| Melike for Trade Ltd | Wholesale & retail | 2021 |
| Melinda Limited | Extraterritorial | 2020 |
| MELL123 Limited | Agriculture & fishing | 2015 |
| Mellwood Stables LLP | | 2015 |
| Melly Medium Ltd | Information & communication | 2024 |
| Melon Games Limited | Information & communication | 2022 |
| Melsonia Ltd | Information & communication | 2021 |
| Melville Family Holdings Limited | Construction | 2015 |
| Melville Investments Limited | Construction | 2015 |
| Mel’On Cosmetics Ltd | Wholesale & retail | 2025 |
| Memory Robin Ltd | Information & communication | 2026 |
| MEN Only Limited | Extraterritorial | 2011 |
| Mengia E Bevi Vino Torino Limited | Wholesale & retail | 2023 |
| Menk for Trade Ltd | Wholesale & retail | 2024 |
| Menopause CBD Ltd | Wholesale & retail | 2020 |
| Menshn Ltd | Extraterritorial | 2012 |
| Menzies Kennedy Productions Ltd | Information & communication | 2016 |
| Meraki Harrogate Ltd | Other services | 2017 |
| Merbeth Services Limited | Administrative & support | 2025 |
| Merbethproperties Limited | Real estate | 2023 |
| Mercatus Research Ltd | Professional & scientific | 2015 |
| Merchant Medical Limited | Extraterritorial | 2025 |
| Merchant Solutions Limited | Extraterritorial | 2025 |
| Merchant West Limited | Extraterritorial | 2025 |
| Merci for Business Servicess Ltd | Information & communication | 2024 |
| Mercury Property Holdings Ltd | Real estate | 2016 |
| Merdeka Homes Limited | Real estate | 2021 |
| Meridian Personnel Ltd | Administrative & support | 2018 |
| Merlin Burrows Limited | Professional & scientific | 2015 |
| Merlindown Limited | Professional & scientific | 2015 |
| Merlins Dvds Limited | Information & communication | 2020 |
| Messor Ltd. | Professional & scientific | 2021 |
| Metalinear Limited | Professional & scientific | 2016 |
| Metcon Ltd | Construction | 2026 |
| Metnor Holdings Limited | Other services | 2019 |
| Metric Holdings Ltd | Arts & recreation | 2026 |
| Metric Performance Ltd | Arts & recreation | 2026 |
| Metrica Environmental Consulting Limited | Professional & scientific | 2022 |
| Metro Locksmiths Ltd | Administrative & support | 2012 |
| Metroport Limited | Wholesale & retail | 2014 |
| Mewp Ltd | Professional & scientific | 2011 |
| MEY Trade Limited | Wholesale & retail | 2016 |
| Meyhem Ltd | Extraterritorial | 2012 |
| Mfpm Limited | Professional & scientific | 2012 |
| MG IP Ltd | Administrative & support | 2019 |
| MGH Power Consulting Limited | Professional & scientific | 2019 |
| MGP Asset Management Ltd | Wholesale & retail | 2023 |
| MGR Recruitment Ltd | Administrative & support | 2018 |
| MGS Hospitality Ltd | Hospitality | 2021 |
| MGT Automotive Ltd | Professional & scientific | 2016 |
| MGT Software Limited | Information & communication | 2016 |
| MGW Business Services Ltd | Professional & scientific | 2014 |
| MH Location Services Ltd | Administrative & support | 2022 |
| MH123 Limited | Extraterritorial | 2016 |
| MHK Timber and Veneers Limited | Wholesale & retail | 2012 |
| MHP Technical Limited | Professional & scientific | 2008 |
| MI Khushi Ltd | Hospitality | 2025 |
| MIC Therapy Services Ltd | Health & social care | 2024 |
| Michael Bower Limited | Administrative & support | 2004 |
| Michael Mcmeeken Ltd | Real estate | 2017 |
| Michelle Beckett Ltd | Professional & scientific | 2024 |
| Mickle Hill Wind Farm Limited | Energy | 2024 |
| Mictopia Limited | Manufacturing | 2024 |
| MID Century Group Ltd | Wholesale & retail | 2020 |
| MIDA5 Ltd | Extraterritorial | 2020 |
| Midas Electronic Consultants Limited | Manufacturing | 1989 |
| Midasmotion Limited | Manufacturing | 2003 |
| Midday Ltd | Health & social care | 2025 |
| Middlemiss Properties Ltd | Real estate | 2022 |
| Middleton Business Services Limited | Professional & scientific | 2023 |
| Midge Licensing Limited | Manufacturing | 2021 |
| Midnight Sun Limited | Real estate | 2023 |
| Mike Alderson Consultancy Ltd | Education | 2024 |
| Mike and Dave Holdings Limited | Financial services | 2017 |
| Mike and Dave Properties Limited | Real estate | 2019 |
| Mike Woodhall Consulting Ltd | Professional & scientific | 2024 |
| Mikey's Way Sandwich Company Ltd | Hospitality | 2025 |
| Mile END Investment Limited Partnership | | 2010 |
| Mile END Limited Partnership | | 2007 |
| Mileendproperty Limited | Real estate | 2021 |
| Miles Away Media Limited | Arts & recreation | 2022 |
| Miles Baul & Sons Limited | Agriculture & fishing | 2014 |
| Military Wines Limited | Hospitality | 2012 |
| MILL1E Limited | Extraterritorial | 2020 |
| Millbeck Limited | Extraterritorial | 2011 |
| Millcraft Enterprises Limited | Extraterritorial | 2014 |
| Millennium FM Limited | Extraterritorial | 2026 |
| Miller and Lewis Limited | Extraterritorial | 2026 |
| Millie Cummings Ltd | Professional & scientific | 2011 |
| Million Burger Ltd | Hospitality | 2025 |
| Million Enterprises Limited | Extraterritorial | 2025 |
| Million Investment Group Limited | Financial services | 2025 |
| Million Limited | Extraterritorial | 2026 |
| Millionhairs Ltd | Other services | 2002 |
| Millpark Construction Limited | Construction | 2011 |
| Millpark Properties Limited | Real estate | 2015 |
| Mills Hospitality and Events Limited | Hospitality | 2026 |
| Mills Motors (Harrogate) Limited | Wholesale & retail | 2025 |
| Millstone GEO Services Ltd | Construction | 2022 |
| Milo Associates Limited | Health & social care | 2014 |