| Luke Freeman Holdings Ltd | Professional & scientific | 2021 |
| Luminex Energy Limited | Construction | 2024 |
| Lumnuss Ltd | Administrative & support | 2024 |
| Lunix Property Ltd | Real estate | 2025 |
| LWT Services Ltd | Transport & logistics | 2015 |
| LXH Ltd | Other services | 2024 |
| Lymer's Assist Ltd | Transport & logistics | 2014 |
| Lymer's Group Ltd | Financial services | 2022 |
| Lymer's Property Rentals Limited | Real estate | 2021 |
| M and H Supplies and Services Ltd | Manufacturing | 2025 |
| M C Textile Consultants Ltd | Professional & scientific | 2021 |
| M Whitaker Joinery & Building Services Limited | Manufacturing | 2010 |
| M&J Comms Limited | Information & communication | 2021 |
| M&R Controls (UK) Limited | Manufacturing | 2005 |
| Mack Air Ltd | Manufacturing | 2021 |
| MAL Property & Utilities Limited | Construction | 2023 |
| Maltby Forman Limited | Administrative & support | 2017 |
| MAN and Van for Hire Sutton in Ashfield Ltd | Transport & logistics | 2025 |
| Mancave Collectables Limited | Wholesale & retail | 2015 |
| Mango Pictures Ltd | Professional & scientific | 2025 |
| Manjaly's Enterprises Ltd | Administrative & support | 2021 |
| Manny’S Store Limited | Wholesale & retail | 2025 |
| Mansfield Memorials Ltd | Administrative & support | 2003 |
| Mansfield Pallets Ltd | Manufacturing | 2022 |
| Mansfield Retail Ltd | Wholesale & retail | 2025 |
| Mansfield Self Storage Ltd | Transport & logistics | 2023 |
| Mapleston Leisure Ltd | Arts & recreation | 2026 |
| Mapleston Properties and Developments Ltd | Real estate | 2021 |
| Marali Haulage Limited | Transport & logistics | 2018 |
| Margaret Mcqueen Models Ltd | Professional & scientific | 2025 |
| Mario Pizza Express Ltd | Hospitality | 2026 |
| Mariostefantransport Ltd | Transport & logistics | 2026 |
| Mark a Cross Contracting UK Ltd | Construction | 2020 |
| Mark Watkins Holdings Limited | Financial services | 2022 |
| Marra Painting & Decorating Ltd | Construction | 2022 |
| Marvellous 3D Prints Ltd | Manufacturing | 2026 |
| MAS Convenience Store Ltd | Wholesale & retail | 2020 |
| Mason & Sons Plumbing & Heating Ltd | Construction | 2018 |
| Mastershield Roofing Ltd | Construction | 2026 |
| Matchsync Ltd | Information & communication | 2025 |
| MATCHWORK5 Limited | Professional & scientific | 2009 |
| Matchworks Property Management Ltd | Households | 2023 |
| Maun Valley Installations Limited | Construction | 2025 |
| Maun Valley Motor Group Limited | Wholesale & retail | 2026 |
| Maun Valley Products Limited | Wholesale & retail | 2025 |
| MAX Realty Ltd | Real estate | 2022 |
| Maxkleen Limited | Wholesale & retail | 2019 |
| Maya Creations Ltd | Wholesale & retail | 2025 |
| Maya Minimarket Ltd | Wholesale & retail | 2022 |
| Mazark Consults Limited | Real estate | 2014 |
| MD Online Interiors Ltd | Professional & scientific | 2024 |
| MDD Haulage Ltd | Transport & logistics | 2026 |
| MDK Exterior Cleaning Services Limited | Administrative & support | 2022 |
| Meade's on the Move Ltd | Transport & logistics | 2025 |
| Mebropeaccess Ltd | Construction | 2019 |
| Meleknarin Limited | Hospitality | 2024 |
| Melform Limited | Manufacturing | 2015 |
| Meridian Lightweight Technologies UK Limited | Manufacturing | 2008 |
| Metalogalva Limited | Manufacturing | 2015 |
| Metamorphic Empowerment Ltd | Other services | 2024 |
| Mezz Independent Trading Ltd | Wholesale & retail | 2026 |
| Midland Home Repairs Ltd | Construction | 2017 |
| Midlands Support Ltd | Health & social care | 2018 |
| MIHAI77 Transport Ltd | Transport & logistics | 2026 |
| Mill Lining Services Limited | Professional & scientific | 2025 |
| Milldale 1964 Limited | Extraterritorial | 2014 |
| Milldaw Equestrian Ltd | Agriculture & fishing | 2026 |
| Miller Knight Estates Ltd | Real estate | 2016 |
| Mindful Sprouts CIC | Education | 2023 |
| Minerva Trading Ltd | Wholesale & retail | 2016 |
| Minster Optical Limited | Wholesale & retail | 2012 |
| Mission Components Limited | Other services | 2006 |
| Mission Corporation (UK) Limited | Wholesale & retail | 2000 |
| Mitchell Diesel Limited | Manufacturing | 1974 |
| Mitchell's (of Mansfield) Limited | Transport & logistics | 2004 |
| MJC Web Solutions Ltd | Information & communication | 2015 |
| MKN Software Solutions Limited | Information & communication | 2019 |
| Mkzs Investments Limited | Wholesale & retail | 2018 |
| MM MAC Ltd | Construction | 2023 |
| MM Speed Ltd | Transport & logistics | 2020 |
| MNS Holding Estate Limited | Real estate | 2026 |
| MNT Limited | Administrative & support | 2005 |
| MOF Software Consulting Limited | Information & communication | 2012 |
| Molly Hopkins Limited | Professional & scientific | 2021 |
| Monkeybox Ltd | Wholesale & retail | 2020 |
| Moonlight Sutton Ltd | Hospitality | 2025 |
| Moreissh Ltd | Wholesale & retail | 2019 |
| Moreworth Care Limited | Health & social care | 2025 |
| Morley and Co Lettings Ltd | Real estate | 2025 |
| Move Memo Ltd | Real estate | 2025 |
| MPF Properties Limited | Real estate | 2020 |
| MR Blue Vape Ltd | Wholesale & retail | 2026 |
| MR Wheelie Wash Limited | Water & waste | 2012 |
| MSB Site Services Ltd | Construction | 2026 |
| MSL Kitchens Bathrooms and Bedrooms Limited | Construction | 2025 |
| MTM Construction Services Ltd | Construction | 2019 |
| Muddled Minds CIC | Education | 2023 |
| Mulberry Business Services Limited | Administrative & support | 2018 |
| Munchies LW Ltd | Hospitality | 2023 |
| My Healing Flows Limited | Extraterritorial | 2024 |