| Letsquare Ltd | Professional & scientific | 2005 |
| Levelfive Studio Limited | Information & communication | 2026 |
| Levels Gym Newcastle Ltd | Arts & recreation | 2024 |
| Lexentia Advisory Limited | Professional & scientific | 2025 |
| LG Joinery & Construction Ltd | Manufacturing | 2025 |
| LG Property Group Ltd | Real estate | 2026 |
| LGI Music Ltd | Arts & recreation | 2021 |
| Li&Gr Ventures Limited | Real estate | 2024 |
| Liberty Hall Ltd | Education | 2025 |
| Life Alliance Ltd | Financial services | 2018 |
| Life Holistics Limited | Other services | 2019 |
| Life Saving Training Ltd | Education | 2011 |
| Lighthouse Software Labs Ltd | Information & communication | 2025 |
| Lighthouse Talent Research Ltd | Administrative & support | 2025 |
| Lindisfarne College of Theology Ltd | Education | 2009 |
| Lindsay Automation Limited | Professional & scientific | 2024 |
| Lindsway Properties Limited | Real estate | 2021 |
| Links Court (Whitley Bay) Limited | Real estate | 1960 |
| Links Psychology Service Limited | Health & social care | 2012 |
| Linskill Trading Limited | Hospitality | 2015 |
| Little Big Butterfly CIC | Education | 2011 |
| Little Bits Marketing Limited | Professional & scientific | 2023 |
| Little Hubbers Day Nursery Limited | Health & social care | 2018 |
| Little Lounge Mobile Soft Play Ltd | Arts & recreation | 2025 |
| Little Mexico Hexham Limited | Hospitality | 2022 |
| Liveasy Ltd | Health & social care | 2007 |
| Living Archive Limited | Information & communication | 2020 |
| Living to Learn North East Ltd | Education | 2019 |
| Living to Learn Skills Ltd | Education | 2020 |
| Living to Learn Training Ltd | Education | 2020 |
| Lizosoft Ltd | Wholesale & retail | 2021 |
| LJ Renewables Ltd | Professional & scientific | 2023 |
| LJC Property Services Ltd | Real estate | 2022 |
| LJK Academy Ltd | Education | 2025 |
| LJK Aesthetics Ltd | Other services | 2018 |
| LKH Homes Limited | Real estate | 2024 |
| LKH Safety Consulting Ltd | Professional & scientific | 2024 |
| Lloyd Quinn Engineering Ltd | Construction | 2015 |
| Lmbs North Ltd | Financial services | 2025 |
| Localbusinesshelp.Ai Ltd | Administrative & support | 2025 |
| Lofthouse Prints Ltd | Manufacturing | 2025 |
| Logic Newcastle Limited | Professional & scientific | 2025 |
| Logistics Skills & Consultancy (Midlands) Ltd | Education | 2015 |
| Logistics Skills & Consultancy Ltd | Transport & logistics | 2011 |
| Lokco Productions Ltd | Arts & recreation | 2021 |
| Longsands Consultants Limited | Professional & scientific | 2025 |
| Longsands Customs Consultancy Ltd | Professional & scientific | 2021 |
| Longsands Engineering Ltd | Professional & scientific | 2017 |
| Longsands Engineering Minor Works Ltd | Professional & scientific | 2021 |
| Longsands Financial Planning Ltd | Professional & scientific | 2019 |
| Longsands Heating and Plumbing Ltd | Construction | 2021 |
| Longsands Limited | Hospitality | 2003 |
| Longsands Properties Ltd | Real estate | 2016 |
| Longsands Services Ltd | Administrative & support | 2012 |
| Lorraine Crosby Productions Ltd | Information & communication | 2013 |
| LOU Laggan Coaching Limited | Professional & scientific | 2018 |
| LOW Lights Tavern Limited | Hospitality | 2016 |
| LOW Quay Ltd | Real estate | 2025 |
| Lowden ENG Ltd | Construction | 2023 |
| Loyal Quays Local Store Limited | Wholesale & retail | 2023 |
| Lozza Productions Ltd | Professional & scientific | 2019 |
| LPC (North Shields) Limited | Manufacturing | 2024 |
| LPD North East Limited | Manufacturing | 2019 |
| Lrpt Limited | Other services | 2022 |
| Ls&C Driver Training Ltd | Education | 2025 |
| LTL (NE) Limited | Education | 2026 |
| Luckin Coffee Limited | Hospitality | 2025 |
| Luke Accountancy Limited | Professional & scientific | 2024 |
| Luke Latimer Ltd | Professional & scientific | 2025 |
| Lumac Holdings Limited | Financial services | 2020 |
| Lumina Physiotherapy & Pilates Limited | Health & social care | 2025 |
| Lumley Wilkinson Developments Ltd | Construction | 2016 |
| Lupus Aquae Ltd | Real estate | 2024 |
| Lush Logistics Limited | Transport & logistics | 2022 |
| Lyons Flooring Ltd | Construction | 2025 |
| M a and I G Corner Limited | Hospitality | 2002 |
| M D P Joinery and Shopfitting Ltd | Construction | 2015 |
| M J Grady Ltd | Administrative & support | 2025 |
| M Rose Limited | Information & communication | 2026 |
| M&Rw Limited | Real estate | 2025 |
| M&S Richards Ltd | Hospitality | 2025 |
| M. a. M. a. Homes Limited | Real estate | 2018 |
| M.& M.Value Limited | Wholesale & retail | 1960 |
| M.G. Joiners & Builders Ltd | Construction | 2006 |
| M.J. Baker Foodservice Limited | Hospitality | 1998 |
| M.R.C Financial Planning Ltd | Professional & scientific | 2020 |
| M10 Missions | Education | 2011 |
| MA Fabrication Solutions Ltd | Manufacturing | 2021 |
| Maanvi’S Righteous Retail Limited | Wholesale & retail | 2023 |
| Mabhena Limited | Health & social care | 2015 |
| Macallister & Wolf Ltd | Professional & scientific | 2024 |
| Mackay & Co Limited | Real estate | 2006 |
| Mackay Macpherson Corporate Services Limited | Professional & scientific | 2001 |
| Mackay Macpherson Investment Management LLP | | 2005 |
| Macleod Trotter Books Limited | Information & communication | 2011 |
| Macqueen Consultancy Ltd | Professional & scientific | 2010 |
| MAD Munchies Ltd | Hospitality | 2025 |
| Madame Beauty (NE) Limited | Other services | 2024 |
| Madame TAN (NE) Ltd | Other services | 2023 |
| Madebuy Ltd | Wholesale & retail | 2010 |