| L S Forecourts Ltd | Manufacturing | 2013 |
| L Seaman Electrical Ltd | Professional & scientific | 2025 |
| L Tees Offshore Limited | Administrative & support | 2011 |
| L Tees Properties and Maintenance Ltd | Real estate | 2018 |
| L&B Realty Ltd | Real estate | 2025 |
| L&C Property North East Ltd | Construction | 2026 |
| L&G Instillations Limited | Construction | 2022 |
| L&G Prints Ltd | Manufacturing | 2025 |
| L&K Rope Access Ltd | Construction | 2024 |
| L&L Cable Services Ltd | Construction | 2014 |
| L&L Herman Health Ltd | Health & social care | 2024 |
| L&S Boutique Hair & Beauty Ltd | Manufacturing | 2025 |
| L.A Inkworks Ltd | Professional & scientific | 2025 |
| L.E Matthews Properties Limited | Real estate | 2022 |
| L.M.K Cleaning Ltd | Wholesale & retail | 2021 |
| LA 2 Cumetri Ltd | Hospitality | 2026 |
| LA Autoworks Limited | Wholesale & retail | 2025 |
| LA Events Management and Promotions Ltd | Arts & recreation | 2023 |
| LA Nouva Pizzeria Ltd | Hospitality | 2019 |
| LA Outdoor Services Ltd | Construction | 2022 |
| LA Pizzeria NE Ltd | Hospitality | 2024 |
| Laao Ltd | Other services | 2024 |
| LAB Properties NE Ltd | Real estate | 2026 |
| LAB Sessions Studio Ltd | Information & communication | 2021 |
| Labanese Golden Grill NE Ltd | Hospitality | 2026 |
| Labman Automation Limited | Manufacturing | 1992 |
| Labman Limited | Extraterritorial | 2013 |
| Lacroix Consulting Ltd | Professional & scientific | 2026 |
| Lacy Property Management Ltd | Real estate | 2025 |
| Ladrim Limited | Other services | 1987 |
| LAG Engineering Ltd | Professional & scientific | 2019 |
| Lagganorie Investments Ltd | Real estate | 2025 |
| Laghari Traders Limited | Wholesale & retail | 2026 |
| Laird Solutions Ltd | Administrative & support | 2025 |
| Lakshmi Investment Properties (NE) Ltd | Real estate | 2026 |
| Lamaisah-Ariannah Boutique Limited | Wholesale & retail | 2019 |
| Lambs Site Services Ltd | Professional & scientific | 2025 |
| Lamming Holdings Limited | Financial services | 2024 |
| Lancaster Lrtm Limited | Households | 2019 |
| Land Developments N.E Ltd | Real estate | 2018 |
| Landlord Options Ltd | Real estate | 2016 |
| Landlord Refurbs and Maintenance NE Ltd | Construction | 2025 |
| Landlordrefurbsne Ltd | Construction | 2024 |
| Landscape Matters Holdings Limited | Administrative & support | 2025 |
| Landscape Matters Limited | Administrative & support | 2010 |
| Landstoxx Ltd | Real estate | 2021 |
| Lane House Cleaning Ltd | Administrative & support | 2024 |
| Langage Developments Limited | Real estate | 2014 |
| Langage Energy Park Limited | Construction | 1999 |
| Langage Solar Park Limited | Energy | 2010 |
| Langdon Square Community Centre | Other services | 2012 |
| Langford Training Services Ltd | Health & social care | 2022 |
| Langham Machine Tool Engineers Limited | Manufacturing | 2013 |
| Langlords Ltd | Real estate | 2021 |
| Lansdowne Court Middlesbrough Limited | Households | 2019 |
| Lansdowne Joinery & Building Services Limited | Construction | 2019 |
| LAP Inspection Limited | Other services | 2019 |
| Laraib Travels Ltd | Administrative & support | 2022 |
| Larbay Ideal Concept Limited | Wholesale & retail | 2025 |
| Larc Rigging & Lifting Ltd | Construction | 2023 |
| Last Slice Ltd | Hospitality | 2024 |
| Lasting Powers of Attorney Limited | Other services | 2019 |
| Lata Global Trade Ltd | Wholesale & retail | 2026 |
| Latiftradings Limited | Hospitality | 2025 |
| Latimer Computer Software Limited | Hospitality | 1984 |
| Latinos Teesside & Hispanic Seniors Community Ltd | Education | 2025 |
| Latoben Enterprises Ltd | Real estate | 2025 |
| Lauren Baldwin Ltd | Health & social care | 2022 |
| Lauren Sparkles Ltd | Education | 2024 |
| Lavender Surveying Services Ltd | Administrative & support | 2023 |
| Lavery J Limited | Wholesale & retail | 2025 |
| Lawn Ranger Gardening Ltd | Administrative & support | 2026 |
| Lawson Property Management Limited | Real estate | 2010 |
| Lawson Storage Solutions Ltd | Transport & logistics | 2020 |
| Layers Desserts Ltd | Hospitality | 2020 |
| Lazenby Village Store Ltd | Wholesale & retail | 2018 |
| Lazulife (UK) Limited | Wholesale & retail | 2024 |
| LB Access and Services Limited | Construction | 2018 |
| LB Global Supplies Limited | Wholesale & retail | 2025 |
| LB Project Management NE Ltd | Real estate | 2024 |
| LB Property & Developments Ltd | Real estate | 2022 |
| LBC Welding Ltd | Professional & scientific | 2025 |
| LBW Commercial Properties Ltd | Real estate | 2019 |
| LC Marine Consultancy Limited | Construction | 2018 |
| Lclb Properties Ltd | Real estate | 2026 |
| LCM Arts LLP | | 2021 |
| LCM Motors UK Limited | Wholesale & retail | 2025 |
| LCM Studios Limited | Real estate | 2021 |
| LDB Telecoms Limited | Professional & scientific | 2022 |
| LDW Electrical Ltd | Construction | 2022 |
| Leaders Wholesale Ltd | Wholesale & retail | 2011 |
| League Collective Ltd | Administrative & support | 2024 |
| Leamac Joinery Ltd | Construction | 2020 |
| Learning Key (Training & Consultancy) Limited | Education | 2015 |
| Leasefuture Limited | Real estate | 1987 |
| Leck Contracts Ltd | Construction | 2018 |
| LEE D B Electrical Ltd | Energy | 2015 |
| LEE Dunbar Electrical Services Limited | Professional & scientific | 2009 |
| LEE James Welding Ltd | Manufacturing | 2026 |
| LEE O'Rourke Heating Ltd | Construction | 2023 |