| J Power Construction Ltd | Professional & scientific | 2019 |
| J Reid Rigging and Lifting Limited | Construction | 2012 |
| J S Cooper & Sons Limited | Construction | 2026 |
| J S D Security Limited | Transport & logistics | 2009 |
| J S Plastering and Building Ltd | Construction | 2023 |
| J Sayer Ltd | Health & social care | 2025 |
| J Smith Offshore Ltd | Manufacturing | 2023 |
| J Sole Safety Limited | Professional & scientific | 2018 |
| J Southern Electrical Services Ltd | Construction | 2023 |
| J Splice Ltd | Construction | 2019 |
| J Stephenson Limited | Hospitality | 2023 |
| J T Recycling & Aggregates Ltd | Water & waste | 2016 |
| J W Autos(Teesside) Ltd | Wholesale & retail | 2021 |
| J Walton Offshore Services Limited | Manufacturing | 2017 |
| J Watson Security Limited | Administrative & support | 2018 |
| J&H Interiors Ltd | Construction | 2018 |
| J&I Property Group Limited | Real estate | 2025 |
| J&J Electrical Solutions NE Limited | Construction | 2020 |
| J&J Oakwood Properties Ltd | Real estate | 2026 |
| J&M Cleaning Services Ltd | Administrative & support | 2024 |
| J&T Communications Limited | Construction | 2023 |
| J. Hewitt Crane Hire Limited | Construction | 1982 |
| J. M. Dixon Associates Limited | Professional & scientific | 1984 |
| J. Moran Limited | Wholesale & retail | 2002 |
| J.A Lochrane Ltd | Professional & scientific | 2026 |
| J.C Shopfitters Ltd | Real estate | 2019 |
| J.E.F Electrical Ltd | Construction | 2017 |
| J.E.M NE Limited | Construction | 2026 |
| J.H.W.I. Limited | Wholesale & retail | 1981 |
| J.L Traders Ltd | Wholesale & retail | 2024 |
| J.M. Construction (SW) Limited | Construction | 2019 |
| J.Walton Mechanical Ltd | Manufacturing | 2025 |
| J.Williamson(Warehousing)Limited | Construction | 1958 |
| JA Plastering and Property Maintenance Ltd | Construction | 2023 |
| Jaan Properties Ltd | Real estate | 2020 |
| JAB Roofing Contractors Ltd | Construction | 2020 |
| JAC Supervision Limited | Professional & scientific | 2017 |
| Jaceyb's Ltd | Professional & scientific | 2021 |
| Jachlosar Design Limited | Professional & scientific | 2008 |
| Jack MAC Services Ltd | Other services | 2017 |
| Jack&Rs Ltd | Construction | 2017 |
| Jackdaw Communications Limited | Professional & scientific | 2024 |
| Jacksons Commercial & Private Law LLP | | 2003 |
| Jacksons Company Secretarial Limited | Professional & scientific | 2018 |
| Jacksons Law Limited | Professional & scientific | 2004 |
| Jacksons Solicitors Limited | Professional & scientific | 2004 |
| JACL1 Ltd | Transport & logistics | 2026 |
| Jada Joinery and Home Improvements Ltd | Construction | 2022 |
| Jade Espin Limited | Wholesale & retail | 2025 |
| Jadis Recycling Holdings Limited | Professional & scientific | 2011 |
| Jamas Building Services Limited | Administrative & support | 2005 |
| Jambo Media Ltd | Professional & scientific | 2025 |
| Jameck Associates Ltd | Professional & scientific | 2021 |
| James Chappell Property Consultancy Limited | Real estate | 2016 |
| James Heslop Construction Limited | Construction | 2025 |
| Jammy JAK Properties Limited | Real estate | 2006 |
| Janarber Limited | Financial services | 2025 |
| Japoc Ltd | Health & social care | 2024 |
| Jaspers Eco Heat Limited | Construction | 2015 |
| Jatie's Coffee and Matcha Limited | Hospitality | 2026 |
| Jatt Army Construction Ltd | Real estate | 2024 |
| JAW Franchising Limited | Professional & scientific | 2018 |
| JAY Autos Teesside Limited | Wholesale & retail | 2025 |
| JAY Milen Group Limited | Real estate | 2007 |
| Jay&Jo Limited | Administrative & support | 2021 |
| Jaykor Limited | Professional & scientific | 2008 |
| JB & M Flooring Limited | Wholesale & retail | 2013 |
| JB BMS Locum Ltd | Health & social care | 2024 |
| JB Electrical Contractors (Teesside) Limited | Construction | 2022 |
| JB Investments NE Limited | Health & social care | 2026 |
| JB Lownds Property Ltd | Real estate | 2021 |
| JB Physio and Rehab Ltd | Health & social care | 2025 |
| JB Technical Services Ltd | Manufacturing | 2009 |
| JBC Payroll Limited | Professional & scientific | 2015 |
| JBEAU11 Ventures Ltd | Arts & recreation | 2025 |
| JBH Electrical Ltd | Construction | 2026 |
| JBV Construction Ltd | Construction | 2019 |
| JC Inspection Ltd | Professional & scientific | 2024 |
| JC Plant & Tool Hire Ltd | Administrative & support | 2025 |
| JCB Communications Ltd | Information & communication | 2022 |
| JCB NE Limited | Professional & scientific | 2011 |
| Jchs Electrical Ltd | Construction | 2022 |
| Jckc Hospitality Limited | Hospitality | 2011 |
| JCM Commercial Management Limited | Professional & scientific | 2019 |
| JCP Innovation UK Ltd | Manufacturing | 2022 |
| JCP Media Ltd | Manufacturing | 2025 |
| JCS Management Services Limited | Construction | 2025 |
| JD Training (Teesside) Ltd | Education | 2024 |
| JD Training Solutions Ltd | Education | 2005 |
| JDK Planning Solutions Limited | Professional & scientific | 2011 |
| Jdme Consulting Ltd | Construction | 2023 |
| JDW Ceramics Limited | Construction | 2014 |
| JE Associates Ltd | Professional & scientific | 2016 |
| Jeave 4 Limited | Extraterritorial | 2010 |
| Jecy Rubas Ltd | Administrative & support | 2019 |
| Jeff Rathbone Limited | Professional & scientific | 2017 |
| JEN & Jamie Ltd | Wholesale & retail | 2021 |
| Jenroy Limited | Wholesale & retail | 2025 |
| JER Property Maintenance and Facility Management Ltd | Administrative & support | 2019 |
| Jerk and RUM Street Food Ltd | Hospitality | 2023 |