| Mckenzies Northeast Ltd | Wholesale & retail | 2018 |
| Mclean-Fowler Music Ltd | Information & communication | 2023 |
| Mcmillan Technical Solutions Ltd | Professional & scientific | 2024 |
| MDD Rope Access Limited | Construction | 2024 |
| Meizhufood Limited | Hospitality | 2021 |
| Memories Made Limited | Manufacturing | 2023 |
| Menta Construction Limited | Construction | 2022 |
| Merryn Solutions Ltd | Real estate | 2024 |
| Metric Training Ltd | Arts & recreation | 2025 |
| Millennium Martial Arts Ltd | Arts & recreation | 2013 |
| Millican Residential Group Ltd | Real estate | 2026 |
| Mills Garage Services Ltd | Wholesale & retail | 2024 |
| Millymoos Catering Ltd | Hospitality | 2022 |
| Mitchenson Fabrication & Welding Limited | Manufacturing | 2024 |
| MJ17 Ltd | Extraterritorial | 2021 |
| MJS General Dealers Ltd | Wholesale & retail | 2018 |
| MJW Property Solutions Ltd | Real estate | 2024 |
| MKS Roofers Ltd | Construction | 2023 |
| MLH Technical Solutions Ltd | Manufacturing | 2026 |
| MLN Access Ltd | Construction | 2025 |
| MMA Pipework Limited | Construction | 2023 |
| MNM Property Limited | Real estate | 2020 |
| Mobile Tyres by Andy Ltd | Wholesale & retail | 2026 |
| Moklis & Moklusa Ltd | Professional & scientific | 2026 |
| Mooney Healthcare Limited | Wholesale & retail | 2017 |
| Moonlake Fabrics Limited | Manufacturing | 2017 |
| Moulded Packaging Solutions Ltd | Manufacturing | 2006 |
| Mowlem and Company (Furniture) Limited | Financial services | 2018 |
| Mowlem and Company (London) Limited | Wholesale & retail | 2000 |
| Mowlem and Company (Manufacturing) Limited | Manufacturing | 2017 |
| MPS Northumberland LLP | | 2013 |
| Mqinsights Limited | Wholesale & retail | 2025 |
| MR Shawarma (Blyth) Ltd | Hospitality | 2025 |
| MRH Energy Solutions Ltd | Wholesale & retail | 2020 |
| Mrpv Property Holdings Limited | Real estate | 2026 |
| Mstw Ltd | Hospitality | 2019 |
| MTS Properties (North East) Limited | Real estate | 2023 |
| MTS Roofing (North East) Ltd | Construction | 2015 |
| MVA Financial Consulting Ltd | Professional & scientific | 2024 |
| Myleshousekeeping Ltd | Administrative & support | 2023 |
| N E Burner Installations Ltd | Construction | 2024 |
| N E Fire Limited | Administrative & support | 2010 |
| National Canine Security Ltd | Administrative & support | 2013 |
| NC Consultancy Services Ltd | Information & communication | 2022 |
| NCF (Blyth) Ltd | Wholesale & retail | 2023 |
| NE China Garden Limited | Hospitality | 2023 |
| NE Paving Limited | Manufacturing | 2022 |
| Nefs Ltd | Real estate | 2020 |
| NEK9 Services Ltd | Administrative & support | 2021 |
| Neway Events Ltd | Arts & recreation | 2024 |
| Newsham Garden Limited | Hospitality | 2024 |
| Newsham Garden Takeaway Ltd | Hospitality | 2025 |
| Next Chapter Hub Ltd | Administrative & support | 2025 |
| NG Inc Ltd | Professional & scientific | 2026 |
| Nigel Hedley Holdings Limited | Financial services | 2023 |
| NO.54 With Love Ltd | Wholesale & retail | 2026 |
| Nonleaguezone Limited | Information & communication | 2009 |
| Norabseven Games Limited | Information & communication | 2020 |
| North East Case Management Limited | Extraterritorial | 2002 |
| North East Retro DEN:- Arcade Events Ltd | Administrative & support | 2018 |
| North East Weighing & Calibration Ltd | Manufacturing | 2011 |
| North Eastern Sports Ltd | Wholesale & retail | 2004 |
| North Farm Enterprises Ltd | Administrative & support | 2025 |
| Northburn Technical Services Limited | Manufacturing | 2003 |
| Northern Chair World Limited | Wholesale & retail | 2011 |
| Northern Continental Lines Limited | Transport & logistics | 2000 |
| Northern Digital Marketing Consulting Ltd | Professional & scientific | 2021 |
| Northern Electrical Fire Security Ltd | Construction | 2015 |
| Northern Selling Worxs Limited | Wholesale & retail | 2026 |
| Northern Site Fabrication Limited | Manufacturing | 2016 |
| Northern Spool Base Limited | Manufacturing | 2022 |
| Northmen Roofing Limited | Construction | 2024 |
| Northumberland Escape Rooms Limited | Arts & recreation | 2021 |
| Northumberland Vehicle Maintenance Limited | Wholesale & retail | 2025 |
| Northumberland Warmth Co. Ltd | Construction | 2025 |
| Northumbria Engineering Limited | Manufacturing | 2013 |
| Northumbria Bathrooms and Kitchen Limited | Wholesale & retail | 2023 |
| Northumbria Hot Tubs Ltd | Other services | 2024 |
| Northumbria HSE Ltd | Professional & scientific | 2024 |
| Northumbria Steel Fixing Limited | Construction | 2020 |
| Northumbrian Developments Limited | Real estate | 2021 |
| Northumbrian Electrics Ltd | Professional & scientific | 2026 |
| Northumbrian Properties (NE) Limited | Real estate | 2025 |
| Novobarn Group Ltd | Professional & scientific | 2017 |
| NR Payroll Services Limited | Professional & scientific | 2020 |
| NV Enterprises Limited | Wholesale & retail | 2016 |
| NXT Global Holdings Limited | Financial services | 2024 |
| NXT Homes & Developments Limited | Construction | 2024 |
| O'Connor Management Ltd. | Construction | 2019 |
| Oak Country Club Ltd | Hospitality | 2018 |
| Oakley Civils & Groundworks Ltd | Construction | 2025 |
| Oasis Life Ministeries | Other services | 2024 |
| OBSIDIAN6 Ltd | Construction | 2026 |
| Oddfellows Bandb Limited | Hospitality | 2022 |
| Offshore Renewable Energy Catapult | Professional & scientific | 2003 |
| Offshore Wind Growth Partnership Limited | Professional & scientific | 2019 |
| Offshorecablesolutions Limited | Administrative & support | 2022 |
| Olde Earth Castings Limited | Manufacturing | 2015 |
| Oldgate Finance Limited | Financial services | 2001 |
| Olympus Roofing & Building Contractors Ltd | Construction | 2026 |