| Meadowville Limited | Real estate | 2020 |
| Meadway News North East Limited | Wholesale & retail | 2014 |
| Meal Night Limited | Hospitality | 2023 |
| Meal on the Wheels 2025 Limited | Hospitality | 2025 |
| Mean Bean Coffee Company Ltd | Manufacturing | 2019 |
| Mean Eyed Cat Limited | Hospitality | 2012 |
| Mearoo Ltd | Households | 2023 |
| Mears IT Limited | Information & communication | 2013 |
| Meat Restaurant Outlet Limited | Hospitality | 2020 |
| Meat:Stack Grainger Ltd | Hospitality | 2017 |
| Meat:Stack Holdings Limited | Hospitality | 2019 |
| Meat:Stack Leeds Limited | Hospitality | 2021 |
| Meat:Stack Newcastle Limited | Hospitality | 2019 |
| Meat:Stack Popups Limited | Hospitality | 2016 |
| MEC Foundation UK | Other services | 2014 |
| MEC Housing Ltd | Real estate | 2025 |
| Meccarama Limited | Real estate | 1989 |
| Mech Tech Services Limited | Professional & scientific | 2025 |
| Mechano Ltd | Professional & scientific | 2019 |
| Mechatronics Solutions Limited | Information & communication | 2023 |
| Mechtec Ltd | Construction | 2021 |
| Mectronic Holding Limited | Financial services | 2022 |
| Medaccess Services Limited | Health & social care | 2014 |
| Medbridge Global Ltd | Wholesale & retail | 2026 |
| Medburn Close Management Company Limited | Real estate | 2022 |
| Medburn Developments Holdings Ltd | Financial services | 2024 |
| Medburn Developments Land and Property Ltd | Construction | 2024 |
| Medburn Developments Ltd | Construction | 2021 |
| Medburn Estates Limited | Real estate | 2003 |
| Medburn Park Management Company Limited | Real estate | 2019 |
| Medburn Property Holdings Ltd | Real estate | 2019 |
| Medburn Property Ltd | Real estate | 2015 |
| Medburn Property Number 3 Ltd | Real estate | 2022 |
| Medburn Property Number 4 Ltd | Real estate | 2024 |
| Medburn Rosebud Limited | Construction | 2026 |
| Medcan Clinicians Society CIC | Administrative & support | 2019 |
| Medellin Newcastle Limited | Hospitality | 2023 |
| MEDH9 Limited | Information & communication | 2021 |
| Medhealth Innovations Ltd | Wholesale & retail | 2026 |
| Media and General Consulting Services (UK) Limited | Professional & scientific | 2015 |
| Media Borne Limited | Information & communication | 2018 |
| Media Makers Meet - MX3 Ltd | Professional & scientific | 2021 |
| Media Only Limited | Extraterritorial | 1990 |
| Mediafabric Ltd | Information & communication | 2021 |
| Mediatic Ltd | Professional & scientific | 2025 |
| Mediation Medics Limited | Professional & scientific | 2015 |
| Medibiotix Limited | Professional & scientific | 2020 |
| Medic-Health Ltd | Health & social care | 2023 |
| Medical Aesthetics Training Academy Limited | Health & social care | 2026 |
| Medical Education & Consultancy Limited | Health & social care | 2023 |
| Medical Reporting Solutions Limited | Health & social care | 2015 |
| Medicentre (Newcastle) Limited | Wholesale & retail | 2007 |
| Medicine Stop Limited | Wholesale & retail | 2014 |
| Medicta ST Ltd | Wholesale & retail | 2023 |
| Medilaris Services Limited | Health & social care | 2020 |
| Medilive Limited | Health & social care | 2018 |
| Medintegrity Consulting Ltd | Professional & scientific | 2025 |
| Medisol Limited | Real estate | 1994 |
| Meditait Ltd | Health & social care | 2026 |
| Meditation Teacher College | Education | 2021 |
| Meditech Solutions Ltd | Information & communication | 2016 |
| Meditrics Ltd | Information & communication | 2020 |
| Medoled Technologies Ltd | Information & communication | 2020 |
| Medpersonnel Limited | Administrative & support | 2022 |
| Medway Exchange Ltd | Professional & scientific | 2013 |
| MEE & MEE Limited | Real estate | 2024 |
| Meecham Consulting Ltd | Professional & scientific | 2024 |
| Meeradhya Limited | Real estate | 2024 |
| Meerkat Developments Ltd | Households | 2022 |
| Meerkat Film Productions Ltd | Information & communication | 2006 |
| Meet at Twelve Ltd | Hospitality | 2021 |
| Mega Burgers NE Ltd | Hospitality | 2024 |
| Mega Cctv Ltd | Administrative & support | 2017 |
| Mega Tech Master Ltd | Wholesale & retail | 2024 |
| Megas Union Global Ltd | Information & communication | 2024 |
| MEI IT Limited | Information & communication | 2021 |
| MEI MEI Heaton Limited | Hospitality | 2015 |
| MEI SAN Ltd | Hospitality | 2010 |
| Meixiya Newcastle Ltd | Hospitality | 2024 |
| Mejw Limited | Real estate | 2021 |
| MEK Technology Limited | Information & communication | 2024 |
| Meklec Travel Ltd | Transport & logistics | 2017 |
| MEL & Jones Ltd | Health & social care | 2016 |
| MEL Millis Limited | Wholesale & retail | 2012 |
| Melbury Investments Limited | Real estate | 2021 |
| Melbury Property Limited | Real estate | 2012 |
| Meldon Property Investments Ltd | Households | 2020 |
| Melete Energy Limited | Professional & scientific | 2025 |
| Melissa Roberts Limited | Administrative & support | 2010 |
| Melody Mobile Repairs Ltd | Wholesale & retail | 2021 |
| Melrose CEC Limited | Wholesale & retail | 2022 |
| Melton Financial Ltd | Financial services | 2023 |
| Melton Green Limited | Construction | 2016 |
| Mema Asset Management Ltd | Real estate | 2024 |
| Memory Lane Productions CIC | Information & communication | 2020 |
| Mena Connect Ltd | Information & communication | 2020 |
| Mendoza Invests Limited | Real estate | 2019 |
| Mensley Ltd | Construction | 2016 |
| Menta Property Maintenance Ltd | Administrative & support | 2017 |
| Mental Health Concern Ltd | Financial services | 2022 |