| MHX Computer Systems Limited | Information & communication | 2001 |
| Mia's of Sidcup Limited | Manufacturing | 2002 |
| Mia's Property Company Limited | Real estate | 2015 |
| Mianying Trading Co., Ltd | Extraterritorial | 2024 |
| Miaoshou Ltd | Wholesale & retail | 2024 |
| Miaoxin Culture Media Co., Ltd | Information & communication | 2021 |
| MIC Worldwide Trading Company Limited | Wholesale & retail | 2020 |
| Michael Darrell Limited | Administrative & support | 2020 |
| Michael Kitchen Ltd | Hospitality | 2025 |
| Michaelaj Limited | Construction | 2014 |
| Microtex International Trading Ltd | Wholesale & retail | 2022 |
| Microtronic Limited | Professional & scientific | 2004 |
| Midas (Farnborough) Limited | Education | 2013 |
| Midas (Lingfield) Limited | Education | 2015 |
| Midas (South Woodford) Limited | Education | 2006 |
| Midas Freehold Limited | Real estate | 2016 |
| Midlands Cabins Limited | Administrative & support | 2014 |
| Midudog Co., Ltd | Extraterritorial | 2020 |
| Mikadd Limited | Professional & scientific | 2022 |
| Mikel International Group Co., Ltd | Extraterritorial | 2022 |
| Mikombi Technology Limited | Wholesale & retail | 2026 |
| Mikoro Mining (Europe) Co., Ltd. | Extraterritorial | 2025 |
| Milan Supply Chain Development Ltd | Construction | 2023 |
| Milano Import and Export Co., Ltd | Wholesale & retail | 2023 |
| Mile Metal Products Co., Ltd | Extraterritorial | 2022 |
| Mile Transport Limited | Transport & logistics | 2026 |
| Milestone Mortgages Limited | Financial services | 2023 |
| Miletech Pharm Co., Ltd. | Extraterritorial | 2017 |
| Milian London Limited | Information & communication | 2017 |
| Milionato Marketing Limited | Professional & scientific | 2022 |
| Mill'Z Grill Ltd | Hospitality | 2020 |
| Millford (UK) Corporation Ltd. | Professional & scientific | 2008 |
| Millie Dutt Ltd | Health & social care | 2015 |
| Million Mile Stone Corporation Limited | Manufacturing | 2023 |
| Millisland Co., Ltd | Wholesale & retail | 2024 |
| Millk Ltd | Professional & scientific | 2017 |
| Millstream Financial Services Ltd | Financial services | 2009 |
| Milmiles Enterprises Ltd | Extraterritorial | 2017 |
| Milner Corporation Limited | Real estate | 1994 |
| Milos Machinery Co., Ltd | Extraterritorial | 2023 |
| Milson Ingredients Group Co., Ltd | Wholesale & retail | 2023 |
| Milstruct Limited | Construction | 2024 |
| Minap International Limited | Manufacturing | 2019 |
| Mind Body Soul Development Organisation Limited | Information & communication | 2013 |
| Mind Origin Limited | Wholesale & retail | 2021 |
| Mindofanarchitect Limited | Professional & scientific | 2026 |
| Mindry UK Ltd | Wholesale & retail | 2022 |
| Ming Trading Co Ltd | Extraterritorial | 2012 |
| Ming Yuhan Jewelry Co., Ltd. | Wholesale & retail | 2025 |
| Mingen Fashion Jewelry Co., Ltd. | Professional & scientific | 2021 |
| Minghai International Trade Co., Limited | Wholesale & retail | 2025 |
| Mingtai Medical Group Company Limited | Extraterritorial | 2018 |
| Mingyang Enterprise Co., Ltd | Wholesale & retail | 2022 |
| Mingyu Xing Industry Co., Ltd | Extraterritorial | 2024 |
| Minimio Limited | Manufacturing | 2015 |
| Minmoon LED Company Limited | Extraterritorial | 2019 |
| Minnos (London) Ltd | Hospitality | 2019 |
| Minovel Enterprises Limited | Extraterritorial | 2015 |
| Minshull Place Cottage RTM Company Limited | Households | 2012 |
| Minsky (London) Limited | Wholesale & retail | 2008 |
| Miny International Group Limited | Extraterritorial | 2021 |
| Miny Trading Co., Ltd | Extraterritorial | 2024 |
| Miracall Technology Co.,(U.K) Ltd. | Extraterritorial | 2009 |
| Miracle Trading Co., Ltd | Other services | 2021 |
| Mirage Tyre Co., Ltd. | Extraterritorial | 2015 |
| Mirana Consulting Services Limited | Professional & scientific | 2024 |
| Miranda Trading Co., Ltd | Extraterritorial | 2020 |
| Misa Packing Limited | Manufacturing | 2022 |
| Misco Clothing Co., Ltd | Wholesale & retail | 2022 |
| Miscuito Co., Ltd | Manufacturing | 2022 |
| Miso Beckenham Limited | Hospitality | 2017 |
| Miss Brow Aesthetics Limited | Other services | 2023 |
| Missing Button Limited | Professional & scientific | 2014 |
| Mission Estates Ltd | Real estate | 2025 |
| Mississippi Investments Limited | Real estate | 2025 |
| Mitamirri Limited | Information & communication | 2010 |
| Mitchell Roofing & Sons Limited | Construction | 2021 |
| Mitok LLP | | 2026 |
| Mituo Industrial Limited | Wholesale & retail | 2025 |
| Miulab Co., Ltd | Extraterritorial | 2016 |
| MIX & Bake Ltd | Manufacturing | 2016 |
| MJN Property Investment Limited | Real estate | 2016 |
| MJY Supermarket Equipment Supplies Ltd | Wholesale & retail | 2012 |
| MK Search & Selection Ltd | Administrative & support | 2023 |
| MK Weightloss Limited | Wholesale & retail | 2020 |
| MKL Construction Ltd | Construction | 2013 |
| MLH Property Investors Ltd | Real estate | 2025 |
| MLR Interim Consulting Limited | Other services | 2019 |
| Mmco Ltd | Arts & recreation | 2011 |
| Mmik Limited | Health & social care | 2015 |
| MMJ Catering Solutions Limited | Hospitality | 2025 |
| MMQ Motors Limited | Extraterritorial | 2014 |
| MMQ Property Management Ltd | Real estate | 2020 |
| Mmrc Associates Limited | Professional & scientific | 2022 |
| MNB Engineering Consulting Ltd | Professional & scientific | 2026 |
| MOB Film Holdings Limited | Professional & scientific | 2003 |
| MOB Sport Limited | Extraterritorial | 2013 |
| Moda Savoye Textile ( UK ) Limited | Extraterritorial | 2024 |
| Moderneon (London) Ltd. | Manufacturing | 1993 |
| Mods Luggage (UK) Limited | Wholesale & retail | 2014 |