| Kingsgate Marketing Ltd | Professional & scientific | 2023 |
| Kinosport Ltd | Information & communication | 2022 |
| Kira's Kebab House Ltd | Hospitality | 2024 |
| Kirsha Ltd | Real estate | 2023 |
| Kiss My Crafts Ltd | Wholesale & retail | 2025 |
| KJ Lynch Consulting Ltd | Administrative & support | 2012 |
| KJ86 Ltd | Wholesale & retail | 2022 |
| Klsd C.I.C. | Arts & recreation | 2015 |
| Klsd Community Ventures C.I.C. | Hospitality | 2020 |
| KMS Rigging and Lifting Limited | Professional & scientific | 2025 |
| KNF Renewables Ltd | Construction | 2018 |
| Knowing Your Numbers Ltd | Information & communication | 2019 |
| Knowledge Technical Consulting Ltd | Professional & scientific | 2014 |
| Ko.Ds Surfacing Ltd | Construction | 2021 |
| Kommercial Sense 2006 Limited | Wholesale & retail | 2006 |
| Kooner Singh Ltd | Hospitality | 2018 |
| KR Cable Jointing Ltd | Construction | 2018 |
| KR Lidiard Logistics Ltd | Transport & logistics | 2025 |
| Kris K Transport Limited | Transport & logistics | 2025 |
| Krish’S Flowers Limited | Wholesale & retail | 2022 |
| KRM Group Ltd | Hospitality | 2024 |
| Kroben IT Solutions & Consultancy Limited | Information & communication | 2014 |
| KS Custom Tech Ltd | Information & communication | 2021 |
| KS Dance Warehouse Ltd | Education | 2025 |
| KSC Offshore Services Ltd | Manufacturing | 2026 |
| KSW Transport Limited | Transport & logistics | 2025 |
| KT Inspection Ltd | Professional & scientific | 2026 |
| KTM Rigging and Lifting Ltd | Construction | 2026 |
| KTW Access Specialist Ltd | Construction | 2026 |
| Kurdistan Shawarma (NE) Ltd | Hospitality | 2025 |
| Kutho Ltd | Real estate | 2025 |
| L & B Property Developments Limited | Construction | 2019 |
| L & D Windows Ltd | Construction | 2017 |
| L & G Bricklaying Services Ltd | Administrative & support | 2012 |
| L & G Build Ltd | Construction | 2024 |
| L & G Construction Services Limited | Real estate | 2019 |
| L & G Residential Ltd | Real estate | 2021 |
| L & R Industrial Services Limited | Wholesale & retail | 2007 |
| L B Y (NE) Ltd | Hospitality | 2025 |
| L Beeston Ltd | Manufacturing | 2025 |
| L E Jointing Ltd | Construction | 2017 |
| L K Health and Safety Ltd | Professional & scientific | 2024 |
| L Lectrical Limited | Construction | 2023 |
| L M N Site Services Limited | Administrative & support | 2017 |
| L P Mechanical Ltd | Professional & scientific | 2022 |
| L S Global Foods Ltd | Wholesale & retail | 2021 |
| L S P J Limited | Financial services | 2018 |
| L W Plumbing Limited | Construction | 2016 |
| L Y Z 88 Ltd | Hospitality | 2022 |
| L&G Companies Ltd | Financial services | 2025 |
| L&L Bathrooms Limited | Construction | 2026 |
| L&L Kitchen and Bathrooms Ltd | Wholesale & retail | 2016 |
| L&L Properties NE Limited | Real estate | 2024 |
| L&R Digital Marketing Consultancy Ltd | Professional & scientific | 2025 |
| L&S Hartlepool Limited | Professional & scientific | 2014 |
| L. & P. Motors Limited | Real estate | 1948 |
| L.Kanaan Limited | Wholesale & retail | 2025 |
| LA Nuova Hartlepool Limited | Hospitality | 2024 |
| LAB Vault Ltd | Real estate | 2025 |
| Labshop Limited | Professional & scientific | 2006 |
| LAC Rigging and Lifting Limited | Other services | 2017 |
| Lachli Limited | Wholesale & retail | 2026 |
| Ladysmith Properties Ltd | Real estate | 2020 |
| Laila Express Wash Ltd | Administrative & support | 2026 |
| LAJ Industrial Ltd | Administrative & support | 2024 |
| Lamburn Developments Ltd | Construction | 2022 |
| Landcraft NE Ltd | Construction | 2019 |
| Lannon Engineering Ltd | Manufacturing | 2019 |
| Larb Property Ltd | Real estate | 2025 |
| LAS Civils Ltd | Construction | 2021 |
| Lasercraft Hartlepool Ltd | Other services | 2025 |
| Last City Brewing Ltd | Manufacturing | 2023 |
| Laststeps Solutions Limited | Other services | 2025 |
| LAU Lashes Ltd | Wholesale & retail | 2023 |
| Lauras Aesthetics Limited | Other services | 2024 |
| Laverick Hall Farm Limited | Real estate | 2016 |
| Lavericks HV Services Ltd | Construction | 2025 |
| Lawnhopper (NE) Limited | Other services | 2017 |
| LB Audiology Services Ltd | Health & social care | 2020 |
| LB Signature Plates Ltd | Wholesale & retail | 2026 |
| LB Web Consultancy Ltd | Administrative & support | 2018 |
| LC Fabrication and Welding Ltd | Construction | 2025 |
| LC Joyson Ltd | Manufacturing | 2025 |
| LC MAY Services Limited | Professional & scientific | 2025 |
| Lcert Ltd | Construction | 2025 |
| Lctk Mechanical Services Ltd | Professional & scientific | 2026 |
| LD Electrical Services Limited | Construction | 2019 |
| LDC Mechanical Services Ltd | Manufacturing | 2022 |
| LDC Site Services Ltd | Professional & scientific | 2021 |
| Ldem Industrial Services Limited | Construction | 2026 |
| Ldjj Ltd | Hospitality | 2019 |
| LE Basil Pizza Limited | Hospitality | 2024 |
| Leabba Services Limited | Professional & scientific | 2018 |
| Leader Group Investments Limited | Financial services | 2014 |
| Leader Group Property Limited | Real estate | 2025 |
| Leader Online (Holdings) Limited | Financial services | 2014 |
| Leader Property Number 2 Limited | Real estate | 2017 |
| Leadwise Leisure Group Ltd | Professional & scientific | 2022 |
| Leaning Tower Property Ltd | Real estate | 2016 |
| Leap Driver Training Ltd | Education | 2025 |