| Lujo Installation Services Ltd | Construction | 2026 |
| Lulu's Lounge Limited | Other services | 2017 |
| Luna BLU NE Community Interest Company | Education | 2024 |
| Luna Private Hire Ltd | Other services | 2023 |
| Luno Hygiene Ltd | Wholesale & retail | 2023 |
| Luxepixelprints Ltd | Wholesale & retail | 2025 |
| LX Media Services Ltd | Other services | 2025 |
| L’Ouvrier Fragrance Ltd | Wholesale & retail | 2024 |
| M & C HOY Limited | Wholesale & retail | 2014 |
| M & D (Butchers) Limited | Wholesale & retail | 2010 |
| M & J Cars NE Ltd | Wholesale & retail | 2019 |
| M & L Hatch Properties Ltd | Real estate | 2021 |
| M .T .O Global Cleaning Ltd | Administrative & support | 2026 |
| M M Offshore Reps Limited | Construction | 2011 |
| M Mccarthy Building and Maintenance Ltd | Construction | 2009 |
| M Pearson Services Limited | Other services | 2017 |
| M U PMC Ltd | Other services | 2024 |
| M&K Accountant Ltd | Professional & scientific | 2013 |
| M&M Offshore Ltd | Other services | 2022 |
| M-Technic Limited | Administrative & support | 1995 |
| M.A.C Industrial Services Ltd | Construction | 2019 |
| M.A.Holmes Construction Upvc Specialist Ltd | Other services | 2015 |
| M.E Rope Access Ltd | Construction | 2017 |
| M.I. Dickson Limited | Manufacturing | 1953 |
| M.Young Inspection Services Ltd | Other services | 2015 |
| MA South Shields Ltd | Hospitality | 2025 |
| MAC Property Solutions LLP | | 2016 |
| MAD 4 Pets Limited | Wholesale & retail | 2014 |
| MAD Jackal Games Ltd | Information & communication | 2020 |
| Madyan Tours Ltd | Administrative & support | 2007 |
| Magic Blue Cleaning Service Ltd | Wholesale & retail | 2020 |
| MAH Publishings Ltd | Information & communication | 2020 |
| Mailes NE Ltd | Hospitality | 2023 |
| Majestic Ventures (UK) Limited | Construction | 2004 |
| Maka Developments Limited | Real estate | 2013 |
| Malboro Limited | Other services | 2025 |
| Mandale Commercial NE Ltd | Real estate | 2025 |
| Mandale Retail Ltd | Wholesale & retail | 2025 |
| Manfeld Ltd | Real estate | 2015 |
| Manor Court Maintenance Limited | Real estate | 1987 |
| Manosun Limited | Manufacturing | 2020 |
| Mansa NE Ltd | Hospitality | 2023 |
| MAR Y Tierra Ltd | Hospitality | 2025 |
| Marco Properties Ltd | Real estate | 2023 |
| Marine City Takeaway Ltd | Hospitality | 2025 |
| Mariners Park Estate North Management Company Limited | Households | 2014 |
| Mariners Park Estate South Management Company Limited | Households | 2014 |
| Marios Pizza & Grill Ltd | Hospitality | 2026 |
| Maritime Shipping and Logistics Ltd | Transport & logistics | 2018 |
| Maritimum Estates Ltd | Real estate | 2025 |
| Mark Earnden Enterprises Limited | Professional & scientific | 2018 |
| Mark Inting Limited | Health & social care | 2022 |
| Market Dock Maintenance (NO 3) Limited | Real estate | 1999 |
| Market Dock Maintenance (NO. 1) Limited | Real estate | 1997 |
| Market Dock Maintenance (NO.2) Limited | Professional & scientific | 2004 |
| Marketing Muscle Ltd | Administrative & support | 2013 |
| Marking Therapy Ltd | Health & social care | 2023 |
| Marr Hospitality Ltd | Hospitality | 2025 |
| Marsden 64 Limited | Extraterritorial | 2013 |
| Marsden Bay Electrical Services Limited | Construction | 2021 |
| Marshall Hall Levy Limited | Professional & scientific | 2006 |
| Martin Builders Plumbing & Heating Limited | Construction | 2025 |
| Martose Flooring Limited | Wholesale & retail | 2008 |
| Marys Chippy Ltd | Hospitality | 2023 |
| MAS Industrial Services Ltd | Construction | 2017 |
| MAS Rentals Limited | Real estate | 2024 |
| Mash Barbers Ltd | Other services | 2025 |
| Mason Morton Ltd | Financial services | 2014 |
| Masons Barbering Academy Ltd | Other services | 2023 |
| Mass Construction (NE) Ltd | Construction | 2025 |
| Matsons Plumbing & Heating Ltd | Construction | 2015 |
| MAX Carr Investments Limited | Real estate | 2023 |
| Maxios Tech Ltd | Wholesale & retail | 2025 |
| MB Electrical and Security Systems Ltd | Construction | 2025 |
| MC Services NE Ltd | Administrative & support | 2023 |
| Mcclean QS Limited | Administrative & support | 2016 |
| Mcclements Optical Ltd | Health & social care | 2013 |
| Mccluskey's Passenger Services Ltd | Transport & logistics | 2025 |
| Mcfee Limited | Hospitality | 2019 |
| Mcmann Construction Limited | Construction | 2025 |
| ME Mortgage Solutions Limited | Financial services | 2023 |
| Mechplant (North East) Limited | Administrative & support | 2002 |
| Mechpro Systems Limited | Manufacturing | 2023 |
| Medics of Tyneside Limited | Health & social care | 2003 |
| Megan Management Ltd | Information & communication | 2026 |
| Meldon Village Storage and Drying Limited | Agriculture & fishing | 2000 |
| Melts With SAM Ltd | Wholesale & retail | 2025 |
| Merchan Rogel Ltd | Hospitality | 2025 |
| Meridia Global Ltd | Wholesale & retail | 2025 |
| Meridian House Management Limited | Administrative & support | 2000 |
| Metalpoint Limited | Wholesale & retail | 1982 |
| Metec Cathodic Protection Limited | Manufacturing | 2016 |
| Metis Training and Development Limited | Professional & scientific | 2025 |
| Metro News Limited | Wholesale & retail | 2025 |
| Mews Ltd | Wholesale & retail | 2014 |
| MGS Drone Surveying Ltd | Professional & scientific | 2026 |
| MHA PMC Ltd | Other services | 2019 |
| MIA Automotive Ltd | Wholesale & retail | 2026 |
| Michael Callaghan Irata Ltd | Construction | 2025 |
| Michael James Conroy Landscaping Ltd | Administrative & support | 2022 |