| Millhouse Power Limited | Professional & scientific | 2015 |
| Millineryhut Limited | Wholesale & retail | 2020 |
| Milltown Embroidery Ltd | Manufacturing | 2019 |
| Mimo Construction Limited | Construction | 2020 |
| Mimo Consultants Ltd | Professional & scientific | 2016 |
| Mimo Developments Limited | Professional & scientific | 2015 |
| MIN Gems Limited | Manufacturing | 2014 |
| Mind 1ST Limited | Wholesale & retail | 2006 |
| Mind Right Limited | Health & social care | 2020 |
| Mindcet Limited | Education | 2021 |
| Mindcet Productions Limited | Information & communication | 2020 |
| Mindcheck One Two C.I.C. | Other services | 2018 |
| Mindful Marketing Ltd | Information & communication | 2017 |
| Mini Movers Warrington Limited | Transport & logistics | 2022 |
| Mini Shred Ltd | Water & waste | 2019 |
| Minster (NW) Ltd | Manufacturing | 2021 |
| Minsterwest Ltd | Other services | 2012 |
| Mint Looks Fashion Ltd | Wholesale & retail | 2023 |
| Mint Motorsport Limited | Arts & recreation | 2023 |
| Mint Property Partners Ltd | Real estate | 2025 |
| Minty Investments Ltd | Real estate | 2024 |
| Minty Marketing Limited | Financial services | 2023 |
| Miradex Consulting Limited | Professional & scientific | 2025 |
| Miriam Private Limited | Health & social care | 2019 |
| Mirider Limited | Manufacturing | 2019 |
| Mischa Baker Creator Limited | Information & communication | 2025 |
| Mission Care Consultancy Ltd | Health & social care | 2025 |
| Mission Nutrition Limited | Hospitality | 2015 |
| Mission SS Holdings Limited | Financial services | 2024 |
| Mitad Limited | Wholesale & retail | 2022 |
| Mitone Limited | Extraterritorial | 1988 |
| Mitra - ROY Properties Limited | Real estate | 2018 |
| Mitre Civils UK Ltd | Construction | 2022 |
| MIX Shawarma Ltd | Hospitality | 2025 |
| MJ Boxing & Fitness Ltd | Arts & recreation | 2022 |
| MJ Sales Support Ltd | Administrative & support | 2015 |
| MJB GAS Plumbing & Rayburn Ltd | Construction | 2009 |
| MJG Electrical Installations Ltd | Construction | 2026 |
| MJH Consulting Solutions Ltd | Information & communication | 2007 |
| MJH Systems Ltd | Information & communication | 1992 |
| MJK (Investments) Ltd | Professional & scientific | 2000 |
| MJK Design & Build Limited | Construction | 2020 |
| MJL Installs Ltd | Other services | 2023 |
| MJS Contractors (NW) Ltd | Construction | 2014 |
| MK Whyte Holdings Limited | Real estate | 2019 |
| MK2 Property Ltd | Real estate | 2026 |
| MKA Scaffolding Ltd | Construction | 2015 |
| MLC Logistics Limited | Construction | 2020 |
| MLG Facades & Construction Ltd | Construction | 2019 |
| MM Fencing and Arenas Ltd | Construction | 2010 |
| MML Financial Associates Ltd | Financial services | 2008 |
| Mmlds Limited | Transport & logistics | 2016 |
| Mmso Consulting Ltd | Professional & scientific | 2023 |
| MNE Consulting Ltd | Other services | 2022 |
| MNM Cars Ltd | Wholesale & retail | 2020 |
| MNS Residential Ltd | Real estate | 2021 |
| Mo's News Limited | Wholesale & retail | 2014 |
| Moaaz and Co Limited | Wholesale & retail | 2021 |
| Mobile Home and Holiday Estates(U.K)Limited | Manufacturing | 1974 |
| Mobile Measurement Services Limited | Professional & scientific | 2003 |
| Mobile-E-Solutions Limited | Information & communication | 2008 |
| Modden Group Limited | Wholesale & retail | 2020 |
| Model Based Solutions Ltd | Manufacturing | 2024 |
| Modern Matrix Ltd | Wholesale & retail | 2021 |
| Moderna Developments Ltd | Real estate | 2019 |
| Moderna Kitchen and Bedroom Ltd | Construction | 2019 |
| Modos Property Services Limited | Administrative & support | 2009 |
| Modular Housing (UK) Ltd | Construction | 2025 |
| Mogbog UK Ltd | Wholesale & retail | 2022 |
| Mojos Marketing Services Ltd | Professional & scientific | 2024 |
| Mollie Elise Aesthetic's Ltd | Health & social care | 2021 |
| Mollington Contracts Ltd | Construction | 2006 |
| Molmay Limited | Manufacturing | 2017 |
| Molteig Ltd | Manufacturing | 2014 |
| Momentum Contemporary Championships Ltd | Education | 2022 |
| Monarch Roofing Northwest Ltd | Construction | 2022 |
| Monarch Trading Limited | Extraterritorial | 2002 |
| Moncrieff Property Services Ltd | Real estate | 2017 |
| Mondo Cloud Ltd | Information & communication | 2024 |
| Money Managers (UK) Ltd | Financial services | 2013 |
| Moneytreeineuxton Limited | Hospitality | 2025 |
| Monks Marketing & Media Ltd | Professional & scientific | 2017 |
| Montessori Trove Limited | Wholesale & retail | 2023 |
| Montrose Conveyancing Ltd | Professional & scientific | 2019 |
| Moonfleet Property LLP | | 2015 |
| Moor Park Freehold Limited | Real estate | 2024 |
| Moorax Capital Ltd | Financial services | 2025 |
| Moorax Property Ltd | Extraterritorial | 2024 |
| Moore's Plumbing & Heating Limited | Construction | 2021 |
| Moorhen Drainage Limited | Construction | 2021 |
| Moovilla Ltd | Real estate | 2021 |
| More Living Space Limited | Construction | 2015 |
| More Milk (NW) Ltd | Wholesale & retail | 2025 |
| More Than Mummies Ltd | Information & communication | 2011 |
| Morg-Haul (European) Ltd | Transport & logistics | 2019 |
| Morgan Bros (Metalwork Designs) Limited | Professional & scientific | 2012 |
| Morgenfrisk Limited | Wholesale & retail | 2018 |
| Moriarty Talent Management Limited | Administrative & support | 2024 |
| Morini Property Ltd | Real estate | 2017 |
| Morish Snacks Limited | Administrative & support | 2024 |