| M.A. Lodge (Shopfitters) Limited | Construction | 2003 |
| M.A.A.H Estates Ltd | Construction | 2025 |
| M.A.M. Auto Ltd | Manufacturing | 2025 |
| M.A.M. European & African Foods Ltd | Wholesale & retail | 2020 |
| M.A.P Developments (N.E) Limited | Manufacturing | 2011 |
| M.Ahmed Consultancy Ltd | Financial services | 2017 |
| M.B. Air Limited | Transport & logistics | 1985 |
| M.B. European Limited | Transport & logistics | 1990 |
| M.B. Precision Engineering (North East) Limited | Manufacturing | 2005 |
| M.Bilal.Ukltd Ltd | Wholesale & retail | 2025 |
| M.D. Advisory Services Ltd | Professional & scientific | 2018 |
| M.F. Foods (N.E.) Limited | Wholesale & retail | 2019 |
| M.G.I.S.D. Limited | Construction | 1999 |
| M.K Roofing Construction Ltd | Construction | 2024 |
| M.K Systems NE Ltd | Construction | 2026 |
| M.L.A Haulage Ltd | Transport & logistics | 2016 |
| M.M Plumbing & Heating Engineer Limited | Construction | 2018 |
| M.M.R Motor Group Limited | Wholesale & retail | 2018 |
| M.M.S Handy-Works Ltd | Construction | 2018 |
| M.S. & S. Shahid Limited | Professional & scientific | 2004 |
| M2 and M Ltd | Health & social care | 2016 |
| M2 Electrical Contractors Limited | Construction | 2005 |
| M2B Ltd | Construction | 2026 |
| M2T Limited | Hospitality | 2019 |
| M3 Bigg Market Ltd | Hospitality | 2022 |
| M3S Consultancy Ltd | Information & communication | 2025 |
| M4SCORE Limited | Real estate | 2024 |
| M@N Construction Limited | Construction | 2015 |
| MA & P Consulting Ltd | Professional & scientific | 2023 |
| MA & Sun UK Ltd | Information & communication | 2022 |
| MA Brothers (Retail) Limited | Wholesale & retail | 2012 |
| MA Brothers (Wholesale) Limited | Wholesale & retail | 2012 |
| MA Meats Ltd | Wholesale & retail | 2025 |
| MA Prestige Living Ltd. | Hospitality | 2025 |
| MA Property Newcastle Ltd | Real estate | 2025 |
| MA Survey Engineering Services Limited | Construction | 2018 |
| Ma-Esp Ltd | Financial services | 2020 |
| MA3 Homes Ltd | Real estate | 2025 |
| MA3 Limited | Wholesale & retail | 2020 |
| MA3 Music Ltd | Information & communication | 2025 |
| Maarwa Limited | Wholesale & retail | 2021 |
| Maas Holdings Limited | Financial services | 2020 |
| MAB Machine Services Ltd | Professional & scientific | 2018 |
| MAB Systems Limited | Information & communication | 2016 |
| Maba Transport Ltd | Transport & logistics | 2025 |
| Mabilla International Limited | Professional & scientific | 2016 |
| Mableson Hall Limited | Professional & scientific | 2018 |
| Mabtacenterprises Ltd | Information & communication | 2019 |
| Mabu (Holdings) Limited | Other services | 2020 |
| MAC and Phone Repair Newcastle Ltd | Extraterritorial | 2022 |
| MAC Deli (Newcastle) Ltd | Wholesale & retail | 2019 |
| MAC Developments (North East) Ltd | Other services | 2017 |
| MAC NE Limited | Financial services | 2025 |
| MAC NE Recruitment Limited | Professional & scientific | 2020 |
| MAC Projects International Ltd | Administrative & support | 2012 |
| MAC Repair Jesmond Ltd | Information & communication | 2025 |
| MAC Repair Newcastle Limited | Information & communication | 2025 |
| MAC Safety Solutions Ltd | Professional & scientific | 2020 |
| Macaulay & Porteus Management Company Limited | Construction | 2020 |
| Macaw Fintech Ltd | Information & communication | 2025 |
| Macdonald Property North East Limited | Real estate | 2024 |
| Macdonnell Clinical Services Limited | Health & social care | 2026 |
| Mace Marketing Ltd | Professional & scientific | 2024 |
| Maceachern HCH Ltd | Hospitality | 1993 |
| Macgregor (GBR) Limited | Professional & scientific | 2013 |
| Mach II Shipping Limited | Transport & logistics | 1982 |
| Mach One Design Ltd | Professional & scientific | 2019 |
| Machine Care Technology Ltd | Administrative & support | 2021 |
| Mackness Investments Limited | Agriculture & fishing | 2016 |
| Macky Limited | Real estate | 2020 |
| Maclellan Creative Limited | Wholesale & retail | 2020 |
| Maclellan Developments Limited | Real estate | 2022 |
| Macleod & Patterson Limited | Hospitality | 2025 |
| Macleod and Gharini Ltd | Professional & scientific | 2025 |
| Macleod Performance Services Limited | Health & social care | 2024 |
| Macnaughton Mcgregor Limited | Professional & scientific | 2003 |
| Macnor Ltd | Information & communication | 2015 |
| Macresco Limited | Professional & scientific | 2004 |
| Mactech Offshore Services Ltd | Professional & scientific | 2023 |
| MAD Brands Ltd | Hospitality | 2022 |
| MAD Foundation Limited | Education | 2000 |
| MAD Martini Ltd | Wholesale & retail | 2020 |
| MAD Mick Maintenance Ltd | Construction | 2021 |
| Madam Jojo's Property Ltd | Real estate | 2025 |
| Madden's Developments Ltd | Real estate | 2025 |
| Made by Lannyxstudio Limited | Professional & scientific | 2025 |
| Made of Stone Limited | Professional & scientific | 2019 |
| Made Simple Companies Limited | Professional & scientific | 2006 |
| Madhya Services Ltd | Health & social care | 2018 |
| Madina Education Ltd | Other services | 2011 |
| Madina Grill Limited | Wholesale & retail | 2014 |
| Madj Madj Ltd | Professional & scientific | 2025 |
| Madnik Limited | Information & communication | 2019 |
| Maduree Ltd | Construction | 2026 |
| Madventure International Limited | Education | 2004 |
| MAE Luxe Aesthetics Ltd | Other services | 2020 |
| Maersk Training UK Limited | Education | 2006 |
| Magazino Ltd | Wholesale & retail | 2026 |
| Magazinulrodelicioss Ltd | Administrative & support | 2022 |
| Mage Recruitment Ltd | Health & social care | 2026 |