| MAP Investments UK Limited | Construction | 2008 |
| Maple Road West Limited | Real estate | 2021 |
| Mapletree Meadows (Mansfield) Management Company Limited | Households | 2018 |
| Marathon Media and Marketing Limited | Information & communication | 2008 |
| Marcin Sygula Limited | Transport & logistics | 2021 |
| Mardel Construct Ltd | Construction | 2024 |
| Mardin Barbershop Ltd | Other services | 2026 |
| Maria Alla Ltd. | Health & social care | 2023 |
| Marian's Logistics Limited | Transport & logistics | 2025 |
| Marina DOR Ltd | Administrative & support | 2025 |
| Marine Hatchery Consultancy Ltd. | Agriculture & fishing | 2017 |
| Mario Auto Complex Ltd | Wholesale & retail | 2025 |
| Marite Logistics Limited | Construction | 2023 |
| Mariya London Stores Limited | Wholesale & retail | 2015 |
| Mark Cockett Building Services Ltd | Construction | 2011 |
| Mark Plant Bathroom Ltd | Manufacturing | 2020 |
| Mark Power Advisory Ltd | Professional & scientific | 2025 |
| Mark Swanborough Services Ltd | Professional & scientific | 2015 |
| Mark Watchorn SEO Limited | Information & communication | 2016 |
| Mark's Carpentry, Drywall & Ceilings Limited | Construction | 2025 |
| Market Events Ltd | Hospitality | 2022 |
| Market Street Cafe Limited | Hospitality | 2025 |
| Market Warsop Merchandise Ltd | Wholesale & retail | 2025 |
| Marketing Media Group Ltd | Professional & scientific | 2018 |
| Marley Assets Ltd | Professional & scientific | 2020 |
| Marlite Developments. Ltd | Construction | 2025 |
| Marmalade Property Limited | Real estate | 2002 |
| Marsel’S Wine Ltd | Wholesale & retail | 2025 |
| Marshall Beard Limited | Construction | 2015 |
| Marshall Joinery & Property Limited | Construction | 2026 |
| Martey Food Packaging Limited | Manufacturing | 2023 |
| Martial Arts Inspired UK Ltd | Other services | 2019 |
| Martim Limited | Real estate | 2000 |
| Martin Engineering Limited | Manufacturing | 1984 |
| Martin Wright Limited | Wholesale & retail | 2002 |
| Martyn Knox Ltd | Financial services | 2020 |
| Marvellous Memories Limited | Extraterritorial | 2000 |
| Masal Kebab & Pizza Limited | Hospitality | 2023 |
| Mason Software Ltd | Information & communication | 2026 |
| Masud Optical Services Ltd | Health & social care | 2018 |
| MAT Accountants Ltd | Professional & scientific | 2026 |
| Mathobisa Enterprises Ltd | Health & social care | 2013 |
| Matt BYE Consultancy Ltd | Professional & scientific | 2025 |
| Matt Shelton Limited | Administrative & support | 2024 |
| Matthew Bennett Architecture Ltd | Professional & scientific | 2025 |
| Matthias Transportation Ltd | Transport & logistics | 2025 |
| Maun Consultancy Services Limited | Administrative & support | 2018 |
| Maun Fire Safety Limited | Public administration | 2017 |
| Maun Interiors Limited | Administrative & support | 2013 |
| Maun Valley Limited | Construction | 2019 |
| MAX Construct Ltd | Construction | 2024 |
| MAX Media Publishing Ltd | Information & communication | 2016 |
| Maya Holdings Ltd | Real estate | 2020 |
| Mayajei Store Ltd | Professional & scientific | 2023 |
| Mayfs Paint Specialist Limited | Wholesale & retail | 2020 |
| Mayo Engineering Limited | Professional & scientific | 2000 |
| MB HR Services Ltd | Administrative & support | 2023 |
| MB Mansfield Limited | Wholesale & retail | 2009 |
| MB Service Centre Mansfield Ltd | Wholesale & retail | 2009 |
| Mbaba Transport Ltd | Transport & logistics | 2020 |
| MBC (Notts) Limited | Professional & scientific | 2021 |
| MBL Builders Ltd | Construction | 2025 |
| MC Leisure Group Ltd | Health & social care | 2019 |
| MC Stroe Tans Ltd | Transport & logistics | 2020 |
| MC United Ltd | Transport & logistics | 2019 |
| Mcbain I.S. Service Solutions Ltd. | Information & communication | 2000 |
| Mccarran Limited | Professional & scientific | 2008 |
| MCD89 Limited | Construction | 2019 |
| Mcfarlane GAS Limited | Energy | 2017 |
| MCG Lottery Ltd | Wholesale & retail | 2025 |
| Mcgregors (Mansfield) Limited | Professional & scientific | 1999 |
| Mcgregors Audit Services Limited | Extraterritorial | 2006 |
| Mcgregors Business Network Limited | Financial services | 2006 |
| Mcgregors CCP Ltd | Professional & scientific | 2018 |
| MCL Energy Ltd. | Manufacturing | 1991 |
| Mclafferty Investments Limited | Financial services | 2023 |
| MCR Garage Ltd | Professional & scientific | 2025 |
| MCW Digital Consulting Limited | Professional & scientific | 2025 |
| MD Anaesthetic Solutions Limited | Health & social care | 2014 |
| MDE Contractors Ltd | Administrative & support | 2022 |
| MDK Cranes Limited | Construction | 2022 |
| MDL Strategic Advisory Ltd | Professional & scientific | 2026 |
| MDZ Trans Ltd | Administrative & support | 2016 |
| ME Environmental Limited | Water & waste | 2019 |
| ME Gusta Clinic Ltd | Other services | 2023 |
| ME Holdings (Mansfield) Limited | Real estate | 2022 |
| Meadow Nails Ltd | Other services | 2018 |
| Mechanician Limited | Wholesale & retail | 1992 |
| Medboom Empire Ltd | Transport & logistics | 2026 |
| Meden Employment Solutions Limited | Administrative & support | 2016 |
| Meden Mouldings Solutions Ltd | Manufacturing | 2025 |
| Medi-Cell Rentals Limited | Professional & scientific | 2007 |
| Medicard Limited | Extraterritorial | 1993 |
| Medicor Ltd | Administrative & support | 2025 |
| Medley Precision Engineers Ltd | Administrative & support | 2000 |
| Meduoye UK Ltd | Health & social care | 2021 |
| MEE Development Limited | Information & communication | 2020 |
| MEE Holdings Ltd | Extraterritorial | 2013 |
| Mee@Home Healthcare Limited | Administrative & support | 2022 |
| Mega Chickens Ltd | Manufacturing | 2007 |