| Merah Ventures Ltd | Real estate | 2023 |
| Meraki Plus Ltd | Professional & scientific | 2024 |
| Meraki Property Holdings Ltd | Real estate | 2023 |
| Meraki Recruitment & Consultancy Ltd | Administrative & support | 2024 |
| Meramill Limited | Households | 1989 |
| Meran Homes Limited | Real estate | 2021 |
| Mercantile House Ltd | Construction | 2019 |
| Mercer Sourcing Ltd | Wholesale & retail | 2024 |
| Merchant's Transaction Finance Ltd | Financial services | 2011 |
| Merchants Court (Newbury) Management Company Limited | Real estate | 2015 |
| Merchants House Management Company Limited | Households | 1996 |
| Mercian Logistics Limited | Transport & logistics | 2000 |
| Mercier Apartments (Putney) Management Company Limited | Households | 2005 |
| Mercsol Ltd | Administrative & support | 2020 |
| Mercury Multimedia Ltd | Professional & scientific | 1999 |
| Mercury&Co Trading Ltd | Wholesale & retail | 2025 |
| Mercy & Grace Healthcare Limited | Health & social care | 2023 |
| Mercy Global Ltd | Wholesale & retail | 2024 |
| Mercy's Integrated Care Limited | Health & social care | 2015 |
| Mere END Management Company Limited | Households | 2002 |
| Mere Igho Ltd | Wholesale & retail | 2020 |
| Mere Park (Winsford) Management Company Limited | Households | 2005 |
| Mereside Management Company Limited | Households | 2003 |
| Meressa Property Group Ltd | Real estate | 2021 |
| Meresworth Property Holdings Ltd | Households | 2026 |
| Merewood Gardens Residents Association Limited | Households | 2005 |
| Mergic Group Ltd | Professional & scientific | 2021 |
| Meridian Brands Group Ltd | Wholesale & retail | 2026 |
| Meridian Centre Services Limited | Professional & scientific | 2025 |
| Meridian South Block H Management Limited | Households | 2006 |
| Meridian South Blocks a & B Management Limited | Households | 2005 |
| Meridian South Blocks C and D Management Limited | Households | 2003 |
| Meridian South Management Limited | Households | 2003 |
| Meridian Wills & Trusts Ltd | Other services | 2014 |
| Merlins Cave Management Company Limited | Households | 1999 |
| Merlins Court RTM Limited | Households | 2006 |
| Mero Sale Ltd | Wholesale & retail | 2021 |
| Merohub Ltd | Information & communication | 2019 |
| Merrymaid Public House Limited | Hospitality | 2005 |
| Merryweather Court (Reigate) Management Limited | Households | 2010 |
| Mersey Technical Services Ltd | Professional & scientific | 2007 |
| Merstham Ltd | Hospitality | 2016 |
| Merston House Management Limited | Households | 2006 |
| Merston Manor Management Company Limited | Households | 2022 |
| Merton Autos Ltd | Wholesale & retail | 2019 |
| Merton Builders Ltd | Construction | 2023 |
| Merton House Residents Association Limited | Hospitality | 1986 |
| Merton Road Properties Limited | Real estate | 2015 |
| Mertoninns Limited | Hospitality | 2025 |
| Meru Investments Ltd | Real estate | 2017 |
| Merza Catering Ltd | Hospitality | 2025 |
| Mesal Assets Ltd | Professional & scientific | 2023 |
| Meta Developers Ltd | Construction | 2021 |
| Metabolic, Endocrine and Diabetes Services (Meds-Uk) Ltd | Health & social care | 2022 |
| Metabolight Ltd | Administrative & support | 2020 |
| Metal Railings London Ltd | Manufacturing | 2026 |
| Metalworks Freehold Limited | Households | 2022 |
| Metaquartz Ltd | Wholesale & retail | 2025 |
| Metchem Specialities Limited | Wholesale & retail | 1995 |
| Metehan Properties Ltd | Real estate | 2018 |
| Metric Administration Services Limited | Administrative & support | 2015 |
| Metric Builds Installations Limited | Construction | 2024 |
| Metric Investments Limited | Real estate | 2014 |
| Metric Works Ltd | Manufacturing | 2024 |
| Metriqa Steel Ltd | Manufacturing | 2022 |
| Metro Build London Limited | Construction | 2024 |
| Metro Homes & Property Developments Limited | Professional & scientific | 2006 |
| Metro Multi Media Limited | Information & communication | 2017 |
| Metroglaze (London) Ltd | Construction | 2007 |
| Metrolane Limited | Other services | 2022 |
| Metromoves Limited | Real estate | 2025 |
| Metropolis Financial Platforms Limited | Information & communication | 2007 |
| Metropolis Global Limited | Information & communication | 2003 |
| Metropolis Group Holdings Limited | Information & communication | 2013 |
| Metropolis Group Limited | Financial services | 2017 |
| Metropolis International Group Ltd | Information & communication | 1994 |
| Metropolis International Limited | Extraterritorial | 2015 |
| Metropolitan Croydon Ltd | Construction | 2019 |
| Metropolitan Scaffolding Ltd | Wholesale & retail | 2006 |
| Metropolitan Waste Limited | Professional & scientific | 2006 |
| Metsab Auctions Ltd | Wholesale & retail | 2024 |
| Mewburn Hayward Limited | | 1978 |
| Mews Residents Association (Worthing) Limited(The) | Households | 1963 |
| Mezlocksmith Ltd | Administrative & support | 2026 |
| Mezzo Litro Ltd | Hospitality | 2012 |
| MF Creative & Style Ltd | Arts & recreation | 2023 |
| MF Optometry Ltd | Professional & scientific | 2017 |
| MFA Services London Limited | Construction | 2020 |
| MFP Audit Consultancy Limited | Professional & scientific | 2007 |
| MFR Builder Ltd | Construction | 2022 |
| MFR Properties & Sales Ltd | Real estate | 2026 |
| MG Davidson Holding Limited | Real estate | 2025 |
| MG Pathways CIC | Other services | 2025 |
| MG Serenity Care Limited | Health & social care | 2024 |
| MGA Abacus Limited | Professional & scientific | 2024 |
| MGD Services Limited | Transport & logistics | 2015 |
| MGE London Ltd | Construction | 2026 |
| MGT Enterprise Ltd | Education | 2010 |
| Mh-Apex Limited | Professional & scientific | 2026 |
| MHA Healthcare Ltd | Professional & scientific | 2017 |