| Mortley Estates Limited | Real estate | 2006 |
| Most E & I Limited | Real estate | 2015 |
| Motak Global Limited | Transport & logistics | 2026 |
| Moto Club Ltd | Wholesale & retail | 2025 |
| Motor M8 Limited | Wholesale & retail | 2023 |
| Moulds and Studs Ltd | Wholesale & retail | 2025 |
| Mowden Park Estate Company Limited | Real estate | 1967 |
| MPH Restaurant (NE) Limited | Hospitality | 2018 |
| MPS Reactors Limited | Manufacturing | 2007 |
| MQH Services Ltd | Construction | 2014 |
| MR Aujla Ltd | Hospitality | 2024 |
| MR Wheels Ltd | Wholesale & retail | 2018 |
| MRJ Building & Maintenance Limited | Construction | 2020 |
| Mrmeats Limited | Hospitality | 2025 |
| MRW Plant Safety Training Limited | Other services | 2015 |
| MS Convenience Ltd | Wholesale & retail | 2026 |
| MS Post and Trading Ltd | Wholesale & retail | 2015 |
| MSC IT Solutions Ltd | Information & communication | 2011 |
| MSP Legal Services LLP | | 2007 |
| MT Rescue Services Ltd | Education | 2024 |
| MT Sensory Ltd | Health & social care | 2022 |
| Mtaa Engineering Limited | Construction | 2015 |
| Mtal Ltd | Construction | 2014 |
| Muir Inspection Services Ltd | Professional & scientific | 2012 |
| Muirhead ALL in One Limited | Wholesale & retail | 2024 |
| Mulgrave Carpets Limited | Wholesale & retail | 2003 |
| Multitec Solutions Ltd | Real estate | 2018 |
| Mumbai Hartlepool Ltd | Hospitality | 2024 |
| Mumbai Indian Restaurant Ltd | Hospitality | 2019 |
| Mummy Chelle Jewelries Ltd | Wholesale & retail | 2023 |
| Muncheez Fastfood Ltd | Hospitality | 2020 |
| Murfitt Electrical Ltd | Wholesale & retail | 2026 |
| Murray Engineering Limited | Professional & scientific | 2019 |
| Murrell Hill Farm Limited | Real estate | 2022 |
| MVA Services Ltd | Manufacturing | 2017 |
| MVS Group Ltd | Wholesale & retail | 2013 |
| MW Medical Services Limited | Health & social care | 2016 |
| MW Safety Consultants Limited | Professional & scientific | 2011 |
| Mwms Commercial Management Ltd | Professional & scientific | 2007 |
| MWS First AID Limited | Education | 2006 |
| My Bedtime IS Limited | Hospitality | 2024 |
| My Compute Time IS Limited | Information & communication | 2023 |
| My Figaros 1 Ltd | Hospitality | 2025 |
| My Time IS Limited | Information & communication | 2024 |
| My Tine IS Limited | Wholesale & retail | 2021 |
| Mycompanioncare Limited | Health & social care | 2026 |
| Myers Insulation Ltd | Professional & scientific | 2025 |
| Myregenconsultancy Ltd | Professional & scientific | 2026 |
| Mystery Gamedays Ltd | Administrative & support | 2023 |
| N & a Skidmore Roofing Contractors Ltd | Construction | 2015 |
| N Costel Solutions Ltd | Administrative & support | 2021 |
| N D Simpson & Sons Haulage Limited | Transport & logistics | 2019 |
| N E European Recruitment Limited | Administrative & support | 2007 |
| N Flounders Offshore Lifting Limited | Manufacturing | 2024 |
| N Stump Holding Limited | Administrative & support | 2026 |
| N&T Civils Ltd | Construction | 2015 |
| N&T Groundwork Services Limited | Construction | 2018 |
| N. P. C. S. Limited | Manufacturing | 2007 |
| Nabiabaad Properties Ltd | Real estate | 2025 |
| NAD LAB UK Ltd | Wholesale & retail | 2019 |
| Nahm Ltd | Wholesale & retail | 2025 |
| Nail Medicine Ltd | Wholesale & retail | 2024 |
| Naira Tandoori Ltd | Hospitality | 2020 |
| Naisberry Park Builders Ltd | Construction | 2024 |
| Natara Global Limited | Financial services | 2023 |
| Nathan Boagey Ltd | Construction | 2025 |
| Nathanriches Limited | Construction | 2024 |
| National Heights Rope Access Ltd | Construction | 2024 |
| National Jointing Ltd | Construction | 2018 |
| National Jointing Services Ltd | Construction | 2020 |
| National Solar Solutions Limited | Construction | 2026 |
| Natoli Leisure Limited | Arts & recreation | 2009 |
| Nawaz G Ltd | Wholesale & retail | 2026 |
| Nazary NAK Muay Thai C.I.C. | Public administration | 2024 |
| NCE Building and Maintenance Services Limited | Construction | 2016 |
| ND Services Ltd | Professional & scientific | 2020 |
| NDC College Ltd | Arts & recreation | 2023 |
| NDL Safety Limited | Other services | 2015 |
| NE Civils Ltd | Construction | 2021 |
| NE Commercial Services Limited | Professional & scientific | 2018 |
| NE Drain Services Ltd | Water & waste | 2026 |
| NE Hire (North East) Ltd | Administrative & support | 2025 |
| NE Plant Ltd | Agriculture & fishing | 2017 |
| NE Security Ltd | Administrative & support | 2012 |
| NE Security Services Ltd | Administrative & support | 2015 |
| NE1 Residential & Commercial Ltd | Construction | 2025 |
| Neca Solutions Limited | Professional & scientific | 2005 |
| Nedrains Ltd | Other services | 2024 |
| Nee&Pm Limited | Professional & scientific | 2018 |
| Nehvservices Ltd | Administrative & support | 2026 |
| Neil Briggs Financial Services Ltd | Professional & scientific | 2019 |
| Neilanthonycooke Limited | Construction | 2017 |
| Nelson Bridges Ltd | Administrative & support | 2019 |
| Nerth Foods Ltd | Wholesale & retail | 2025 |
| Nests Management Services Limited | Administrative & support | 2013 |
| NET Train Ltd | Professional & scientific | 2025 |
| Network Engineering Services Limited | Construction | 2013 |
| Neuroaware CIC | Information & communication | 2026 |
| Neuronormity Ltd | Health & social care | 2025 |
| Nevezza Holdings Ltd | Professional & scientific | 2023 |