| Meredithoh Limited | Professional & scientific | 2015 |
| Merging Rivers Grange Ltd | Health & social care | 2024 |
| Merging Rivers Holdings Ltd | Professional & scientific | 2024 |
| Meridian Partners Ltd | Administrative & support | 2013 |
| Meridian Secretaries Ltd | Administrative & support | 2013 |
| Merisa Dedja Limited | Other services | 2025 |
| Merlin Property Company Limited | Other services | 1959 |
| Merrayah Ltd | Manufacturing | 2022 |
| Merrill Consultants Limited | Information & communication | 2001 |
| Merwell Living Ltd | Wholesale & retail | 2024 |
| Mesut 2009 Ltd | Administrative & support | 2014 |
| Meta Trak UK Limited | Wholesale & retail | 2015 |
| Metabolic Health Pro Ltd | Health & social care | 2023 |
| Metbase Limited | Construction | 2013 |
| Metier Create Limited | Information & communication | 2013 |
| Metric Energy Limited | Professional & scientific | 2024 |
| Metric Ledger Limited | Wholesale & retail | 2019 |
| Metroland Enterprises Ltd | Professional & scientific | 2012 |
| Metromec Building Services Limited | Wholesale & retail | 1998 |
| Mettle Consulting Partners Limited | Professional & scientific | 2015 |
| Mexa Paint Ltd | Wholesale & retail | 2024 |
| MFE Projects Ltd | Professional & scientific | 2023 |
| MFH Inspection & Remediation Limited Liability Partnership | | 2024 |
| MG Consulting Ltd | Information & communication | 2023 |
| MG Florence Limited | Wholesale & retail | 2021 |
| MG Legal Consultancy Limited | Professional & scientific | 2017 |
| MGM & International Ltd | Transport & logistics | 2023 |
| MGM Bodywork Ltd | Manufacturing | 2023 |
| MGS DEV Ltd | Professional & scientific | 2024 |
| MH Bargains Mart Ltd | Wholesale & retail | 2021 |
| MHK Properties Ltd | Real estate | 2018 |
| Mhsn Ltd | Professional & scientific | 2024 |
| MHY Education Ltd | Wholesale & retail | 2020 |
| MIA House Construction Limited | Construction | 2024 |
| Miamisienna Ltd | Manufacturing | 2024 |
| Miatex Ltd | Information & communication | 2022 |
| Micah Neterling Ltd | Arts & recreation | 2012 |
| Michelle Palmer Designs Limited | Professional & scientific | 2025 |
| Michigan Energy Limited | Energy | 2020 |
| Middleton Financial Ltd | Financial services | 2014 |
| Midfree Residents Association Limited | Households | 1985 |
| Mightier Than the Sword Ltd | Administrative & support | 2019 |
| Migrant Advocacy Service Limited | Education | 2012 |
| Mikhail Moudrakovski Ltd | Professional & scientific | 2026 |
| Mikos Auto Technician Limited | Wholesale & retail | 2024 |
| Mila Home Design Ltd | Construction | 2021 |
| Milan Society Ltd | Health & social care | 2024 |
| Milcon Limited | Construction | 2025 |
| Mile High Consulting Limited | Professional & scientific | 2022 |
| Milestone Wealth Management Limited | Administrative & support | 2010 |
| Milevi Ltd | Wholesale & retail | 2025 |
| Milford Publishing Company Ltd | Information & communication | 2017 |
| Millbank Media Limited | Professional & scientific | 2006 |
| Millcon Limited | Professional & scientific | 2017 |
| Millennium Locksmiths Limited | Administrative & support | 2004 |
| Millennium Spa & Smile Ltd | Other services | 2025 |
| Millerchip Events Ltd | Hospitality | 2025 |
| Millpond Renewables Limited | Construction | 2025 |
| Mills IT Limited | Administrative & support | 2014 |
| Millward Investments Limited | Professional & scientific | 1997 |
| Milovi Consulting Ltd | Information & communication | 2013 |
| Mimosa 2018 Limited | Hospitality | 2018 |
| Minara (UK) Ltd | Professional & scientific | 1998 |
| Minco Mining Limited | Administrative & support | 2003 |
| Mind Blowing Properties Ltd | Real estate | 2020 |
| Mind in Kingston | Health & social care | 1999 |
| Mind Over Letter Ltd | Wholesale & retail | 2023 |
| Minderellas Events Ltd | Extraterritorial | 2026 |
| Mindly App Limited | Information & communication | 2025 |
| Mindsync Consulting Ltd | Professional & scientific | 2025 |
| Minima Yacht Club Limited | Arts & recreation | 2011 |
| Mining Frontier Recruitment Ltd | Administrative & support | 2025 |
| Minnesota Energy Limited | Energy | 2020 |
| Minr Consultancy Ltd | Real estate | 2020 |
| Mint Consultants Limited | Administrative & support | 2019 |
| Mint Contractors Limited | Administrative & support | 2016 |
| Mint Corporation Ltd | Administrative & support | 2018 |
| Mint Hygiene Ltd | Water & waste | 2013 |
| Mint Personnel Limited | Administrative & support | 2019 |
| Mint Resourcing Corporation Limited | Administrative & support | 2012 |
| Mint Resourcing Limited | Professional & scientific | 2013 |
| Mint Resourcing Personnel Ltd | Administrative & support | 2016 |
| Mira Property Group Ltd | Real estate | 2024 |
| Miracle 7 Limited | Hospitality | 2024 |
| Miran International Limited | Real estate | 2015 |
| Mirandina Ltd | Hospitality | 2020 |
| Mirasol Ltd | Manufacturing | 2025 |
| Miri Group Ltd | Construction | 2026 |
| Mirror Ltd | Information & communication | 2025 |
| Misha Property Management Ltd | Real estate | 2018 |
| Misk Ltd | Health & social care | 2024 |
| Mission Forge Ltd | Information & communication | 2025 |
| Mistory Limited | Professional & scientific | 2025 |
| Mistral Consortium Limited | Real estate | 2008 |
| Mistry Logic Limited | Information & communication | 2017 |
| Mitra Powell Associates Limited | Professional & scientific | 2020 |
| Mixabit Limited | Professional & scientific | 2005 |
| Mixed UP Pictures Limited | Information & communication | 2018 |
| MJ Mansell Limited | Construction | 2004 |
| MJ Signs + Ltd | Wholesale & retail | 2024 |