| Kevin Lamb UK Limited | Professional & scientific | 2025 |
| Kiisa Properties Ltd | Real estate | 2022 |
| Kindly Cleaning Ltd | Other services | 2023 |
| Kingswood Property NE Limited | Real estate | 2024 |
| KJD Properties Limited | Real estate | 2003 |
| KJS Floors Limited | Construction | 2010 |
| KM & Sons Electrical Ltd | Construction | 2022 |
| KMC (Northeast ) Limited | Professional & scientific | 2026 |
| KMC Lifting Ltd | Other services | 2017 |
| KMO Estates Limited | Real estate | 2024 |
| KR Integrity Services Ltd | Mining & quarrying | 2021 |
| Kwan (NE) Ltd | Hospitality | 2013 |
| L&K Sales & Marketing Ltd | Administrative & support | 2023 |
| LAJ Mechanical UK Ltd | Manufacturing | 2024 |
| Layer 3 Solutions Ltd | Information & communication | 2019 |
| Learning Labs (UK) Ltd. | Education | 2013 |
| Lee's Rentals Limited | Real estate | 2024 |
| Lee's Transport Services Ltd | Transport & logistics | 2024 |
| Lewell Safety Services Ltd | Administrative & support | 2013 |
| Lift the World Ltd. | Manufacturing | 2017 |
| LIT Synergies Ltd | Professional & scientific | 2024 |
| Little Let's Reads Ltd | Information & communication | 2023 |
| LJR Consultancy Services Limited | Administrative & support | 2023 |
| LMD Commercial Consultancy Limited | Professional & scientific | 2014 |
| LMD Limited | Professional & scientific | 2012 |
| Lmdb Associates Limited | Financial services | 2024 |
| LTT Properties Ltd | Real estate | 2025 |
| Luxe Lounge Hair and Beauty Studio Ltd | Real estate | 2025 |
| M & M Scaffolding Services Limited | Construction | 2022 |
| M Furlong Services Ltd | Manufacturing | 2016 |
| M High Access Solutions Ltd | Other services | 2018 |
| M N Smith Limited | Extraterritorial | 2023 |
| MA Construction Consultants Limited | Construction | 2012 |
| MAC Fitting Ltd | Manufacturing | 2026 |
| Maccessltd Ltd | Administrative & support | 2026 |
| Macdougall Lifting Ltd | Manufacturing | 2013 |
| Mackem Productions Limited | Information & communication | 2024 |
| MAF Properties (NE) Ltd | Real estate | 2025 |
| Magic Mirror Rental Ltd | Arts & recreation | 2026 |
| Magicmiddle Limited | | 1988 |
| MAH NE Ltd | Hospitality | 2018 |
| Main Event Security N.E Ltd | Financial services | 2019 |
| Maison Sepi Ltd | Wholesale & retail | 2026 |
| Malla Property Limited | Real estate | 2024 |
| Manetain Hair and Beauty Ltd | Other services | 2022 |
| Marchers Ltd | Manufacturing | 2020 |
| Maria Walker Interiors Limited | Manufacturing | 2023 |
| Marine Designs Limited | Construction | 2003 |
| Marvin Construction Solutions Ltd | Manufacturing | 2025 |
| Mcdermid Ltd | Transport & logistics | 2020 |
| Mcfarlane Properties Limited | Construction | 2024 |
| Mcvapeuk Ltd | Wholesale & retail | 2019 |
| MEG Care Ltd | Health & social care | 2019 |
| Messenger Holdings Ltd | Professional & scientific | 2007 |
| Michael Anthony Holdings Ltd | Real estate | 2018 |
| Michael Black Design Limited | Professional & scientific | 2014 |
| Mick Furlong Sevices Ltd | Energy | 2023 |
| Mick-Ash Services Ltd | Transport & logistics | 2021 |
| Middleton School of Dance Limited | Education | 2021 |
| Milburn Roofing & Building Specialists Limited | Construction | 2017 |
| Milo Access Platforms Limited | Administrative & support | 2018 |
| Ministry of Palms Ltd | Wholesale & retail | 2018 |
| Mint Stitches CIC | Education | 2024 |
| MK Design Services Limited | Other services | 2017 |
| MM 21 Residential Ltd | Real estate | 2026 |
| MNH Building Services Limited | Construction | 2023 |
| Modern Day Fitness Limited | Education | 2016 |
| Modern Day GK Limited | Health & social care | 2016 |
| Molly Chambers Enterprises Limited | Real estate | 2025 |
| Monarch Home Improvements NE Limited | Other services | 2006 |
| Monist Ltd | Information & communication | 2018 |
| Mons Group Ltd | Construction | 2025 |
| Moonys Scaffolding Limited | Construction | 2025 |
| Mordi Cleaning Services Limited | Administrative & support | 2024 |
| Mountbatten Maintenance Ltd | Construction | 2024 |
| Movement and Media Limited | Arts & recreation | 2026 |
| MQL Limited | Information & communication | 2019 |
| MR CMT Ltd | Manufacturing | 2026 |
| MTB Construction North East Ltd | Construction | 2023 |
| My Defence Limited | Financial services | 2013 |
| My Denton Barbers Limited | Other services | 2024 |
| My Dog Barber (WH) Limited | Other services | 2026 |
| N.M.E Installations Ltd | Administrative & support | 2020 |
| Naga Health Limited | Wholesale & retail | 2025 |
| NE Property Solutions Ltd | Real estate | 2025 |
| New Energy and Building Services Solutions Ltd | Construction | 2021 |
| New Generation Groundworks & Paving Limited | Administrative & support | 2018 |
| New Town MOT Ltd | Wholesale & retail | 2012 |
| Newcastle Fitness College Ltd | Education | 2023 |
| Neworkspace Ltd | Real estate | 2023 |
| Newtown Service Centre Limited | Wholesale & retail | 2020 |
| Nicholas Smith Ltd | Extraterritorial | 2024 |
| Nicholas Thomas William Smith Ltd | Extraterritorial | 2023 |
| Nissi Ltd | Hospitality | 2020 |
| NJP Electrical Solutions Ltd | Construction | 2025 |
| Norman Linsley Limited | Professional & scientific | 2014 |
| North East Couples Therapy Limited | Health & social care | 2021 |
| North East Pets Limited | Wholesale & retail | 2022 |
| North East Quality Tiling Ltd | Construction | 2018 |
| North East Signs Limited | Manufacturing | 2007 |