| MKN Electrical Engineering Services Limited | Construction | 2024 |
| Mktestates Ltd | Real estate | 2020 |
| MMG Strategic Advisory Services Ltd | Professional & scientific | 2025 |
| MMR Travel Ltd | Administrative & support | 2026 |
| MMS (NE) Ltd | Hospitality | 2012 |
| MO Bazza's Barbers Ltd | Other services | 2024 |
| Modeno Services Ltd | Construction | 2024 |
| Moksha Foods UK Ltd | Wholesale & retail | 2025 |
| Moloko Fashion Ltd | Wholesale & retail | 2025 |
| Moments Foods Limited | Hospitality | 2023 |
| Mone Solutions Limited | Professional & scientific | 2018 |
| Monitor Coatings Limited | Manufacturing | 2003 |
| Monks Garage Ltd | Wholesale & retail | 2024 |
| Monks Haven Property Management Limited | Households | 2014 |
| Monkseaton Estates Limited | Real estate | 2019 |
| Monometa Limited | Professional & scientific | 2014 |
| Monument (Survey:Design:Build) Ltd | Construction | 2012 |
| Monument Building Maintenance Ltd | Construction | 2023 |
| Monument Contract Flooring Ltd | Construction | 2019 |
| Monument Electrical Engineering Ltd | Construction | 2018 |
| Monument Renewable Solutions Limited | Energy | 2023 |
| Mood Wear Ltd | Information & communication | 2025 |
| Moor Enterprises Ltd | Professional & scientific | 2024 |
| Moore Bennett Ltd | Professional & scientific | 2003 |
| Mooreapartments Ltd | Real estate | 2023 |
| Moray CBD Ltd | Wholesale & retail | 2019 |
| Morse & Stewart Property and Home Improvement Limited | Real estate | 2023 |
| Mortgage Ladies Ltd | Financial services | 2022 |
| Motech Engineering Limited | Manufacturing | 2012 |
| Motor Bodies Hexham Limited | Wholesale & retail | 2025 |
| Mountain Engineering Ltd | Information & communication | 2020 |
| Movantyx Ltd | Manufacturing | 2026 |
| Moxon Hospitality Limited | Hospitality | 2023 |
| Mpath Diagnostics Ltd | Health & social care | 2022 |
| MPE Northeast Ltd | Construction | 2026 |
| MR Pixels Ltd | Wholesale & retail | 2016 |
| MRM Roofing and Property Maintenance Limited | Construction | 2026 |
| MRS Moos Vintage Ltd | Wholesale & retail | 2022 |
| MRS W Bridal Concept Store Ltd | Wholesale & retail | 2021 |
| MS Power Engineering Ltd | Construction | 2024 |
| Msgj Property Ltd | Real estate | 2025 |
| MSH Transport Solutions Limited | Transport & logistics | 2024 |
| MSR Mineral Surveyors Ltd | Real estate | 2025 |
| MTS Homes Ltd | Real estate | 2021 |
| Mumac Consultancy LLP | | 2008 |
| Murphy Stays Ltd | Real estate | 2022 |
| Murray Park Freehold Limited | Real estate | 2024 |
| Murton Equestrian Centre Limited | Arts & recreation | 2006 |
| Murton Farm Estate Limited | Agriculture & fishing | 1944 |
| Mushroom Green Investments Ltd | Real estate | 2021 |
| Music Event Promotions Ltd | Arts & recreation | 2022 |
| Music Shop Ltd | Professional & scientific | 2010 |
| Mussu Ltd | Professional & scientific | 2019 |
| Mwgsss Ltd | Financial services | 2025 |
| My Baan Ltd | Real estate | 2019 |
| My Music Solutions Limited | Information & communication | 2014 |
| My Perspective Ltd | Extraterritorial | 2026 |
| My Retreat Limited | Other services | 2020 |
| My Sport Stay Ltd | Hospitality | 2025 |
| Mybinclean Limited | Other services | 2025 |
| N.E. Display Limited | Administrative & support | 2007 |
| NAB Electro-Technical Ltd | Professional & scientific | 2017 |
| Nabi Platinum Real Estates Ltd | Households | 2025 |
| Nailen Limited | Administrative & support | 2024 |
| Nails by VU Ltd | Other services | 2025 |
| Natec Ltd | Construction | 2020 |
| Natural Witch Ltd | Other services | 2020 |
| Nautical Services Ltd | Professional & scientific | 2018 |
| Nautilus Leisure Limited | Hospitality | 2019 |
| Nayburn Ltd | Real estate | 2024 |
| Nbhd Group Limited | Arts & recreation | 2003 |
| Nbhd Live Ltd | Arts & recreation | 2023 |
| NC Financial Ltd | Financial services | 2018 |
| ND Heating Ltd | Construction | 2024 |
| NDT North East Ltd | Professional & scientific | 2023 |
| NE Artificial Grass Co. Limited | Administrative & support | 2022 |
| NE Consulting Ltd | Real estate | 2021 |
| NE Paint Protection Film Ltd | Wholesale & retail | 2023 |
| NE Rigging Ltd | Mining & quarrying | 2024 |
| NE Transformations Ltd | Arts & recreation | 2022 |
| NE Utility Consulting Ltd | Professional & scientific | 2025 |
| NE29RENEWABLESGROUP Ltd | Professional & scientific | 2026 |
| NE30 Hospitality Limited | Hospitality | 2024 |
| Neat Academy Trust | Education | 2017 |
| Neat Active Limited | Education | 2016 |
| Neera 2 Properties Limited | Real estate | 2025 |
| Neera 3 Properties Limited | Real estate | 2025 |
| Neera 4 Properties Limited | Real estate | 2025 |
| Neera Group Limited | Financial services | 2025 |
| Nemix Ltd. | Information & communication | 2013 |
| Neon Entertainment Limited | Arts & recreation | 2024 |
| Neptuneskyline Ltd | Hospitality | 2026 |
| Nessa Property Ltd | Real estate | 2025 |
| NET 360 CIC | Education | 2021 |
| Netinf Ltd | Professional & scientific | 2014 |
| Network North Networking Limited | Extraterritorial | 2013 |
| Nev-Tech Vehicle Solutions Ltd | Wholesale & retail | 2023 |
| Never ODD Limited | Professional & scientific | 2016 |
| New Bella Rose Flowers Ltd | Wholesale & retail | 2023 |
| New Born Anka Limited | Other services | 2024 |