| Michael Border Holdings Limited | Administrative & support | 2023 |
| Michael Davies Films Ltd | Information & communication | 2007 |
| Michael Dixon Restoration Ltd | Manufacturing | 2024 |
| Michael Drake Architects Ltd | Professional & scientific | 2010 |
| Michael Harraway Cars Limited | Wholesale & retail | 2018 |
| Michael Harris Consulting Limited | Professional & scientific | 2009 |
| Michael Henry Financial Consulting Limited | Professional & scientific | 2021 |
| Michael House Association Limited | Education | 1953 |
| Michael Katsimihas Limited | Health & social care | 2014 |
| Michael Kennedy Associates Ltd | Administrative & support | 2014 |
| Michael Knight Surveyors Limited | Extraterritorial | 2015 |
| Michael Leonard Property Ltd | Real estate | 2008 |
| Michael Nicholas Estate Agents Limited | Real estate | 2006 |
| Michael Page Accounting Limited | Professional & scientific | 2009 |
| Michael Pearce Project Services Limited | Construction | 2014 |
| Michael R. Edwards Ltd | Administrative & support | 2026 |
| Michael Saunders Redland Limited | Health & social care | 2018 |
| Michael Straun Limited | Professional & scientific | 2014 |
| Michael W Rowe Funeral Directors Limited | Other services | 2016 |
| Michaela Dance and Drama Limited | Education | 2020 |
| Michaeltrans Ltd | Transport & logistics | 2013 |
| Michaelwood Dairy Goats Limited | Agriculture & fishing | 2012 |
| Michal M Service Ltd | Manufacturing | 2023 |
| Michal Nosal Ltd | Transport & logistics | 2015 |
| Michalik Properties Ltd | Real estate | 2025 |
| Micharth Limited | Health & social care | 2023 |
| Michele Lock (Occupational Therapy) Ltd | Health & social care | 2012 |
| Michelin House Development Limited | Construction | 1985 |
| Michelin House Investment Company Limited | Construction | 1989 |
| Michelle YAM Ltd | Real estate | 2020 |
| Michopat Blessed Limited | Health & social care | 2015 |
| Mick Connaire Limited | Information & communication | 2004 |
| Mickleburgh Limited | Wholesale & retail | 1948 |
| Micolly Ltd | Real estate | 2019 |
| Micrima Limited | Professional & scientific | 2005 |
| Micro-Flexitronics Limited | Manufacturing | 1996 |
| Microbial Technologies Limited | Professional & scientific | 2015 |
| Microcement South East Limited | Construction | 2021 |
| Microcharge Limited | Wholesale & retail | 2017 |
| Microcosm Limited | Information & communication | 1980 |
| Microencapsulation Services Ltd | Professional & scientific | 2023 |
| Microflown Avisa UK Ltd | Public administration | 2019 |
| Microgrid Foundry Limited | Energy | 2019 |
| Microsegment Consulting Ltd | Information & communication | 2020 |
| Microsol Ltd | Professional & scientific | 2022 |
| Microwave Amps Ltd | Manufacturing | 1989 |
| Microwide Limited | Real estate | 1997 |
| MID & West IFA Limited | Financial services | 2009 |
| Mid-West Animal Health Ltd. | Professional & scientific | 1994 |
| Midas Bars Limited | Hospitality | 2004 |
| Midas Construction UK Limited | Construction | 2005 |
| Midas G & E Properties Limited | Construction | 2005 |
| Midas Global (USA) Limited | Administrative & support | 2019 |
| Midas Global Executive Search Limited | Administrative & support | 2019 |
| Midas JV Limited | Financial services | 2007 |
| Midas Property Solutions Limited | Real estate | 2010 |
| Midas Telecom Limited | Hospitality | 2000 |
| Midboard Limited | Manufacturing | 2009 |
| Middle 8 Consultants Limited | Professional & scientific | 2013 |
| Middle 8 Holdings Limited | Wholesale & retail | 2020 |
| Middle Creek Limited | Education | 2025 |
| Middle Distance Product Ltd | Manufacturing | 2020 |
| Middle Farms Limited | Agriculture & fishing | 2004 |
| Middle Hall Ltd | Health & social care | 2025 |
| MIDDLE13 Ltd | Professional & scientific | 2017 |
| Middlecombe Nursery Limited | Agriculture & fishing | 2007 |
| Midford Logistics Ltd | Transport & logistics | 2019 |
| Midforest Veterinary Practice Limited | Extraterritorial | 2005 |
| Midknight Limited | Manufacturing | 2026 |
| Midland Commercial Ltd | Real estate | 2006 |
| Midland Energy Assessors Ltd | Other services | 2023 |
| Midland Properties (Bristol) Limited | Construction | 2002 |
| Midland Spinner Limited | Hospitality | 2019 |
| Midland Terrace Ltd | Households | 2017 |
| Midmann Ltd | Health & social care | 2025 |
| Midnight Moss Limited | Information & communication | 2026 |
| Midsomer Developments Limited | Construction | 2007 |
| Midsomer Dispensing Ltd | Health & social care | 2011 |
| Midtone Ltd | Manufacturing | 2020 |
| Midway Limited | Professional & scientific | 2023 |
| Midway Projects Limited | Construction | 2002 |
| Midwife Millar Limited | Health & social care | 2024 |
| Midwood Properties (SW) Limited | Real estate | 2016 |
| MIE MIE Trading Ltd | Wholesale & retail | 2020 |
| Miety Stone Ltd | Administrative & support | 2007 |
| Migdad Take Away Ltd | Hospitality | 2024 |
| Might and Main Ltd | Professional & scientific | 2020 |
| Mightplus Limited | Real estate | 2000 |
| Mighty Griffin Recruitment Ltd | Administrative & support | 2020 |
| Mighty JOT Ltd | Arts & recreation | 2023 |
| Mightyclan Limited | Information & communication | 2023 |
| Migrant's Bureau CIC | Professional & scientific | 2019 |
| Migration Forensics Limited | Information & communication | 2015 |
| MIH BS3 Ltd | Real estate | 2026 |
| Mihaela Services Ltd | Health & social care | 2017 |
| Mihai Express Ltd | Transport & logistics | 2021 |
| Miint Marketing Ltd | Professional & scientific | 2019 |
| Miint Money Limited | Extraterritorial | 2026 |
| Mijo Krish Infotech Limited | Information & communication | 2021 |
| Mijoca Ltd | Hospitality | 2018 |