| MG Nuclear Imaging Limited | Health & social care | 2025 |
| MG RGN Services Ltd | Health & social care | 2025 |
| MGA Power Solutions Ltd | Professional & scientific | 2022 |
| MH Accountancy Solutions Ltd | Professional & scientific | 2018 |
| MHS Store Ltd | Wholesale & retail | 2018 |
| Mi-Home Rentals Ltd | Real estate | 2026 |
| Miba Haulage Ltd | Transport & logistics | 2020 |
| Michael J Burgin Limited | Construction | 2005 |
| Michael Raftery Consulting Limited | Real estate | 1994 |
| Michal Media Limited | Wholesale & retail | 2026 |
| Mick Allen Safety Services Limited | Education | 2019 |
| Mick Walsh Construction Limited | Construction | 2013 |
| Micron Analytical Limited | Professional & scientific | 2005 |
| Midway Manufacturing Ltd | Manufacturing | 2016 |
| Migration Advisory Service Ltd | Professional & scientific | 2022 |
| Mihai Maria Ltd | Transport & logistics | 2025 |
| Mihai Transport Logistic Ltd | Transport & logistics | 2026 |
| Milano Pizza Scunthorpe Ltd | Hospitality | 2024 |
| Milestone Homes and Lofts Ltd | Construction | 2022 |
| MILESTONES3D Ltd | Professional & scientific | 2019 |
| Millell Properties Limited | Real estate | 2023 |
| Miller Design Limited | Information & communication | 2015 |
| Milletts Properties Ltd | Real estate | 2025 |
| Millie’S Rental Properties Ltd | Real estate | 2022 |
| Mills Site Services Ltd | Construction | 2023 |
| Mini Anna Melts for UK Ltd | Wholesale & retail | 2022 |
| Mini Senses Limited | Wholesale & retail | 2019 |
| Ministry of Detail Ltd | Professional & scientific | 2019 |
| Miracle Investments Ltd | Health & social care | 2021 |
| Misk Transport Ltd | Transport & logistics | 2021 |
| Mission Smiles Limited | Health & social care | 2022 |
| Missoni Trading Ltd | Wholesale & retail | 2017 |
| Mistletoe Kitchen Ltd | Manufacturing | 2017 |
| Mizaans of Ashby Limited | Hospitality | 2019 |
| Mizaans of Ashby Trading Ltd | Hospitality | 2022 |
| MJ Holmes Group Ltd | Administrative & support | 2019 |
| MJ Inspection Services Ltd | Professional & scientific | 2019 |
| MJD Contracting Ltd | Wholesale & retail | 2021 |
| Mjfestate Ltd | Real estate | 2023 |
| Mjglobal Ltd | Financial services | 2011 |
| MJH Sporting Ltd | Arts & recreation | 2020 |
| MJM Developments (Portrack Grange) Limited | Real estate | 2006 |
| MJS Accounts Ltd | Professional & scientific | 2010 |
| MJS Aviation Solutions Ltd | Manufacturing | 2020 |
| MJT Electrical Services Ltd | Construction | 2023 |
| MK Software Limited | Information & communication | 2020 |
| MK Zione Store Ltd | Wholesale & retail | 2023 |
| MK Zone One Ltd | Wholesale & retail | 2024 |
| MKB Transport Ltd | Transport & logistics | 2025 |
| MKM Trio Ltd | Wholesale & retail | 2019 |
| ML Educational Services Ltd | Professional & scientific | 2022 |
| ML Rodgers Consultancy Ltd | Administrative & support | 2019 |
| MM Doctor Ltd | Health & social care | 2022 |
| MNC Distribution Ltd | Transport & logistics | 2022 |
| Mnhl Investment Limited | Real estate | 2025 |
| MNT Holdings Limited | Real estate | 2020 |
| MO Phlebotomy Ltd | Health & social care | 2020 |
| Moai Limited | Real estate | 2025 |
| Mobile Home Movements Limited | Transport & logistics | 2016 |
| Mobile Movements Limited | Extraterritorial | 2016 |
| Mobility Essentials Limited | Wholesale & retail | 2018 |
| Mobonline Ltd | Wholesale & retail | 2016 |
| Modi-Floyd Ltd | Health & social care | 2013 |
| Modular Logistics Group Limited | Administrative & support | 2014 |
| Modular Movements Ltd | Transport & logistics | 2014 |
| Modular Services Yorkshire Limited | Administrative & support | 2016 |
| Mohani Ltd | Wholesale & retail | 2016 |
| Mohanur Private Limited | Health & social care | 2012 |
| Moird Limited | Health & social care | 2022 |
| MOJ Group | Real estate | 2015 |
| Molesa Transport Ltd | Transport & logistics | 2026 |
| Mollah Properties Ltd | Construction | 2023 |
| Monarch Aesthetic Limited | Wholesale & retail | 2023 |
| Monobuoy (UK) Ltd | Extraterritorial | 2015 |
| Monty's Discount Carpets Limited | Wholesale & retail | 2010 |
| Moony PAW Limited | Wholesale & retail | 2023 |
| Moor 333 Ltd | Hospitality | 2025 |
| Moor Anaesthetic Services Ltd | Health & social care | 2021 |
| Moore Facilities Management Ltd | Construction | 2009 |
| Moore People Limited | Professional & scientific | 1996 |
| Moorwalk Limited | Real estate | 1965 |
| Moorwell Miracles Holdings Limited | Financial services | 2021 |
| Moorwell Miracles Limited | Health & social care | 2014 |
| Moorwell Transport Services Limited | Real estate | 2019 |
| Moorwells Clearance Services Ltd | Administrative & support | 2018 |
| More & Three Holding Ltd | Financial services | 2025 |
| More & Three Ltd | Real estate | 2025 |
| More & Three Removals Ltd | Water & waste | 2026 |
| Morris Young Motors Limited | Wholesale & retail | 2002 |
| Morson Furniture Company Ltd | Manufacturing | 2023 |
| Mortimeruk Letting Ltd | Real estate | 2024 |
| Mortimeruk Ltd | Construction | 2020 |
| Mortz Properties Ltd | Real estate | 2023 |
| Mortz Property Maintenance Limited | Construction | 2018 |
| Mortz Property Management Limited | Real estate | 2018 |
| Mosaic Medicine Limited | Health & social care | 2024 |
| Moss Boss Ltd | Administrative & support | 2024 |
| Motaline Limited | Transport & logistics | 1992 |
| Motor Commerce Limited | Information & communication | 2011 |
| Motorclass Scunthorpe Ltd | Wholesale & retail | 2025 |