| MLU Properties Limited | Real estate | 2020 |
| MM Refrigeration Limited | Administrative & support | 2002 |
| MMC Hardmetal UK Limited | Wholesale & retail | 1967 |
| MMH43 Ltd | Administrative & support | 2017 |
| Mmts West Midlands Ltd | Wholesale & retail | 2023 |
| MNC Design Services Ltd | Professional & scientific | 2011 |
| Mobi Shack Ltd | Wholesale & retail | 2014 |
| Mode Scaffolding Ltd | Construction | 2023 |
| Moden Properties Ltd | Real estate | 2024 |
| Modern Fabs Ltd | Manufacturing | 2020 |
| Modern Home Improvements Ltd | Construction | 2023 |
| Modern Patio & Driveways Ltd | Administrative & support | 2021 |
| Modjoe Ltd | Real estate | 2018 |
| Mojo Group Holdings Ltd | Real estate | 2025 |
| Mojo Lettings Limited | Real estate | 2017 |
| Momay Ltd | Information & communication | 2023 |
| Monarch GAS Limited | Wholesale & retail | 2013 |
| Monecono Limited | Extraterritorial | 2025 |
| Money Matters Advice Services Limited | Professional & scientific | 2025 |
| Monnat Construction Ltd | Construction | 2023 |
| Mono Environmental Ltd | Professional & scientific | 2021 |
| Montana Events Ltd | Arts & recreation | 2002 |
| Monty's (Midlands) Ltd | Wholesale & retail | 2025 |
| Moo&Bro Events Ltd | Hospitality | 2022 |
| Mood Creative Ltd | Wholesale & retail | 2025 |
| Mood Solutions Ltd | Construction | 2024 |
| Moorcroft Consultants Holdings Limited | Financial services | 2023 |
| Moorcroft Consultants Limited | Professional & scientific | 2018 |
| Mopane Limited | Professional & scientific | 2014 |
| Moreno Consult & Construct (UK) Ltd | Real estate | 2022 |
| Morfc Ltd | Hospitality | 2025 |
| Morgan Louw Limited | Administrative & support | 2025 |
| Morindin Ltd | Households | 2024 |
| Mormet (Aluminium) Limited | Water & waste | 1997 |
| Morris Manors Limited | Real estate | 2019 |
| Morris Property Maintenance Limited | Construction | 2021 |
| Morsano Business Projects Ltd | Information & communication | 2024 |
| Mortgages by Heather Wall Ltd | Financial services | 2017 |
| Morton Squared Development Limited | Construction | 2024 |
| Most Impressive Limited | Professional & scientific | 2023 |
| Mother Lode PR Limited | Professional & scientific | 2017 |
| Mother Nature Retail Ltd | Wholesale & retail | 2023 |
| MOTIV8ED Ltd | Wholesale & retail | 2026 |
| Motor Contracts Limited | Wholesale & retail | 1963 |
| Motor Vehicle Services (Tamworth) Limited | Wholesale & retail | 2011 |
| Mountrek Outdoors Ltd | Wholesale & retail | 2026 |
| Move for Wellness 21 Ltd | Health & social care | 2020 |
| Move PT Limited | Other services | 2024 |
| Move With Marisa Ltd | Health & social care | 2023 |
| Movesmart Mortgage Solutions Ltd | Financial services | 2021 |
| Movewise Logistics Ltd | Transport & logistics | 2025 |
| MOW ‘N’ SOW Gardening Services Ltd | Administrative & support | 2026 |
| MOY Networx Limited | Professional & scientific | 2024 |
| Mo’S Direct Ltd | Wholesale & retail | 2026 |
| MP Property Developers Ltd | Real estate | 2023 |
| MP1 Logistics Ltd | Transport & logistics | 2023 |
| Mpda Ltd | Information & communication | 2016 |
| MPE Consultants Ltd | Professional & scientific | 2023 |
| MR Flexihire Limited | Administrative & support | 2018 |
| MR Plumb Ltd | Construction | 2015 |
| Mr-Merch Ltd. | Wholesale & retail | 2014 |
| MRB Middleton Ltd | Wholesale & retail | 2024 |
| MRG Transport Ltd | Transport & logistics | 2021 |
| Mrg.Midlands Limited | Administrative & support | 2023 |
| MRO Lettings Limited | Real estate | 2019 |
| MRV Interiors Ltd | Construction | 2009 |
| MSB Global Services Ltd | Arts & recreation | 2023 |
| MSC Investments Ltd | Real estate | 2017 |
| MSC Property Holdings Limited | Real estate | 2026 |
| Msigma Ltd | Education | 2013 |
| MSP Building Contractors Ltd | Construction | 2021 |
| MT Services Computer Systems Limited | Information & communication | 1998 |
| Mtaf Ltd | Wholesale & retail | 2019 |
| MTC Engineering and Engraving Services Limited | Professional & scientific | 2010 |
| Mtec Freight Services Limited | Transport & logistics | 2003 |
| MTR Logistics Ltd | Transport & logistics | 2018 |
| MTS Landscaping & Groundworks Ltd | Administrative & support | 2025 |
| Muehga Limited | Wholesale & retail | 2022 |
| Mughal Sultan Limited | Hospitality | 2019 |
| Mugs by ALY Ltd | Manufacturing | 2025 |
| Muliebrity Airedale Terriers Limited | Agriculture & fishing | 2019 |
| Murlac Ltd | Administrative & support | 2010 |
| Murray's Monumental Masons Limited | Other services | 2023 |
| Murray’S Property Lettings Ltd | Real estate | 2023 |
| Muse London Limited | Manufacturing | 2026 |
| Music Industry Consultancy Limited | Professional & scientific | 2021 |
| MVP Auto Ltd | Transport & logistics | 2018 |
| MW Building Renovations Ltd | Construction | 2025 |
| MW Ceilings Limited | Construction | 2017 |
| MW Residential (Tamworth) Limited | Real estate | 2015 |
| MW Shed Bases Limited | Construction | 2021 |
| MW Surgical Consultancy Ltd | Health & social care | 2025 |
| MWP Electrical Ltd | Construction | 2022 |
| My G Barber Shop Ltd | Other services | 2023 |
| My Iglu Limited | Real estate | 2017 |
| My Skin Health Clinic Ltd | Other services | 2023 |
| Myek Ltd | Health & social care | 2019 |
| Myfreight Ltd | Transport & logistics | 2018 |
| Myhomecover Ltd | Other services | 2025 |
| N & D Morley Holdings Ltd | Financial services | 2026 |