| Midrashai Ltd | Information & communication | 2016 |
| Midro Services Limited | Construction | 2023 |
| Midway Motors Ltd | Wholesale & retail | 2024 |
| Miista Limited | Manufacturing | 2010 |
| Miista Trading UK Limited | Wholesale & retail | 2014 |
| Mika Portfolio Limited | Real estate | 2023 |
| Mikaheel Ltd | Professional & scientific | 2021 |
| Mike Beard Medic Limited | Health & social care | 2015 |
| Mikey's Building Services Ltd | Construction | 2024 |
| Mil-Uk (2021) Limited | Information & communication | 2016 |
| Mile & UK Ltd | Construction | 2020 |
| Milk & LAB Ltd | Wholesale & retail | 2020 |
| Mill Hill Newsagents Limited | Wholesale & retail | 2021 |
| Mills Decorations Limited | Construction | 2021 |
| Mills Eyecare Limited | Wholesale & retail | 2010 |
| Mills Limited | Wholesale & retail | 1933 |
| Milpharm Limited | Wholesale & retail | 1997 |
| Milton International Limited | Wholesale & retail | 2019 |
| Mimbay Packaging Limited | Manufacturing | 2017 |
| Mind Rise Ltd | Health & social care | 2026 |
| Mind Setters Health Consult Ltd | Health & social care | 2025 |
| Mind Works International Limited | Professional & scientific | 2024 |
| MIND8 Limited | Information & communication | 2024 |
| Mini Miracles Ltd | Health & social care | 2018 |
| Minisoft UK Limited | Information & communication | 1997 |
| Minman Limited | Real estate | 2021 |
| Mintu & Co Limited | Real estate | 2014 |
| Mioara Limited | Construction | 2020 |
| Mirai Chemicals UK Ltd | Wholesale & retail | 2019 |
| Mirai GAS UK Ltd | Wholesale & retail | 2019 |
| Miropol Ltd | Construction | 2015 |
| Mirova Connect Limited | Information & communication | 2026 |
| Misbourne Meadows Residents Ltd. | Households | 1995 |
| Mishi Consultancy Ltd | Administrative & support | 2024 |
| Misprint Films Ltd | Information & communication | 2023 |
| Missionsgrowth Ltd | Professional & scientific | 2025 |
| Mitchell M Heating Services Ltd | Construction | 2023 |
| Mitral Systems Limited | Extraterritorial | 1984 |
| Mitrans Ltd | Transport & logistics | 2025 |
| Mitsubishi Heavy Industries Air-Conditioning Europe, Ltd. | Wholesale & retail | 2013 |
| Mittze Ltd | Extraterritorial | 2018 |
| Miva Group Limited | Professional & scientific | 2022 |
| Miva Wood Floors Ltd | Administrative & support | 2015 |
| Mixed Freight Transport Ltd | Wholesale & retail | 2022 |
| MJ / RMS Logistics Ltd | Wholesale & retail | 2024 |
| MJ Optics Limited | Health & social care | 2014 |
| Mj&P Ltd | Professional & scientific | 2023 |
| Mj's Fish Bar Limited | Hospitality | 2019 |
| MJF Golf Services Ltd | Wholesale & retail | 2025 |
| Mjfg Holding Limited | Financial services | 2024 |
| MJL Ranks INT Ltd | Professional & scientific | 2026 |
| MJN Business Services Limited | Professional & scientific | 2017 |
| MJP Properties Ltd | Real estate | 2019 |
| MJP Psych Ltd | Health & social care | 2024 |
| MJS Accounting Ltd | Professional & scientific | 2020 |
| MJS Constructors Ltd | Construction | 2019 |
| MK Cooling London Ltd | Other services | 2019 |
| MK Investments Limited | Professional & scientific | 2021 |
| MK Premises Ltd | Real estate | 2024 |
| MK Prestige Services Ltd | Transport & logistics | 2016 |
| Mkilleen Services Ltd | Arts & recreation | 2023 |
| MKL Education and Enterprises Ltd | Information & communication | 2025 |
| MKM Design & Construction Limited | Construction | 2014 |
| Mkmk Ltd | Professional & scientific | 2013 |
| Mlflf Limited | Arts & recreation | 2019 |
| MLS Construct Ltd | Construction | 2016 |
| MLS Decorating Ltd | Construction | 2025 |
| MM Kodua Infrastructure Consulting Services Limited | Information & communication | 2025 |
| MM Screws & Tools Construction Ltd | Construction | 2021 |
| Mmec Limited | Information & communication | 2016 |
| MMF Trading Ltd | Construction | 2020 |
| MMG Property Group Ltd | Real estate | 2024 |
| Mmkx Ltd | Wholesale & retail | 2026 |
| MMM Bookkeeping Ltd | Transport & logistics | 2025 |
| MMP Design Limited | Professional & scientific | 1988 |
| Mn&Z Ltd | Transport & logistics | 2017 |
| MNJ Singhkaur Limited | Transport & logistics | 2026 |
| MNM Analytics Limited | Construction | 2020 |
| MNM Fashion Ltd | Wholesale & retail | 2022 |
| MNS & Sons Enterprises Ltd | Transport & logistics | 2026 |
| Mnsq Capital Ltd | Real estate | 2022 |
| Moaning Kennels Limited | Agriculture & fishing | 2021 |
| Mobile Security Services Limited | Extraterritorial | 2025 |
| Mobile Tyre Giant Ltd | Administrative & support | 2017 |
| MOBILE9 Ltd | Information & communication | 2015 |
| Moda Consultancy Limited | Professional & scientific | 2025 |
| Moda Textile London Ltd | Wholesale & retail | 2021 |
| Modanoon Ltd | Wholesale & retail | 2018 |
| Modasa Roadways Limited | Transport & logistics | 2025 |
| Mode Media Limited | Other services | 2015 |
| Modern Studio Tiktok Ltd | Wholesale & retail | 2025 |
| Moderra Ltd | Construction | 2015 |
| Modular Van Solutions Ltd | Wholesale & retail | 2026 |
| Moga Construction Limited | Administrative & support | 2026 |
| Mogul Club Ltd | Administrative & support | 2016 |
| Mohamed’S Quality Foods Ltd | Hospitality | 2026 |
| Mohit 1 Limited | Construction | 2025 |
| Mohs Tech UK Ltd | Health & social care | 2020 |
| Molla Properties Ltd | Real estate | 2022 |
| Momentum Timing Ltd | Administrative & support | 2025 |