| Loughran Property Ltd | Households | 2025 |
| Louis James Management Services Limited | Professional & scientific | 2015 |
| Louise Biswas Limited | Wholesale & retail | 2025 |
| Louise Brannigan Limited | Professional & scientific | 2026 |
| Louise Engineering Limited | Manufacturing | 1970 |
| Lounch Ltd | Manufacturing | 2026 |
| Lounge Afrique Ltd | Hospitality | 2025 |
| Loutom Media Ltd | Information & communication | 2017 |
| Love Comms Ltd | Professional & scientific | 2025 |
| Love Laser North East Ltd | Other services | 2024 |
| Loveataly Limited | Hospitality | 2022 |
| LOW CAL Llewellyns Ltd | Hospitality | 2019 |
| Lowbridge Contracts Limited | Other services | 2018 |
| Lowe & Simpson Group Holdings Limited | Financial services | 2024 |
| Lowe & Simpson Group Limited | Manufacturing | 1979 |
| Lowfields Engineering Limited | Administrative & support | 2019 |
| LP Facades Installs & Professional Trades Ltd | Construction | 2019 |
| LP Forex Trading Limited | Financial services | 2025 |
| LP HSE Solutions Limited | Public administration | 2019 |
| LP Operators Ltd | Construction | 2016 |
| LPH Safety Ltd | Construction | 2023 |
| LPJ Developments Limited | Construction | 2015 |
| Lptktrading Ltd | Professional & scientific | 2026 |
| LPV Services Ltd | Professional & scientific | 2025 |
| LR Property Investments (NE) Ltd | Hospitality | 2025 |
| LRE Plant and Agri Limited | Wholesale & retail | 2023 |
| LS Properties (North East) Limited | Real estate | 2021 |
| LS Scaffold (North East) Ltd | Construction | 2018 |
| LS Solutions Accountancy Services Limited | Administrative & support | 2026 |
| LSM Consultancy Limited | Administrative & support | 2023 |
| LT Property Rentals Ltd | Real estate | 2023 |
| LT Scaffolding Services Ltd | Construction | 2019 |
| LTA Access Property Limited | Administrative & support | 2016 |
| LTC Quality Services Ltd | Professional & scientific | 2024 |
| LTC Trading Ltd | Administrative & support | 2020 |
| LTF Group Ltd | Wholesale & retail | 2025 |
| Ltmac Limited | Professional & scientific | 2025 |
| Ltpt Limited | Health & social care | 2022 |
| LTW Bolting Solutions Limited | Construction | 2015 |
| Ltyplantservices Ltd | Manufacturing | 2025 |
| Lubda Property Ltd | Real estate | 2024 |
| Lucava Solutions Limited | Real estate | 2025 |
| Lucid Software Limited | Professional & scientific | 1988 |
| Lucky Cat 125 Limited | Hospitality | 2025 |
| Lucky House Fast Food Limited | Hospitality | 2016 |
| Lucky Lucianos 4U Ltd | Hospitality | 2025 |
| Lucky's Play Barn Limited | Hospitality | 2016 |
| Lucy Wells Consultancy Limited | Professional & scientific | 2008 |
| Lukasso Limited | Real estate | 2025 |
| Luke for Solutions Limited | Financial services | 2014 |
| LUKEB88 Limited | Manufacturing | 2021 |
| Lula Marine Limited | Transport & logistics | 2012 |
| Lumalane Limited | Wholesale & retail | 2025 |
| Lumeniq Technologies Ltd | Information & communication | 2026 |
| Luna Van Conversions Limited | Manufacturing | 2022 |
| Luna Vans Ltd | Manufacturing | 2025 |
| Lunar Bars Ltd | Hospitality | 2026 |
| Luta Services Limited | Transport & logistics | 2024 |
| Luvlash Supplies Limited | Wholesale & retail | 2024 |
| LUX Trading Limited | Wholesale & retail | 2020 |
| Luxe Remaps Teesside Ltd | Wholesale & retail | 2026 |
| Luxe SHE Hair Limited | Other services | 2022 |
| Luxeattire Ltd | Wholesale & retail | 2023 |
| Luxeforge Developments Ltd | Real estate | 2026 |
| Luxelibaas Ltd | Wholesale & retail | 2025 |
| Luxescent Cosmetics Ltd | Wholesale & retail | 2026 |
| Luxury & Executive Travel (NE) Ltd | Other services | 2021 |
| Luxury Cars Sale Ltd | Wholesale & retail | 2023 |
| Luxury Garden Rooms Online Ltd | Manufacturing | 2024 |
| Luxury Properties Teesside Ltd | Real estate | 2025 |
| Luxury Wheels 4U Limited | Transport & logistics | 2024 |
| Luxus Furniture Ltd | Wholesale & retail | 2025 |
| Luxyn Ltd | Wholesale & retail | 2025 |
| LV Skip Hire Ltd | Water & waste | 2024 |
| Lvlz Management Limited | Arts & recreation | 2023 |
| LW Body Repairs Ltd | Wholesale & retail | 2019 |
| LW Comms. Ltd | Information & communication | 2022 |
| LW Cost Management Ltd | Professional & scientific | 2019 |
| LW888 Ltd | Hospitality | 2024 |
| LWH Enterprises Ltd | Hospitality | 2025 |
| Lwilsonengineering Ltd | Construction | 2025 |
| LX Ventures Ltd | Wholesale & retail | 2025 |
| LXV Locum Ltd | Professional & scientific | 2022 |
| Lymatel Limited | Health & social care | 2019 |
| Lynas Engineers Limited | Professional & scientific | 2016 |
| Lynch Soft Play Limited | Other services | 2018 |
| Lyndhurst Gardens Management Company Limited | Administrative & support | 2025 |
| Lynx Investments Limited | Financial services | 2024 |
| Lysaba ENG Consult Ltd | Professional & scientific | 2024 |
| Lysmar Limited | Information & communication | 2026 |
| LYT Crafters Limited | Wholesale & retail | 2024 |
| Lyth & Unwin Veterinary Services Limited | Professional & scientific | 2021 |
| LZ the Label Ltd | Wholesale & retail | 2024 |
| LZ Wholesale Ltd | Wholesale & retail | 2024 |
| LZK Accommodation Ltd | Hospitality | 2026 |
| M & J Metals Recycling Limited | Wholesale & retail | 2023 |
| M & K Designs NE Ltd | Manufacturing | 2018 |
| M & M Garages Ltd | Wholesale & retail | 2008 |
| M & M Hibbert Ltd | Professional & scientific | 2024 |
| M & V Properties (NE) Limited | Construction | 2017 |