| Miran Property & Developments Ltd | Real estate | 2026 |
| Mirel's Aircraft Ltd | Manufacturing | 2026 |
| Miriam Elisa Ltd | Manufacturing | 2024 |
| Mirussell Ltd | Education | 2004 |
| MIS Local Government Systems Limited | Information & communication | 2001 |
| Misgo Limited | Health & social care | 2025 |
| MISHAKA9412 Lamination Ltd | Manufacturing | 2025 |
| Misquitta Holdings Limited | Financial services | 2018 |
| Miss Carlysle and Co Ltd | Professional & scientific | 2025 |
| Miss Doom Media Limited | Information & communication | 2022 |
| Miss ELI Ltd | Wholesale & retail | 2020 |
| Mission (2025) Ltd | Professional & scientific | 2022 |
| Mission (2026) Ltd | Professional & scientific | 2021 |
| Mission Computers Ltd | Extraterritorial | 2014 |
| Mission Initiative Ltd | Professional & scientific | 2025 |
| Mission Therapeutics Limited | Professional & scientific | 2011 |
| Mission: Explore Ltd | Arts & recreation | 2025 |
| Missnk Ltd | Wholesale & retail | 2026 |
| Mistras E T S Limited | Professional & scientific | 2011 |
| Mistras Group Limited | Professional & scientific | 1983 |
| Mistras Properties Limited | Real estate | 2011 |
| Mistras Tekra Limited | Professional & scientific | 2006 |
| Misty Meadows Flats Limited | Real estate | 1986 |
| Misty Meadows Freehold Limited | Real estate | 2005 |
| MISUAVIATIE59 Ltd | Manufacturing | 2025 |
| MIT Nail Spa Ltd | Other services | 2023 |
| Mita Global Limited | Health & social care | 2021 |
| Mitoexport Limited | Professional & scientific | 2025 |
| Mittfit Limited | Arts & recreation | 2022 |
| Miumoto Ltd | Manufacturing | 2025 |
| Miwtech Ltd | Wholesale & retail | 2019 |
| Mixdat Ltd | Professional & scientific | 2007 |
| MIZ Handyman at Your Services Ltd | Construction | 2019 |
| Mizan Research and Education | Education | 2016 |
| Mizon Thatchers Ltd | Construction | 2026 |
| MJ BET Holdings Limited | Other services | 2024 |
| MJA Medical Services Limited | Health & social care | 2018 |
| MJA Properties Group Limited | Other services | 2018 |
| Mjctc Limited | Construction | 2009 |
| Mjdk Solutions Limited | Information & communication | 2007 |
| Mjh-It Ltd | Information & communication | 2015 |
| Mjkj Limited | Professional & scientific | 2013 |
| MJM Tech Limited | Administrative & support | 2016 |
| MJP Cleaning Ltd | Administrative & support | 2024 |
| Mjprojects Ltd | Construction | 2022 |
| MJR Auto Salvage Ltd | Water & waste | 2019 |
| MJS Assoc Ltd | Professional & scientific | 2022 |
| Mjstapleh Limited | Professional & scientific | 2024 |
| MJW Haverhill Limited | Financial services | 2019 |
| MK Accurate Building Solutions Ltd | Construction | 2023 |
| MK Aquarius Ltd | Manufacturing | 2025 |
| MK Cambridge Limited | Professional & scientific | 2017 |
| MK Carbon Ltd | Manufacturing | 2022 |
| MK Plastering Limited | Construction | 2019 |
| MK Prime Properties Ltd | Real estate | 2025 |
| MK Smart Property Investments Limited | Real estate | 2016 |
| MKA Property Ltd | Real estate | 2016 |
| Mkay Consultancy Limited | Public administration | 2018 |
| Mkay Investments Ltd | Real estate | 2020 |
| MKB Aviation Limited | Manufacturing | 2015 |
| MKD & DJ Holdings Limited | Professional & scientific | 2002 |
| MKD & DJ Property Limited | Real estate | 2007 |
| Mkio Ltd | Information & communication | 2022 |
| Mkmb Ltd | Wholesale & retail | 2025 |
| MKO Logistics Ltd | Transport & logistics | 2021 |
| MKY Technology Ltd | Extraterritorial | 2015 |
| ML & RW Intertrade (UK) Co., Limited | Extraterritorial | 2012 |
| ML Partners LLP | | 2002 |
| ML Roofing Services Limited | Construction | 2019 |
| MLO Installations Ltd | Construction | 2020 |
| MLP Consultancy Limited | Arts & recreation | 2000 |
| Mlts Limited | Professional & scientific | 2003 |
| MM Aircraft Maintenance Ltd | Manufacturing | 2020 |
| MM Management Consulting Ltd | Professional & scientific | 2022 |
| MM Powerplus Limited | Manufacturing | 2025 |
| MM Services (South East) Limited | Construction | 2012 |
| MM Wealth Group Holdings Ltd | Financial services | 2022 |
| MM Wealth Ltd | Administrative & support | 1979 |
| MMA Trading Ltd | Wholesale & retail | 2013 |
| Mmaa Social Ltd | Wholesale & retail | 2017 |
| MMB Housing Ltd | Real estate | 2026 |
| Mmcyyy Ltd | Health & social care | 2019 |
| Mmed Medical Limited | Administrative & support | 2016 |
| MMJ Cars Ltd | Wholesale & retail | 2026 |
| MMJ Clinic Group Limited | Administrative & support | 2019 |
| MML Global Education Solutions Limited | Education | 2016 |
| MMM Hairdresser Limited | Other services | 2022 |
| Mmok Limited | Real estate | 2025 |
| Mmstancu Ltd | Manufacturing | 2026 |
| MNC Analysis Ltd | Information & communication | 2021 |
| MNC Haulage Limited | Transport & logistics | 2019 |
| Mnm.Structure.Mro Ltd | Manufacturing | 2025 |
| MO 0021A Ltd | Real estate | 2025 |
| MO 0021B Ltd | Real estate | 2025 |
| Mo's Smash Ltd | Hospitality | 2025 |
| Moat House Shining Light Productions Ltd | Information & communication | 2025 |
| Moats Way Equestrian Ltd | Agriculture & fishing | 2006 |
| MOAZ3641 Ltd | Manufacturing | 2025 |
| Mobas Limited | Information & communication | 2003 |
| Mobile Mate Ltd | Wholesale & retail | 2024 |