| Intelligent Eco Limited | Professional & scientific | 2025 |
| Intelyx Ltd | Administrative & support | 2026 |
| Inter Contractor Ltd | Other services | 2021 |
| International Inspection Services (IIS) Ltd | Construction | 2024 |
| Into the Woods Family Cafe Limited | Hospitality | 2024 |
| Invest With ME Ltd | Real estate | 2025 |
| IO Energy Solutions Ltd | Construction | 2023 |
| Ironclad Security Services Ltd | Administrative & support | 2024 |
| Irongate Locksmiths Ltd | Other services | 2023 |
| Ironside Access Limited | Construction | 2021 |
| Irtizon Ltd | Wholesale & retail | 2025 |
| Isofire Ltd | Public administration | 2023 |
| IT Emissary Limited | Information & communication | 2020 |
| Itzbugginiz Limited | Arts & recreation | 2017 |
| Ivape IV Limited | Wholesale & retail | 2022 |
| Ivility Ltd | Professional & scientific | 2025 |
| IVW Limited | Wholesale & retail | 2024 |
| J & a North East Limited | Real estate | 2022 |
| J a Marshall Ltd | Information & communication | 2020 |
| J B Welding Ltd | Manufacturing | 2010 |
| J Barbour and Sons (Manufacturing) Limited | Manufacturing | 2009 |
| J Bella Ltd | Arts & recreation | 2024 |
| J C Electrical & Security Services Ltd | Construction | 2012 |
| J C Maintenance Services Ltd | Administrative & support | 2010 |
| J Hogg Solutions Ltd | Construction | 2022 |
| J J Murray Ltd | Construction | 2016 |
| J MC Professional Ltd | Construction | 2022 |
| J Shipley & Co Renewables Ltd | Construction | 2023 |
| J Step V Limited | Professional & scientific | 2018 |
| J Ullah Rigging Limited | Construction | 2025 |
| J W S Wind Power Repairs Ltd | Manufacturing | 2018 |
| J&C Leisure Limited | Hospitality | 2025 |
| J'S Tool Hire Limited | Wholesale & retail | 2022 |
| J.A.B NE Limited | Administrative & support | 2017 |
| J.W. Signature Homes Ltd | Real estate | 2025 |
| J2 Holdings Limited | Administrative & support | 2017 |
| J2 Research Limited | Administrative & support | 2004 |
| Jabero Engineering Ltd | Professional & scientific | 2024 |
| Jacks Yard Ltd | Hospitality | 2020 |
| Jafn Services Limited | Administrative & support | 2026 |
| Jahoggarth Ltd | Wholesale & retail | 2023 |
| Jaid Holdings Limited | Financial services | 2020 |
| Jam's Services Ltd | Manufacturing | 2025 |
| James H Wood Engineering Ltd | Manufacturing | 2021 |
| James LEE Lawrenson Limited | Extraterritorial | 2025 |
| Jamieson Quality Compliance (JQC) Ltd | Professional & scientific | 2025 |
| Janson Units Ltd | Construction | 2022 |
| Japrabani Limited | Real estate | 2025 |
| Jarrow Gardening Services Limited | Administrative & support | 2023 |
| Jary Constructions Limited | Construction | 2025 |
| Jason's Letting Limited | Real estate | 2023 |
| Javela Investments Ltd | Real estate | 2025 |
| Jayden Brian Hall Ltd | Extraterritorial | 2021 |
| JB Height Solutions Ltd | Professional & scientific | 2017 |
| JB Industrial Ltd | Construction | 2026 |
| JB Stores Ltd | Wholesale & retail | 2021 |
| JC Quay Ltd | Construction | 2012 |
| Jc's Convenience Store Limited | Wholesale & retail | 2025 |
| JCC Property Management Ltd | Real estate | 2025 |
| JCM Accountancy Limited | Professional & scientific | 2025 |
| JDM Property Solutions Ltd | Real estate | 2020 |
| Jean Medical Limited | Health & social care | 2019 |
| JEM Audio Ltd | Arts & recreation | 2026 |
| Jensen Construction Limited | Construction | 1999 |
| Jeremiah Hunter Ltd | Hospitality | 2024 |
| Jeremiah Plumbing Services Ltd | Construction | 2025 |
| Jesmin Property Ltd | Households | 2025 |
| Jesterpubco Limited | Hospitality | 2025 |
| Jewellery World London Ltd | Wholesale & retail | 2024 |
| Jewick Corporation Ltd | Wholesale & retail | 2026 |
| JH Wind Renewables Ltd | Construction | 2025 |
| JHA Autos Limited | Wholesale & retail | 2020 |
| Jhannard Driving Ltd | Transport & logistics | 2017 |
| Jimlititujumi Online Ltd | Wholesale & retail | 2023 |
| JJ Leisure NE Ltd | Hospitality | 2022 |
| JJ Properties NE Ltd | Real estate | 2025 |
| JJC NE Ltd | Construction | 2025 |
| JJH Heating Services Ltd | Construction | 2025 |
| JJM Facilities and Maintenance Limited | Construction | 2026 |
| JKW Technical Services Ltd | Professional & scientific | 2024 |
| JLH Electrics Limited | Construction | 2020 |
| JLL Project Management Ltd | Construction | 2025 |
| JLR Motors & Transportation Services Ltd | Wholesale & retail | 2026 |
| JLR Motors Ltd | Wholesale & retail | 2025 |
| JLR Plumbing and Heating Ltd | Construction | 2025 |
| JMC Power Solutions Ltd | Construction | 2024 |
| JMC Wind Ltd | Construction | 2024 |
| JMK Engineering Services Limited | Transport & logistics | 2018 |
| JMS Turbine Solutions Ltd | Professional & scientific | 2025 |
| Jnrvalets Ltd | Wholesale & retail | 2022 |
| JO Flooring Ltd | Construction | 2026 |
| JO Steel Fabricators Ltd | Manufacturing | 2025 |
| Joanna Tuck Limited | Extraterritorial | 2021 |
| Jockey Holdings Limited | Hospitality | 2019 |
| John Constantine Transport Limited | Transport & logistics | 2001 |
| John Duncan NE Ltd | Construction | 2011 |
| Joint Heaven Properties Ltd | Real estate | 2025 |
| Jonathan West Electrical Services Limited | Construction | 2014 |
| Jonortheastbuilders Limited | Construction | 2025 |
| Jordan Rose Ltd | Mining & quarrying | 2012 |