | Health & social care | 2025 |
| Mcgill Solutions Limited | Professional & scientific | 2021 |
| Mcgreevy Automation Limited | Manufacturing | 2024 |
| Mcguinness Brothers Construction Ltd | Construction | 2022 |
| Mcguinness Brothers Group Ltd | Financial services | 2024 |
| Mclain Estate Agents Ltd | Real estate | 2024 |
| Mclaudius Services Ltd | Health & social care | 2021 |
| MCM Wines Ltd | Wholesale & retail | 2019 |
| Mcmoodies Ltd | Real estate | 2021 |
| Mcmorrow Ltd | Construction | 2013 |
| Mcneal Jones Group Ltd | Health & social care | 2016 |
| Mcneal Jones Limited | Wholesale & retail | 2022 |
| MCO Logistics Ltd | Transport & logistics | 2024 |
| MCO London Ltd | Construction | 2024 |
| MCS Logistics (Peterborough) Ltd | Administrative & support | 2018 |
| MCS MK Ltd | Wholesale & retail | 2016 |
| Mcsmart Ltd | Real estate | 2023 |
| Mctg Global Ltd | Real estate | 2023 |
| MD America Brand Limited | Extraterritorial | 2014 |
| MD Cleaner Ltd | Administrative & support | 2020 |
| MD Europe Brand Limited | Extraterritorial | 2013 |
| MD Rostas Construction Ltd | Construction | 2025 |
| MD Social Education Limited | Professional & scientific | 2025 |
| MD Solutions Ltd | Other services | 2024 |
| MD Tyres Limited | Wholesale & retail | 2023 |
| Md&S Construction Ltd | Construction | 2019 |
| Md'Luxe Beauty and Aesthetics Ltd | Other services | 2024 |
| MDA Cars Ltd | Wholesale & retail | 2025 |
| MDC Surveying Services Ltd | Professional & scientific | 2020 |
| Mdht Services Ltd | Health & social care | 2023 |
| Mdhuggs Ltd | Professional & scientific | 2014 |
| MDM & Sons Holdings Ltd | Real estate | 2026 |
| MDM Autos & Machinery Limited | Wholesale & retail | 2024 |
| MDM Grab Hire Ltd | Transport & logistics | 2020 |
| Mdmd Construction Ltd | Construction | 2021 |
| MDS Gardening Limited | Administrative & support | 2021 |
| MDS Parts Ltd | Wholesale & retail | 2023 |
| MDS Plant Ltd | Construction | 2020 |
| MDS Sofia Ltd | Transport & logistics | 2026 |
| MDS UK Group Ltd | Financial services | 2020 |
| MDV Agency Ltd | Administrative & support | 2016 |
| Mdzr Limited | Wholesale & retail | 2025 |
| ME Electricals Limited | Construction | 2024 |
| ME Supplies Limited | Other services | 2023 |
| ME. DE. AR. Ltd | Professional & scientific | 2014 |
| Me.Let Homes Ltd | Real estate | 2025 |
| Meadow Products Limited | Administrative & support | 2025 |
| Meadowside (Bishopstone) Management Company Limited | Households | 2019 |
| Meadplan Limited | Administrative & support | 1999 |
| Meads Properties Ltd | Real estate | 2022 |
| Meah Luton Ltd | Hospitality | 2016 |
| Meah's Flavours of India Limited | Wholesale & retail | 1998 |
| Meccraft Limited | Wholesale & retail | 2025 |
| Mechanic FIX Expert Ltd | Wholesale & retail | 2025 |
| Mechanotek Limited | Information & communication | 2026 |
| MECHAPRO2 Ltd | Wholesale & retail | 2024 |
| Medcoach Ltd | Education | 2020 |
| Medi Kitchen Express Ltd | Hospitality | 2024 |
| Medi Kitchen Restaurant Ltd | Hospitality | 2025 |
| Medi Quality Meat Ltd | Wholesale & retail | 2026 |
| Media Pulse UK Ltd | Professional & scientific | 2026 |
| Media Vault Ltd | Information & communication | 2014 |
| Mediainteractive Consulting Limited | Information & communication | 2000 |
| Mediauk Limited | Wholesale & retail | 2025 |
| Medical Business Management Ltd | Administrative & support | 2018 |
| Medical Claims Limited | Other services | 2018 |
| Medical Means Limited | Professional & scientific | 2015 |
| Medical Pharma Supplies Ltd | Wholesale & retail | 2025 |
| Medicare & Mobility Solutions Limited | Health & social care | 2017 |
| Medicare Locums (UK) Ltd | Health & social care | 2010 |
| Medicines R US Limited | Wholesale & retail | 2010 |
| Medicliniq Ltd | Health & social care | 2016 |
| Medina Halal Meat Centre Ltd | Wholesale & retail | 2015 |
| Mediterranean Estates Ltd | Real estate | 2010 |
| Medixa Cleaning Services Ltd | Administrative & support | 2025 |
| Medson Healthcare Ltd | Health & social care | 2020 |
| MEE Sushi Property Ltd | Real estate | 2025 |
| Meed Holdings Ltd | Financial services | 2022 |
| Meedou Chen Ltd | Hospitality | 2024 |
| Meers Paint and Decoration Ltd | Administrative & support | 2023 |
| Meet EAT Drink and Dream Limited | Hospitality | 2016 |
| Meezan Al-Way Limited | Hospitality | 2013 |
| Mefi Ltd | Construction | 2011 |
| Mefts Ltd | Wholesale & retail | 2024 |
| MEG Trading 3 Limited | Real estate | 2011 |
| Mega Cleaning Ltd | Administrative & support | 2018 |
| Mega Engineering Ltd | Construction | 2025 |
| Mega Feast Ltd | Hospitality | 2026 |
| Mega Food Suppliers Ltd | Hospitality | 2022 |
| Mega Groundworks Ltd | Construction | 2025 |
| Mega Mobile Repair Ltd | Wholesale & retail | 2025 |
| Mega Tech Works Limited | Transport & logistics | 2015 |
| Megachain Ltd | Professional & scientific | 2024 |