| MRT North East Ltd | Wholesale & retail | 2017 |
| Mulhall Properties Ltd | Real estate | 2021 |
| Multans Tandoori Limited | Hospitality | 2025 |
| Muthukk Limited | Wholesale & retail | 2025 |
| MVB Industries Limited | Construction | 2018 |
| My Home Creations Ltd | Construction | 2025 |
| My Medical Supplies Ltd | Wholesale & retail | 2026 |
| Mylar Specialty Films UK Limited | Manufacturing | 1999 |
| Myriad Enterprise LLP | | 2021 |
| N J Drury Properties Limited | Real estate | 2017 |
| N&H Property Investment Limited | Real estate | 2019 |
| N.C. Health, Safety & Environmental Advisory Services Ltd | Administrative & support | 2017 |
| N.E.B.C Services Ltd | Construction | 2021 |
| Nasr Optics Limited | Energy | 2008 |
| NAT Mitchell Independent Funeral Services Ltd | Other services | 2025 |
| National Safety Passport Limited | Education | 2026 |
| Natural Partners Limited | Information & communication | 1999 |
| NCS Health and Wellbeing Services Ltd | Health & social care | 2025 |
| NE AJ Property Ltd | Real estate | 2025 |
| NEED2KNOW Consultantcy Limited | Information & communication | 2025 |
| Nelson Terrace Management Company Limited | Other services | 2006 |
| Nenf Limited | Manufacturing | 2026 |
| NER Brek,Limited | Real estate | 1948 |
| NET-3.CO.UK Limited | Administrative & support | 2005 |
| Neurosense Teesside Ltd | Health & social care | 2025 |
| New Food Stall Ltd | Hospitality | 2025 |
| New Marske Community Group Ltd | Other services | 2013 |
| New Shanghai 109 Ltd | Hospitality | 2023 |
| New Yorker 64 Pizzeria Ltd | Hospitality | 2026 |
| New Yorker Pizzeria Ltd | Hospitality | 2023 |
| Newcomen Community Residents Limited | Other services | 2025 |
| NG Building Ltd | Construction | 2025 |
| NGP Inspection Ltd | Professional & scientific | 2013 |
| Nicola Swales - Health and Wellbeing Services Ltd | Health & social care | 2026 |
| Nicoss Property Services Ltd | Real estate | 2020 |
| NKP Draughting Ltd | Professional & scientific | 2013 |
| NKT HVC Ltd. | Professional & scientific | 2016 |
| NL Management Solutions Ltd | Professional & scientific | 2025 |
| NO More MOO Ltd | Manufacturing | 2024 |
| Nook & Nestle Ltd | Wholesale & retail | 2025 |
| Nora Soloutions Ltd | Hospitality | 2023 |
| Normanby Laboratory Services Limited | Manufacturing | 2007 |
| North East Coast Events Ltd | Arts & recreation | 2016 |
| North East Food Technology Services Ltd | Professional & scientific | 2007 |
| North East Groundworks Limited | Administrative & support | 2025 |
| North East Seafoods Limited | Manufacturing | 2020 |
| North Yorkshire Retroworks Ltd | Wholesale & retail | 2024 |
| Northcote Clark Limited | Health & social care | 2018 |
| Northern Cladders Ltd | Construction | 2024 |
| Northern Design Limited | Professional & scientific | 2003 |
| Northern Renewable Centre Limited | Wholesale & retail | 2022 |
| Nova Client Management Ltd | Water & waste | 2025 |
| NPC Training Ltd | Administrative & support | 2010 |
| Nptone Limited | Manufacturing | 2022 |
| NRC Franchise Ltd | Wholesale & retail | 2026 |
| NRC Training Limited | Wholesale & retail | 2023 |
| NRF Lettings Ltd | Real estate | 2026 |
| NS Restaurant Redcar Limited | Hospitality | 2025 |
| NT Support Services Ltd | Transport & logistics | 2018 |
| NWA Properties Limited | Real estate | 2015 |
| NY Mechanical Engineering Ltd | Professional & scientific | 2022 |
| O Watson Property Management Limited | Real estate | 2024 |
| O'Donovan Wind Ltd | Professional & scientific | 2022 |
| Oak Road Surveying Limited | Professional & scientific | 2018 |
| Odin Power and Energy Limited | Water & waste | 2025 |
| Odin Property Investments Ltd | Real estate | 2023 |
| Ofan Ltd | Professional & scientific | 2025 |
| OH, the Places You'Ll Go... Ltd | Education | 2022 |
| Omega Vibes Ltd | Hospitality | 2026 |
| Omnia Inclusion Ltd | Information & communication | 2026 |
| ON the B4NK Ltd | Administrative & support | 2022 |
| ON the Move North East Property Maintenance Limited | Administrative & support | 2025 |
| Orbital Marketing Ltd | Information & communication | 2025 |
| Orchard Kitchen Ltd | Hospitality | 2019 |
| Origami Agency Ltd. | Information & communication | 2019 |
| Ormerod Civils Ltd | Construction | 2024 |
| Ortpark Property Ltd | Real estate | 2024 |
| Osbornesproperty Limited | Real estate | 2025 |
| Other Records Limited | Professional & scientific | 1997 |
| OTR Travel Ltd | Administrative & support | 2025 |
| OUT of Reach Ltd | Professional & scientific | 2025 |
| Overfield Kitchens Limited | Construction | 2011 |
| OWR Investment Properties Ltd | Real estate | 2025 |
| P J Ward Electrical Services Ltd | Construction | 2025 |
| P R Lifting Ltd | Professional & scientific | 2025 |
| P&R Property Investments Ltd | Real estate | 2021 |
| P. Hoggart Haulage Limited | Transport & logistics | 1993 |
| P.C. Tech (Redcar) Limited | Information & communication | 2014 |
| P4 Homes Ltd | Real estate | 2025 |
| Papeto Pizzeria Ltd | Hospitality | 2024 |
| Parkway Cleaning Services Ltd | Administrative & support | 2023 |
| Paul Chaplin Ltd | Professional & scientific | 2024 |
| Paul Rodgers Joinery Ltd | Construction | 2015 |
| Pavilion Dome Ltd | Real estate | 2024 |
| Paws 'N' Claws Grooming Ltd | Other services | 2015 |
| PB Joinery & Maintenance Ltd | Construction | 2016 |
| PB Properties North East Limited | Real estate | 2025 |
| PDL Electrical Ltd | Other services | 2016 |
| Pearce's Homes Ltd | Real estate | 2023 |
| Pearson Properties North East Ltd | Real estate | 2023 |