| Mena Direct Ltd | Professional & scientific | 2008 |
| Meniscus Partners Limited | Professional & scientific | 1998 |
| Mensahmedia Ltd | Information & communication | 2019 |
| Mental Health & Adhd Specialists Ltd | Health & social care | 2015 |
| Mercurial Systems Limited | Construction | 2006 |
| Mercury Ortho Limited | Health & social care | 2017 |
| Merevale House Management Limited | Households | 2015 |
| Meridean Overseas Consultants Limited | Wholesale & retail | 2024 |
| Meridyna Limited | Wholesale & retail | 2023 |
| Meritus Associates Ltd | Professional & scientific | 2015 |
| Merlin Cctv Ltd | Administrative & support | 2021 |
| Merlin Family Investments Limited | Financial services | 2026 |
| Merrin Electrical Limited | Construction | 2013 |
| Mervyn J Ewart (Decorators) Ltd | Construction | 2004 |
| Metaforlearning CIC | Education | 2021 |
| Metal Marine Limited | Extraterritorial | 1990 |
| Metaphor Trading Ltd | Wholesale & retail | 2023 |
| Metascope Public Relations Ltd | Professional & scientific | 2023 |
| Metasys Solutions Limited | Professional & scientific | 2023 |
| Metis Consultants EOT Limited | Administrative & support | 2025 |
| Metis Consultants Limited | Professional & scientific | 2009 |
| Metray Limited | Professional & scientific | 2011 |
| Metriculous Ltd | Information & communication | 2017 |
| Metro House Estate Limited | Real estate | 2025 |
| Mewsgreen Properties Limited | Real estate | 1999 |
| Mezem Ltd | Hospitality | 2025 |
| Mezzanine Capital UK Limited | Financial services | 2020 |
| MF Cira Limited | Real estate | 2020 |
| Mf&P Properties Ltd | Real estate | 2026 |
| MFA Building Control Limited | Construction | 2003 |
| MFA Holdings (Derby) Ltd | Financial services | 2020 |
| Mfgr Limited | Professional & scientific | 2014 |
| MFR Associates Limited | Real estate | 2017 |
| MGF Consultants Limited | Professional & scientific | 2019 |
| Mial Coachbuilders Limited | Manufacturing | 2003 |
| Miava Capital Ltd | Public administration | 2020 |
| Michael GUY Electrical Limited | Construction | 2013 |
| Michael Jones Architects Limited | Professional & scientific | 2013 |
| Michael's Shoe Repairs Limited | Other services | 2013 |
| Michelle Mctaggart Hairdressing Limited | Other services | 2003 |
| Mick Kilroy Services Ltd | Administrative & support | 2021 |
| Micopia Limited | Wholesale & retail | 2023 |
| Mid-Tech Solutions Ltd | Information & communication | 2025 |
| Middle Caves Ltd | Agriculture & fishing | 2003 |
| Middleton Lodge Building Services Limited | Construction | 2012 |
| Middleton Lodge Estates Limited | Administrative & support | 2001 |
| Middleton Lodge Holdings Limited | Financial services | 2022 |
| Midhurst Russell LLP | | 2015 |
| Midiswitch Limited | Manufacturing | 2024 |
| Midland Industrial Flooring Limited | Manufacturing | 1982 |
| Midland Industrial Group Limited | Professional & scientific | 1995 |
| Midland Industrial Systems Ltd. | Manufacturing | 1996 |
| Midlife Productions Limited | Information & communication | 2012 |
| Midrange Systems Limited | Manufacturing | 2011 |
| MIF Composites Ltd | Manufacturing | 2021 |
| Migb Limited | Information & communication | 2022 |
| Mignonette Bistro Ltd | Hospitality | 2023 |
| Mike Wong Fitness Limited | Arts & recreation | 2017 |
| Mikico Limited | Information & communication | 2013 |
| Miksasi Holdings Ltd | Wholesale & retail | 2023 |
| Milamed Limited | Health & social care | 2023 |
| Milecastle Projects Limited | Professional & scientific | 2023 |
| Military Craftmanship Ltd | Professional & scientific | 2023 |
| Mill Park (Richmond) Limited | Real estate | 2013 |
| Mill Poultry Limited | Agriculture & fishing | 1995 |
| Millais Movement Ltd | Arts & recreation | 2025 |
| Millennial Technologies Ltd | Information & communication | 1997 |
| Millennial Technologies Services Limited | Administrative & support | 2020 |
| Millennium Print Limited | Professional & scientific | 2023 |
| Millislearn Academy Limited | Education | 2025 |
| Milllogic Limited | Administrative & support | 2025 |
| Milner Ecology Limited | Professional & scientific | 2010 |
| Milo Logistics Limited | Arts & recreation | 2013 |
| Mimeto Ltd | Manufacturing | 2024 |
| Mimosa Wellness Ltd | Health & social care | 2025 |
| Mindberry AI Limited | Health & social care | 2016 |
| Mindberry Group Limited | Information & communication | 2016 |
| Mindblasts Ltd. | Wholesale & retail | 2019 |
| Mindful Brands Ltd | Wholesale & retail | 2021 |
| Mineaoil Limited | Professional & scientific | 2015 |
| Minesoft Ltd | Information & communication | 1996 |
| Mini & ME Active Ltd | Other services | 2025 |
| Minicase Ltd | Arts & recreation | 2018 |
| Mint Group Ltd | Construction | 2015 |
| Miplus Limited | Wholesale & retail | 2025 |
| Mira Cares Limited | Health & social care | 2020 |
| Mira Flavour Limited | Hospitality | 2022 |
| Mirabello Estate Ltd | Agriculture & fishing | 2020 |
| Miramar Executive Search Limited | Administrative & support | 2009 |
| Miramar Global Holdings Limited | Financial services | 2017 |
| Mirandus Properties Ltd | Real estate | 2019 |
| Mirandus Tours Ltd | Administrative & support | 2014 |
| Mirror X Ltd | Administrative & support | 2026 |
| Mishika Enterprises Limited | Health & social care | 2012 |
| Miskin Maternity Limited | Health & social care | 2014 |
| Mission Autonomy Ltd | Manufacturing | 2021 |
| Mister MEN Limited | Arts & recreation | 2004 |
| Mitra & Katzinski Limited | Health & social care | 2026 |
| Mitre PUB Partnership Limited | Hospitality | 2015 |
| MJ Golf Enterprises Ltd | Arts & recreation | 2018 |