| Mela Supported Living Limited | Health & social care | 2025 |
| Mela’S Kitchen Ltd | Wholesale & retail | 2020 |
| Melitta UK Ltd. | Manufacturing | 1976 |
| Mellza Ltd | Administrative & support | 2020 |
| Melmarkton Limited | Health & social care | 2013 |
| Melnais Ltd | Transport & logistics | 2019 |
| Melody Merchants Ltd | Wholesale & retail | 2024 |
| Mendiola Ltd | Other services | 2019 |
| Mendis Cleaning Service Ltd | Administrative & support | 2025 |
| Mendis Vision Estates Ltd | Real estate | 2025 |
| Mennell & Company Limited | Real estate | 2025 |
| Mentiscurapraxis Ltd | Health & social care | 2026 |
| MEP Partnership Ltd | Construction | 2013 |
| Mercian Consulting Ltd | Construction | 2021 |
| Mercury Margin Limited | Professional & scientific | 2019 |
| Meretown Consultancy Ltd | Professional & scientific | 2025 |
| Meridian Sales Limited | Administrative & support | 2021 |
| Merrythought Property Limited | Financial services | 2016 |
| Merrythought Village Limited | Real estate | 2016 |
| Mesh Stock Ltd | Wholesale & retail | 2005 |
| Messiter Project Cleaning Services Limited | Administrative & support | 2024 |
| Meta Contracting & Building Company Limited | Administrative & support | 2020 |
| Meta-Expo Limited | Construction | 2025 |
| Metability Limited | Professional & scientific | 2025 |
| Metal LAB Technologies Ltd | Information & communication | 2023 |
| Metashift Limited | Professional & scientific | 2009 |
| Metro Home Limited | Construction | 2003 |
| Metromoh Healthcare Ltd | Extraterritorial | 2025 |
| Metses Ltd | Wholesale & retail | 2019 |
| Mezeco Medical Practice Limited | Health & social care | 2024 |
| MFR Logistics Ltd | Transport & logistics | 2025 |
| MFS Garage Ltd | Wholesale & retail | 2022 |
| MGA & NDA Holdings Limited | Real estate | 2012 |
| MGM Care Services Ltd | Health & social care | 2011 |
| MGS Signs Ltd | Manufacturing | 2016 |
| MHH Real Estates Limited | Real estate | 2026 |
| MHP Homes and Property Ltd | Real estate | 2024 |
| Miad Healthcare Limited | Education | 2003 |
| MIC Burns Limited | Information & communication | 2020 |
| Mich Limited | Health & social care | 2018 |
| Michael Paul Consultancy Limited | Professional & scientific | 2020 |
| Michdeg and Co Limited | Transport & logistics | 2019 |
| Michelle Bunyan Ltd | Health & social care | 2023 |
| Mick the Handyman Limited | Administrative & support | 2014 |
| MICKEYMAKES3D Ltd | Arts & recreation | 2026 |
| Micron Engineering Services Limited | Professional & scientific | 2016 |
| Micronz Limited | Wholesale & retail | 2010 |
| Mida Taylor Limited | Real estate | 2013 |
| Middas Interior Solutions Ltd | Administrative & support | 2013 |
| Middleham Solutions Ltd | Transport & logistics | 2023 |
| Midland Alloy Holdings Limited | Professional & scientific | 2006 |
| Midland Alloy Limited | Manufacturing | 1992 |
| Midland Computers Holdings Ltd | Financial services | 2024 |
| Midland Computers Ltd. | Information & communication | 1999 |
| Midland Fencing Limited | Construction | 2020 |
| Midland Financial Advisers Limited | Financial services | 2003 |
| Midland Inns Ltd | Hospitality | 2014 |
| Midland Optical LAB Limited | Manufacturing | 2011 |
| Midlands Physiotherapy and Wellness Ltd | Health & social care | 2023 |
| Midlands Pitch Marking Ltd | Administrative & support | 2025 |
| Midshire Surveyors Ltd | Professional & scientific | 2026 |
| Midway Tools Limited | Wholesale & retail | 1975 |
| Mighty Oaks Academy Trust Ltd | Education | 2011 |
| Mika Recruitment Ltd | Administrative & support | 2025 |
| Mikeload Ltd | Other services | 2018 |
| Mikeyb TCG Ltd | Wholesale & retail | 2025 |
| Mikrops Ltd | Other services | 2018 |
| Milden Properties Limited | Real estate | 1994 |
| Mildene Nursery Limited | Extraterritorial | 2011 |
| Milestone-Uk Limited | Wholesale & retail | 2024 |
| Miletin Ltd | Other services | 2019 |
| Millbank Store Limited | Wholesale & retail | 2024 |
| Millbay Marina Ltd | Real estate | 2023 |
| Millionairemarket Ltd | Wholesale & retail | 2023 |
| Milonic Ltd | Administrative & support | 2002 |
| Milsami Ltd | Other services | 2020 |
| Miltech Controls Limited | Administrative & support | 2018 |
| MIM Recruitment Limited | Administrative & support | 2022 |
| Mina Nails Telford Ltd | Other services | 2025 |
| Minafon Services Ltd | Professional & scientific | 2006 |
| Minareese Ltd | Health & social care | 2022 |
| Mind Over Matter Movement CIC | Wholesale & retail | 2024 |
| Mind the Emotion Ltd | Education | 2023 |
| Mindflix Media Ltd | Public administration | 2022 |
| Mindful Coaching Today Ltd | Professional & scientific | 2020 |
| Mindset Property Ltd | Households | 2019 |
| Mindset Soldier Coaching Ltd | Wholesale & retail | 2025 |
| Minexa Limited | Mining & quarrying | 2024 |
| Mings House Limited | Hospitality | 2003 |
| Mini Ballers Academy Ltd | Education | 2025 |
| Mini Minds Matter Most Ltd | Health & social care | 2025 |
| Mini Musicians Ltd | Education | 2023 |
| Minilam Ltd | Other services | 2019 |
| Minoan Taste Ltd | Wholesale & retail | 2016 |
| Minootravel Media Production & Services Ltd | Information & communication | 2022 |
| Minor Formula Ltd | Manufacturing | 2017 |
| Minute Money Limited | Financial services | 2026 |
| Miro Global Services Ltd | Manufacturing | 2022 |
| Mirza Investments U.K. Ltd | Real estate | 2024 |
| Misanya Ltd | Transport & logistics | 2025 |