| MI MI Nails and Beauty Ltd | Other services | 2023 |
| Mi.Cider Life Limited | Education | 2015 |
| Mi.Life Limited | Health & social care | 2012 |
| MIA Auto Drive Motors Ltd | Wholesale & retail | 2025 |
| MIA Nails & Spa Ltd | Other services | 2022 |
| Miahh Ltd | Real estate | 2025 |
| Miami Sun (Loughborough) Limited | Other services | 2018 |
| MIB Tiling Ltd | Construction | 2024 |
| MIC Financial Ltd | Administrative & support | 2018 |
| Michael Reed Wealth Management Limited | Financial services | 2015 |
| Michael Services Garage Ltd | Wholesale & retail | 2022 |
| Micon Mission Limited | Wholesale & retail | 2024 |
| Micropropagation Services (E.M.) Limited | Agriculture & fishing | 1985 |
| Midco P&P Holdings Limited | Financial services | 2015 |
| Midco Print and Packaging Holdings Limited | Financial services | 2024 |
| Midland Asset Services Ltd | Financial services | 2019 |
| Midland Automotive Limited | Wholesale & retail | 2026 |
| Midland Fire Direct Ltd | Other services | 2016 |
| Midland Guardians Football Club Ltd | Manufacturing | 2024 |
| Midland Letting Services Limited | Real estate | 2020 |
| Midland Management Services Limited | Construction | 2005 |
| Midland Metals Recycling Limited | Water & waste | 2005 |
| Midland Properties (Loughborough) Limited | Real estate | 1946 |
| Midlands Locksmiths Ltd | Administrative & support | 2023 |
| Midlands Management Services Ltd | Professional & scientific | 2025 |
| Midlands Power Limited | Construction | 2022 |
| Midlands Premier Roofline (Windows) Limited | Construction | 2019 |
| Midlands Premier Roofline Marketing Limited | Construction | 2018 |
| Midlands Simple Cremations Limited | Other services | 2025 |
| Midm ENT Ltd | Wholesale & retail | 2018 |
| Midshires Catering Equipment Limited | Manufacturing | 2010 |
| Mighty PEN Capital Ltd | Households | 2025 |
| Mila EFE Ltd | Hospitality | 2023 |
| Milan Ristic Ltd | Transport & logistics | 2019 |
| Military Precision Safety Ltd | Professional & scientific | 2025 |
| Milk Property Holdings Limited | Real estate | 2025 |
| Mill Fields (Broughton Astley) Management Company Limited | Real estate | 2017 |
| Millen Developments Limited | Financial services | 2023 |
| Millennium Pubs Ltd | Hospitality | 2018 |
| Miller Plumbing and Heating Services Ltd | Construction | 2022 |
| Millie's Warehouse Ltd | Wholesale & retail | 2024 |
| Millivolt Electrical Services Limited | Manufacturing | 2016 |
| Milloc Properties Ltd | Real estate | 2025 |
| Minarchi Ltd | Other services | 2024 |
| Mind AID UK. CIC | Health & social care | 2023 |
| Mind Over Matter Promotions Ltd | Professional & scientific | 2025 |
| Mind SET Match Ltd | Professional & scientific | 2017 |
| Mindofram Ltd | Information & communication | 2024 |
| Minerest Motors Limited | Wholesale & retail | 1977 |
| Mini JOB Maintenance Ltd | Construction | 2018 |
| Mini Market & Vape Store Limited | Wholesale & retail | 2025 |
| Mini Market Hub Ltd | Wholesale & retail | 2025 |
| Mini Pancakes UK Ltd | Wholesale & retail | 2022 |
| Minibrickchic CIC | Education | 2026 |
| Miniraffle Limited | Arts & recreation | 2023 |
| Minithingsforlife Ltd | Wholesale & retail | 2012 |
| Mint Bay Media Ltd | Information & communication | 2023 |
| Mirage Elmo Global Limited | Administrative & support | 2024 |
| Mirka Enterprises Limited | Financial services | 2025 |
| Miruna Trans Ltd | Transport & logistics | 2015 |
| Mishu the D Ltd | Transport & logistics | 2018 |
| Misterton Bistro Limited | Hospitality | 2020 |
| Misterton Chippy Limited | Hospitality | 2019 |
| Mitchcroft Limited | Extraterritorial | 2000 |
| Mitchell Project Services Limited | Professional & scientific | 1998 |
| Mitech Scout Ltd | Information & communication | 2018 |
| Miths Properties Limited | Households | 2021 |
| MJ Hutchinson Developments Ltd | Construction | 2018 |
| MJ Retailers Ltd | Wholesale & retail | 2022 |
| MJC Financial Ltd | Extraterritorial | 2016 |
| MJH Auto Solutions Limited | Wholesale & retail | 2025 |
| MJL Direct Limited | Wholesale & retail | 2025 |
| MJS Precision Machining Ltd | Manufacturing | 2023 |
| MJW Electrical Services (Nottingham) Limited | Construction | 2013 |
| MK 65 Services Limited | Health & social care | 2015 |
| MK Roadshow FX Ltd | Administrative & support | 2023 |
| MKH Rail Ltd | Professional & scientific | 2024 |
| Mkizlocums Ltd | Health & social care | 2019 |
| MKN Homes Ltd | Real estate | 2025 |
| ML Swimming Limited | Arts & recreation | 2017 |
| MLM Services (UK) Limited | Information & communication | 2011 |
| Mlynski Design Ltd | Professional & scientific | 2008 |
| MM Beauty Group Ltd | Wholesale & retail | 2021 |
| MM Media Partners Limited | Administrative & support | 2021 |
| MM Tech Ltd | Information & communication | 2025 |
| Mnkyfce Property Ltd | Households | 2024 |
| MNU Holdings Ltd | Financial services | 2018 |
| MNU Limited | Health & social care | 2016 |
| Mobilestop Ltd | Manufacturing | 2026 |
| Mobility Centre Midlands Limited | Wholesale & retail | 2015 |
| Modality Group Limited | Manufacturing | 2013 |
| Modella Studio Ltd | Professional & scientific | 2026 |
| Modern Painters, New Decorators Ltd | Wholesale & retail | 2019 |
| Modern Retail Services Limited | Construction | 2024 |
| Modestus Limited | Real estate | 2015 |
| Modular Growth Ltd | Manufacturing | 2019 |
| Moel Tryfan Rolling Stock Co Ltd | Extraterritorial | 2018 |
| MOG Marketing Ltd | Professional & scientific | 2024 |
| Moja-Bites Limited | Hospitality | 2025 |
| Moja-Nites Ltd | Hospitality | 2025 |