| Michael Rose Clothing Ltd | Wholesale & retail | 2024 |
| Michaela Whyte Stationery Ltd | Manufacturing | 2026 |
| Michka Ltd | Wholesale & retail | 2024 |
| Mico Construction Ltd | Construction | 2019 |
| Micro Fiber Ltd | Construction | 2026 |
| Micro Finish Grinding (U.K.) Limited | Manufacturing | 1990 |
| Micro Interlock Academy Ltd | Education | 2025 |
| Micromax Consulting Ltd | Information & communication | 2011 |
| Mics and Lens Studios Ltd | Wholesale & retail | 2025 |
| Midbury Ltd | Wholesale & retail | 2016 |
| Midnight Peak Ltd | Construction | 2026 |
| Midnite Music Ltd | Information & communication | 2025 |
| MIG Asset Management Limited | Real estate | 2016 |
| Mighty Glorious Ltd | Health & social care | 2025 |
| Mignot Homes Ltd | Real estate | 2020 |
| Mijoco Limited | Other services | 2021 |
| Mikado Properties Ltd | Real estate | 2015 |
| Mike's Way Driving School Limited | Education | 2019 |
| Mila Construction Ltd | Manufacturing | 2018 |
| Milagroso LDN Ltd | Wholesale & retail | 2021 |
| Miles and Elliott Limited | Real estate | 2021 |
| Milestone Global Solutions Ltd | Administrative & support | 2016 |
| Milio 2007 Ltd | Transport & logistics | 2020 |
| Mill Europe LP | | 2017 |
| Millar Property Consultants Limited | Real estate | 2003 |
| Millendale Limited | Real estate | 1989 |
| Millennium Court Freehold Ltd | Households | 2025 |
| Milli CLO London Limited | Wholesale & retail | 2025 |
| Millionsbeautyhub Ltd | Other services | 2025 |
| Millsymac Limited | Information & communication | 2010 |
| Milon Lift Installation Ltd | Construction | 2019 |
| Mima's Place Ltd | Hospitality | 2021 |
| Mims Build Limited | Construction | 2025 |
| Mind Capsules Group Ltd | Information & communication | 2024 |
| Mind Connection Ltd | Health & social care | 2013 |
| Mindcraft Academy Ltd | Health & social care | 2026 |
| Mindful Management Ltd | Real estate | 2025 |
| Minerva Online Limited | Wholesale & retail | 2020 |
| Minitox UK Ltd | Wholesale & retail | 2020 |
| Mint Services Domestic Ltd | Administrative & support | 2024 |
| Mint Services Exterior Ltd | Administrative & support | 2024 |
| Minted FI Life Ltd | Wholesale & retail | 2025 |
| Min’S Retro & Vintage Clothing Company Ltd | Wholesale & retail | 2019 |
| MIO Beauty Company Limited | Other services | 2022 |
| MIR Construction UK Ltd | Construction | 2013 |
| Mira Coaching & Consulting Ltd | Professional & scientific | 2019 |
| Mira Umut Properties Ltd | Real estate | 2025 |
| Miracle & SI Ltd | Health & social care | 2023 |
| Miracle Tuition Ltd | Professional & scientific | 2020 |
| Miraclevr Limited | Administrative & support | 2025 |
| Miran Mirza Arbitration Chambers Limited | Professional & scientific | 2025 |
| Miras Silk Road Collective Ltd | Arts & recreation | 2023 |
| Mirevo Ltd | Real estate | 2021 |
| Miri Care Ltd | Public administration | 2022 |
| Mirian Devine Ltd | Health & social care | 2022 |
| Mirkesh Limited | Hospitality | 2011 |
| Miro Upminster Limited | Real estate | 2024 |
| Mirocan Limited | Hospitality | 2019 |
| Mirpolat Ltd | Real estate | 2020 |
| Miruma Consultants Ltd | Other services | 2018 |
| Mirzan Construction Ltd | Construction | 2020 |
| Misa Burger & Açaí Ltd | Hospitality | 2026 |
| Misaro Ltd | Real estate | 2019 |
| Mishem Property Ltd | Real estate | 2024 |
| Miss Bay Beauty Ltd | Wholesale & retail | 2025 |
| Misss Mustafa Ltd | Professional & scientific | 2024 |
| Misu Drylining Ltd | Construction | 2026 |
| Mitacell Ltd | Wholesale & retail | 2020 |
| Mitchell & Lillis Property Solutions Ltd | Real estate | 2023 |
| Mitra's Brow Bar Ltd | Other services | 2022 |
| MJ Clean Limited | Administrative & support | 2026 |
| Mjam Solutions Ltd | Transport & logistics | 2023 |
| MJD Communications Ltd | Extraterritorial | 2003 |
| MJJ Healthcare Services Ltd | Health & social care | 2023 |
| MJL Homes Limited | Real estate | 2018 |
| MJR Contracts Limited | Construction | 2016 |
| Mjro Ltd | Professional & scientific | 2025 |
| MJS Painting LLP | | 2025 |
| MJS Prop Ltd | Real estate | 2022 |
| MK Audio-Visual Elementz Limited | Information & communication | 2020 |
| MK Building & Decorating Ltd | Construction | 2025 |
| MK Business Solutions Ltd | Professional & scientific | 2009 |
| MK Constructions&Building Services Ltd | Construction | 2016 |
| MK Fencing Limited | Construction | 2019 |
| MK Kara Properties Ltd | Real estate | 2026 |
| MK Therapies Limited | Health & social care | 2021 |
| MK Translations & Services Limited | Professional & scientific | 2017 |
| MKA Estate Management Ltd | Wholesale & retail | 2023 |
| Mkarepart Limited | Wholesale & retail | 2021 |
| Mkeb Ltd | Real estate | 2022 |
| MKK Time Ltd | Hospitality | 2018 |
| Mklh Limited | Extraterritorial | 2021 |
| MKM House Construction Limited | Construction | 2025 |
| MKM LDN Ltd | Wholesale & retail | 2024 |
| Mksj Ltd | Information & communication | 2011 |
| ML Props Ltd | Information & communication | 2019 |
| ML Recruitment & Payroll Ltd | Administrative & support | 2019 |
| MLB Renovations Ltd | Construction | 2018 |
| Mlot Investments Limited | Real estate | 2026 |
| MM Contractors Limited | Construction | 2018 |