| MED Cuisine Limited | Hospitality | 1998 |
| Medbex Electrical Contractors Limited | Construction | 2005 |
| Medenico Ltd | Wholesale & retail | 2024 |
| Media Sports Europe Limited | Professional & scientific | 2017 |
| Medical Integration Solutions Limited | Information & communication | 2025 |
| Medics Worldwide Limited | Real estate | 2000 |
| Medikent Ltd | Health & social care | 2024 |
| Medipros Billing Services Ltd | Administrative & support | 2025 |
| Medischeme Health Limited | Financial services | 2009 |
| Mediscribe Solutions Ltd | Administrative & support | 2025 |
| Medora Specialist Services Ltd | Health & social care | 2025 |
| Medsec Support Limited | Administrative & support | 2024 |
| Medsurg Limited | Wholesale & retail | 2014 |
| Medusa Metalworks Ltd | Manufacturing | 2026 |
| Medway Renovations Ltd | Construction | 2026 |
| Medway Sound Ltd | Information & communication | 2020 |
| Meerkat I.T. Solutions Limited | Extraterritorial | 2010 |
| Megan Rebecca HPY Ltd | Arts & recreation | 2022 |
| Meldane Trading Ltd | Wholesale & retail | 2020 |
| Melford Investments Limited | Real estate | 2003 |
| Melford LLP | | 2003 |
| Melford Securities Limited | Administrative & support | 1985 |
| Melia's Place Ltd | Hospitality | 2017 |
| Melissa Case Coaching Ltd | Professional & scientific | 2022 |
| Melvyn Evans Illustration & Design Ltd | Arts & recreation | 2003 |
| Memgraph Ltd | Information & communication | 2016 |
| Mentrim Limited | Wholesale & retail | 1963 |
| Meorn Limited | Information & communication | 2010 |
| Mercer LEE Limited | Administrative & support | 2009 |
| Meredith GB Consultants Ltd | Professional & scientific | 2010 |
| Merewood Construction and Civil Engineering Ltd | Construction | 2020 |
| Merewood Construction Limited | Construction | 2005 |
| Merge Digital Limited | Information & communication | 2017 |
| Merron Motor Co Limited | Wholesale & retail | 2026 |
| Meryl Gilbert Ltd | Professional & scientific | 2015 |
| MET Flooring Ltd | Construction | 2015 |
| Meta Eight Ltd | Information & communication | 2020 |
| Meta Medical Ltd | Information & communication | 2021 |
| Metcalfe Wealth Management LLP | | 2018 |
| Metis Technik Engineering | | 1994 |
| Metista Limited | Financial services | 2022 |
| Metista Services Limited | Professional & scientific | 2024 |
| Metro Contracting Limited | Construction | 2010 |
| MF Residential Holdings Limited | Real estate | 2014 |
| Mfrk Limited | Transport & logistics | 2023 |
| MGD Technology Ltd | Information & communication | 2015 |
| Mgmc Investment Holdings Ltd | Financial services | 2023 |
| MGN Advisory Ltd | Professional & scientific | 2019 |
| MH Consultancy Partner Ltd | Administrative & support | 2026 |
| MH Rail Consultancy Limited | Construction | 2016 |
| MH Trimming Ltd | Wholesale & retail | 2019 |
| MHE Investments Limited | Real estate | 1983 |
| Mhpj Ltd | Hospitality | 2017 |
| MI Climate Limited | Construction | 2018 |
| MI Smart Accounting Solutions Limited | Professional & scientific | 2024 |
| Mibm Limited | Real estate | 2022 |
| Mica Technology UK Limited | Wholesale & retail | 2003 |
| Micd Limited | Real estate | 2014 |
| Michael Day Limited | Real estate | 2003 |
| Michael Lord Limited | Wholesale & retail | 2001 |
| Michael Nesbeth Limited | Wholesale & retail | 2016 |
| Michael Robert in England Limited | Wholesale & retail | 2017 |
| Mickey Ghees Ltd | Hospitality | 2026 |
| Microbira Maap-Ir Limited | Professional & scientific | 2021 |
| Midtempo Limited | Administrative & support | 2002 |
| Midvale Limited | Wholesale & retail | 2016 |
| Mike Haynes Consulting Ltd | Financial services | 2020 |
| Milan Trading Overseas LLP | | 2016 |
| Milecross Limited | Real estate | 2016 |
| Miles Private Hire Ltd | Transport & logistics | 2014 |
| Mill Hall Property Management Company Limited | Real estate | 2016 |
| Mill Lane Shoreham Management Company Limited | Real estate | 2014 |
| Mill Pond Wood (Sevenoaks) Residents Management Company Limited | Households | 1996 |
| Millennium Quay Brokers Limited | Financial services | 2012 |
| Miller & Lockyer Construction Ltd | Construction | 2020 |
| Millfield Car Storage Ltd | Transport & logistics | 2024 |
| Millie's Care Ltd | Health & social care | 2023 |
| Milton Estates (Surrey) Ltd | Real estate | 2020 |
| Milton IP Limited | Real estate | 2024 |
| Milton Limited | Real estate | 2001 |
| Milton Property Investments Limited | Real estate | 2001 |
| Mimshack Building Services Ltd | Construction | 2014 |
| Mind and Moon Ltd | Wholesale & retail | 2025 |
| Mindmatters Consultancy Ltd | Health & social care | 2023 |
| MINDS2PERFORM Limited | Health & social care | 2024 |
| Minechain Limited | Professional & scientific | 2026 |
| Minerva Invest | Financial services | 2017 |
| Minety Limited | Real estate | 1994 |
| Minety Panels Limited | Real estate | 1983 |
| Ming YUN Sports and Culture Ltd | Professional & scientific | 2023 |
| Miqst Ltd | Professional & scientific | 2026 |
| Mirabell Limited | Administrative & support | 2005 |
| Mirabile Group Limited | Wholesale & retail | 2020 |
| Miracle Organic Labs Limited | Health & social care | 2019 |
| Mirambeau Properties Ltd | Construction | 2021 |
| Miramede Limited | Households | 1991 |
| Mirox Construction Limited | Construction | 2025 |
| Mirox Development Limited | Construction | 2014 |
| MIS Envirotech Limited | Manufacturing | 2025 |
| Mise EN Place Restaurants Ltd | Hospitality | 2024 |