| Kstar Tech (NE) Ltd | Real estate | 2017 |
| KT Pipeline Integrity Ltd | Professional & scientific | 2014 |
| KT Property (NE) Ltd | Real estate | 2026 |
| KTE Group Ltd | Real estate | 2024 |
| KTS Beauty Accountants Ltd | Professional & scientific | 2020 |
| KTS Method Ltd | Education | 2026 |
| Ktsbeauty Ltd | Information & communication | 2023 |
| KU Club Limited | Hospitality | 2017 |
| Kudilil Cura Limited | Administrative & support | 2014 |
| Kudos Housing Development and Management Ltd | Real estate | 2024 |
| Kudos Marketing & Advertising Ltd | Information & communication | 2020 |
| Kumar Trading Centre Ltd | Transport & logistics | 2023 |
| Kurd Fade Zone Ltd | Other services | 2025 |
| Kurdi Ltd | Other services | 2021 |
| Kurt's Kitchen Limited | Hospitality | 2025 |
| Kurts Korner Limited | Hospitality | 2025 |
| Kustomize Ltd | Wholesale & retail | 2022 |
| KW FF Limited | Professional & scientific | 2024 |
| L & D Leisure Limited | Real estate | 2013 |
| L & L Braines Limited | Transport & logistics | 2014 |
| L & R Home Improvements and Removals Ltd | Construction | 2025 |
| L & W R Properties Limited | Households | 2025 |
| L a COX Developments Ltd | Real estate | 2018 |
| L a Rose Housing Ltd | Real estate | 2025 |
| L a Wind Ltd. | Manufacturing | 2021 |
| L E Performing Arts Limited | Arts & recreation | 2018 |
| L J B Construction North East Limited | Construction | 2014 |
| L K Property Management and Maintenance Ltd | Households | 2021 |
| L&D Access Ltd | Construction | 2024 |
| L&G Metalwork Ltd | Manufacturing | 2024 |
| L&H Embroidery & Design Ltd | Manufacturing | 2024 |
| L&L Car Sales Ltd | Wholesale & retail | 2026 |
| L&Llettings Ltd | Real estate | 2025 |
| L&M Catering Limited | Hospitality | 2020 |
| L&R Care Home Podiatry UK Ltd | Health & social care | 2025 |
| L&R Groundworks and Paving Specialists Limited | Construction | 2025 |
| L&S Property Services North East Ltd | Administrative & support | 2019 |
| L.A.O Accounting Limited | Professional & scientific | 2023 |
| L.R.W. Whitburn Ltd | Manufacturing | 2025 |
| LA Beauté Elevée Ltd | Other services | 2025 |
| LAC Social Limited | Professional & scientific | 2022 |
| Laelle Holding Ltd | Information & communication | 2021 |
| Laidler International Limited | Professional & scientific | 1991 |
| Lakeside Association Ltd | Transport & logistics | 2016 |
| Lalitha Consulting Ltd | Health & social care | 2015 |
| Lamb Engineering Services Ltd | Professional & scientific | 2024 |
| Lambton House Ltd | Health & social care | 2012 |
| Lambton Street Youth & Community Hub | Arts & recreation | 2014 |
| Lamensa Property Ltd | Real estate | 2025 |
| Lamplight Education Limited | Education | 2023 |
| Lamproom Digital Ltd | Information & communication | 2025 |
| Lancaster Accountants Ltd | Professional & scientific | 2016 |
| Lancaster LUX Limited | Professional & scientific | 2017 |
| Land and Display Limited | Construction | 1989 |
| Land Digital Solutions Limited | Information & communication | 2015 |
| Landsun Ltd | Wholesale & retail | 2025 |
| Landthorpe Limited | Wholesale & retail | 2017 |
| Landtrader (UK & Ireland) Limited | Information & communication | 2016 |
| Langdon Hamblin Sales Consultancy Ltd | Professional & scientific | 2011 |
| Langikoki Limited | Health & social care | 2022 |
| Lanner Properties Ltd | Real estate | 2023 |
| Lansdownedeptford Ltd | Hospitality | 2026 |
| Lara Management Services Ltd | Financial services | 2026 |
| Lara's Kitchen Ltd | Hospitality | 2024 |
| Larisa Pizza Ltd | Hospitality | 2026 |
| Larne Kitchens Ltd | Construction | 2021 |
| Lasgidi Restaurant and Lounge Ltd | Hospitality | 2025 |
| Lashbrooke Limited | Construction | 2018 |
| Lashes by Deonne Limited | Other services | 2024 |
| Lashluxe Limited | Other services | 2025 |
| Latimers Seafood Limited | Wholesale & retail | 2015 |
| Laundry Monster Ltd | Other services | 2023 |
| Laura Amundsen Emerald Aesthetics Limited | Health & social care | 2020 |
| Laurelgreen Energyfarm Limited | Energy | 2024 |
| Laurenl Ltd | Wholesale & retail | 2023 |
| Lavan Tech Limited | Information & communication | 2017 |
| Lavasan Ltd | Administrative & support | 2019 |
| Lawnav Ltd | Other services | 2009 |
| Laws Dispense Services Limited | Professional & scientific | 2010 |
| Lawson Studios Limited | Professional & scientific | 2018 |
| LAY Cousins Properties Limited | Real estate | 2020 |
| Laybourne Roberts Limited | Real estate | 2020 |
| Lazi Construction Ltd | Construction | 2024 |
| Lazy Living Limited | Professional & scientific | 2006 |
| Lazy Lizard Brewing Company Limited | Hospitality | 2020 |
| Lazy Lizard Leisure Ltd | Hospitality | 2025 |
| Lazy Lounger Ltd | Manufacturing | 2026 |
| Lazylife Ltd | Professional & scientific | 2011 |
| LBB Leisure Trading Ltd | Hospitality | 2026 |
| LBH Property North East Ltd | Real estate | 2019 |
| LBM Wind Ltd | Manufacturing | 2024 |
| Lbwind Ltd | Construction | 2024 |
| LCO Fire and Security Limited | Other services | 2025 |
| LCV Technical Services Limited | Other services | 2018 |
| LD Electrical NE Limited | Construction | 2026 |
| LD Properties NE Ltd | Real estate | 2026 |
| LD Property Letting Ltd | Households | 2026 |
| Lead Pathways Ltd | Education | 2023 |
| Leadsinthenorth Limited | Professional & scientific | 2019 |
| Leaflet Drop UK Ltd | Professional & scientific | 2012 |