| MD Psychology Services Limited | Health & social care | 2026 |
| MD Wigs Ltd | Other services | 2026 |
| MDL Lighting UK Ltd | Extraterritorial | 2023 |
| ME Investments (London) Ltd | Real estate | 2020 |
| ME Scenery Ltd | Construction | 2019 |
| Meale (U K) Electric Co., Ltd | Extraterritorial | 2021 |
| MEANT2BEAN... Ltd | Hospitality | 2018 |
| Meantime Travel Limited | Administrative & support | 2020 |
| Mears and Jackson Limited | Other services | 2012 |
| Mears Family Funerals Limited | Other services | 2026 |
| Mears Services Limited | Other services | 2025 |
| Meat Mood Ltd | Hospitality | 2026 |
| Meat People Limited | Extraterritorial | 2011 |
| Mebeauty Skincare Ltd | Manufacturing | 2022 |
| Mechael Ting Limited | Extraterritorial | 2023 |
| Mechsens Solutions Limited | Manufacturing | 2025 |
| MED Bar & Grill Limited | Hospitality | 2017 |
| Mediamz Co., Ltd | Wholesale & retail | 2020 |
| Medic Derma Research Limited | Wholesale & retail | 2022 |
| Medical Express Ultimate Care Services Limited | Health & social care | 2015 |
| Medimeasures Healthcare Limited | Health & social care | 2018 |
| Medising CIC | Health & social care | 2019 |
| Mediskin Beckenham Ltd | Other services | 2026 |
| Medland Holdings Limited | Real estate | 2026 |
| Medlere Limited | Manufacturing | 2023 |
| Medo Decor Ltd. | Manufacturing | 2021 |
| Medsenso Ltd | Manufacturing | 2023 |
| Medsolution Tech Ltd | Manufacturing | 2016 |
| Meek Trade Ltd | Manufacturing | 2025 |
| Meeno International Trade Co., Limited | Wholesale & retail | 2023 |
| Meet the Future Ltd | Information & communication | 2020 |
| Meets Toys Co., Ltd | Extraterritorial | 2020 |
| Megbond IMP and EXP Co., Ltd. | Wholesale & retail | 2023 |
| MEI Flower International Holdings Ltd | Wholesale & retail | 2021 |
| MEI JIN SI Trading Co., Ltd | Extraterritorial | 2022 |
| Meilan Muller Electric Co., Ltd | Manufacturing | 2021 |
| Meilong International Co., Ltd | Wholesale & retail | 2023 |
| Meimiao Trade Ltd | Wholesale & retail | 2023 |
| Meisaiteng Industry Co., Limited | Manufacturing | 2016 |
| Meisen Wooden Products Co., Ltd | Extraterritorial | 2019 |
| Meister Group Chemical Co., Limited | Mining & quarrying | 2025 |
| Meita International Sourcing Limited | Wholesale & retail | 2024 |
| Melecc (Hongkong) Industries Limited | Extraterritorial | 2019 |
| Melegi Industry Limited | Extraterritorial | 2023 |
| Melida Industrial Limited | Extraterritorial | 2023 |
| Melinda Import and Export Co., Limited | Extraterritorial | 2024 |
| Meline Trading Co., Ltd | Manufacturing | 2025 |
| Mellisong Group Limited | Extraterritorial | 2016 |
| Mello Events Limited | Education | 2014 |
| Meloconnection Limited | Construction | 2022 |
| Melon Seed Limited | Other services | 2010 |
| Melove UA Int'L Group Limited | Extraterritorial | 2014 |
| Meltemia Properties Ltd | Real estate | 2025 |
| Membracon Water (UK) Limited | Manufacturing | 2022 |
| Memoe Holdings Ltd | Financial services | 2019 |
| Memory & Brain Health Limited | Professional & scientific | 2017 |
| Mengyue (UK) London Co., Ltd | Wholesale & retail | 2025 |
| MER (Tian JIN) Marine Service Co Ltd | Manufacturing | 2024 |
| Merck Valve&Controls Limited | Manufacturing | 2022 |
| Mercrepairs Limited | Wholesale & retail | 2008 |
| Mercury Hera Limited | Financial services | 2021 |
| Meritus Trading Group Ltd | Manufacturing | 2025 |
| Mesch SIC Co., Ltd | Manufacturing | 2019 |
| Mesida Trade Co., Ltd | Extraterritorial | 2021 |
| Message Design Limited | Professional & scientific | 2014 |
| Meta Diagram Tech Ltd | Wholesale & retail | 2022 |
| Meta Granite Design UK Ltd | Other services | 2020 |
| Meta Leone Limited | Information & communication | 2025 |
| Metacrypto Limited | Information & communication | 2021 |
| Metainfo Ltd | Information & communication | 2022 |
| Metal Awards Industrial Co., Ltd | Extraterritorial | 2014 |
| Metal Science and Technology Limited | Extraterritorial | 2018 |
| Metamethod Limited | Information & communication | 2021 |
| Metavisa Foundation | Financial services | 2022 |
| Metery Technology Limited | Extraterritorial | 2021 |
| Metro Grace Enterprise Ltd | Extraterritorial | 2014 |
| Metro Kebab & Pizza Ltd | Hospitality | 2025 |
| Metrode Products Limited | Manufacturing | 2024 |
| Metron Industrial Limited | Wholesale & retail | 2024 |
| Metta Movement Ltd | Health & social care | 2024 |
| Mewis Associates Limited | Professional & scientific | 2011 |
| Mffs Solutions Ltd | Professional & scientific | 2014 |
| MFH2 Ltd | Financial services | 2017 |
| Mfls Investments Ltd | Real estate | 2018 |
| MFX Bright Industry Co., Ltd | Extraterritorial | 2013 |
| MG and J Commercial Consultants Limited | Administrative & support | 2009 |
| MG Atzori Consultants Ltd | Professional & scientific | 2002 |
| MG Landscape Gardeners Ltd | Administrative & support | 2025 |
| MG Tech London Ltd | Wholesale & retail | 2023 |
| MGA Recruitment Limited | Administrative & support | 1994 |
| MGF Engineering Limited | Manufacturing | 2003 |
| MGM Properties Investments Ltd | Professional & scientific | 2017 |
| MGP Cooling 247 Ltd | Energy | 2025 |
| MGS GAS Heating Limited | Construction | 2007 |
| MGS SKI Limited | Administrative & support | 2003 |
| MGT Builders Ltd | Construction | 2022 |
| MHH Group Limited | Extraterritorial | 2017 |
| MHM Creative Limited | Information & communication | 2020 |
| MHS Associates Holding Company Limited | Financial services | 2023 |
| MHS Associates Limited | Financial services | 1994 |