| LJ Associate Surveyors Ltd | Professional & scientific | 2025 |
| LJM Investments Ltd | Real estate | 2024 |
| LJP Property Management Ltd | Real estate | 2024 |
| LK9 RAW Ltd | Wholesale & retail | 2024 |
| Lodg Ltd | Real estate | 2024 |
| Logistic North East Training Ltd | Education | 2019 |
| Logistore Northern Ltd | Construction | 2023 |
| Lonebury Limited | | 1987 |
| Lord Nelson JE Ltd | Hospitality | 2025 |
| Lotus Travel North East Ltd | Transport & logistics | 2021 |
| Lovatt Construction Consultants Ltd | Construction | 2021 |
| LOW Fell Cater Limited | Hospitality | 2024 |
| Lspg JV TF Ltd | Real estate | 2022 |
| Lucal Properties Limited | Real estate | 2026 |
| Luckyduckcompetitions Ltd | Wholesale & retail | 2024 |
| Luckyducky Limited | Other services | 2025 |
| Luna Beds Ltd | Wholesale & retail | 2025 |
| M Carrick Property Solutions Ltd | Construction | 2025 |
| M Fischer Ltd | Professional & scientific | 2025 |
| M&D Property Lets Ltd | Real estate | 2022 |
| M.Laidler Contracts Limited | Manufacturing | 2018 |
| M.R.S (NE) Ltd | Real estate | 2023 |
| MA Civils Ltd | Construction | 2022 |
| Macdonald Tree Services Limited | Agriculture & fishing | 2022 |
| Mad-Dog Maguire Ltd | Hospitality | 2024 |
| Madeforu Ltd | Manufacturing | 2023 |
| Mag-Lime UK Limited | Wholesale & retail | 2019 |
| Maher Developments (Levington-Management) Limited | Households | 2004 |
| MAN the Barricades Ltd | Information & communication | 2023 |
| Mandarin Management Services Limited | Administrative & support | 2017 |
| Marchers Holdings Limited | Financial services | 2025 |
| Marchers Management 2 Limited | Professional & scientific | 2012 |
| Marcraft Limited | Administrative & support | 1988 |
| Marex Pizzeria Ltd | Hospitality | 2019 |
| Marine Scaffolding Limited | Construction | 1989 |
| Marshall Construction & Letting Limited | Real estate | 2020 |
| Maruti NE Ltd | Hospitality | 2026 |
| Mason Alexandra Ltd | Other services | 2016 |
| Maughan Properties Limited | Households | 2024 |
| Maverick Productions UK Ltd | Arts & recreation | 2018 |
| Mayor Signature Limited | Administrative & support | 2023 |
| Mbroproperty Ltd | Real estate | 2026 |
| MC Fastcare Ltd | Administrative & support | 2021 |
| MD Commercial Investments Ltd | Real estate | 2019 |
| MDM Safety Services Ltd | Professional & scientific | 2018 |
| Meant to BE Global C.I.C. | Professional & scientific | 2026 |
| Medilogix Global Ltd | Professional & scientific | 2016 |
| Medland Ltd | Administrative & support | 2019 |
| Medrom Care Ltd | Health & social care | 2017 |
| Meet the Makers Ltd | Wholesale & retail | 2021 |
| Merit Lighting Solutions Ltd | Manufacturing | 2025 |
| Messt Ltd | Hospitality | 2023 |
| Midtyne Limited | Transport & logistics | 2025 |
| Migtech IT Solutions Limited | Administrative & support | 2011 |
| Miko Engineering Limited | Manufacturing | 2001 |
| Milan Takeaway Limited | Hospitality | 2002 |
| Milldene Engineering Ltd | Construction | 2016 |
| MKH Process Services Ltd | Manufacturing | 2017 |
| ML Eastway Ltd | Hospitality | 2026 |
| Mmdrd Ltd | Real estate | 2019 |
| MMH Offshore Limited | Other services | 2015 |
| Mmtmc Ltd | Construction | 2024 |
| Mobile Tech Jarrow Ltd | Wholesale & retail | 2021 |
| Monkton PUB Company Ltd | Hospitality | 2025 |
| Monkton Village Assoc Ltd | Other services | 2025 |
| Motion for Mind Fitness CIC | Education | 2025 |
| Motor Marketplace Ltd | Professional & scientific | 2025 |
| Mount Kisco Ltd | Real estate | 2018 |
| Mountain Technical Ltd | Manufacturing | 2025 |
| Moving Forward Consulting Limited | Administrative & support | 2025 |
| MRC Fire Door Inspection Ltd | Construction | 2023 |
| MS Accessible Transport Limited | Transport & logistics | 2025 |
| MTS Consultancy NE Ltd | Other services | 2025 |
| Muddy Fingers Pottery Ltd | Arts & recreation | 2024 |
| Munityx Ltd | Information & communication | 2026 |
| Murciatech Limited | Professional & scientific | 2024 |
| Mush Leisure Limited | Hospitality | 2020 |
| MW Mechanical Solutions Ltd | Professional & scientific | 2021 |
| My Gutter Limited | Administrative & support | 2021 |
| N.E Pavers Ltd | Professional & scientific | 2026 |
| Naafi Cafe’ Limited | Hospitality | 2025 |
| Nadia Nasseh Limited | Construction | 2025 |
| Nash Childcare Limited | Education | 2003 |
| National Mortgage Brokers Ltd | Financial services | 2023 |
| Nattrav Ltd | Transport & logistics | 2012 |
| Nature's Choice Horticulture Ltd | Arts & recreation | 2025 |
| NBI Kitchens & Bedrooms Ltd | Wholesale & retail | 2009 |
| ND Systems Limited | Other services | 2016 |
| NDT Electronic Services Ltd | Professional & scientific | 2007 |
| Nedyalkovi Ltd | Transport & logistics | 2012 |
| Nepr Group Ltd | Water & waste | 2024 |
| Nerc Projects Ltd | Construction | 2023 |
| Nevighburns Ltd | Other services | 2023 |
| New Day Training Ltd | Administrative & support | 2026 |
| New Spring London Ltd | Wholesale & retail | 2025 |
| New Styles With Tiles Limited | Construction | 2025 |
| Newcastle Restaurants Ltd | Hospitality | 2020 |
| Nexgen Innovations North East Ltd | Construction | 2023 |
| Next Generation Concepts Ltd | Administrative & support | 2019 |
| Nichol & Clarke Environmental Services Limited | Other services | 2017 |