| Jj's Sweet Surprise Ltd | Wholesale & retail | 2021 |
| Jjane Medical Services Ltd | Health & social care | 2012 |
| Jjgv Limited | Hospitality | 2013 |
| Jjknn Holdings Limited | Wholesale & retail | 2019 |
| JJP Consulting Ltd | Professional & scientific | 2023 |
| JJP Interiors Ltd | Construction | 2018 |
| JJW Properties and Investments Ltd | Real estate | 2020 |
| JJW Roofing and Building Ltd | Construction | 2025 |
| JKM Couriers Ltd | Transport & logistics | 2026 |
| JKO Bars Ltd | Wholesale & retail | 2025 |
| JL Plasterers NE Ltd | Construction | 2021 |
| JLA Accounting Limited | Professional & scientific | 2013 |
| JLA Consultancy Ltd | Professional & scientific | 2022 |
| Jlah Limited | Financial services | 2019 |
| JLR Roofing & Cladding Services Limited | Construction | 2018 |
| JLR Tiling Ltd | Construction | 2021 |
| JM Automotive North East Limited | Wholesale & retail | 2023 |
| JM Landscaping NE Ltd | Administrative & support | 2022 |
| JM Overfield & SON Limited | Information & communication | 2010 |
| JMA PM Solutions Ltd | Professional & scientific | 2017 |
| Jmaxx Events Ltd | Arts & recreation | 2025 |
| JMD Associates (UK) Ltd | | 2014 |
| JMF Lettings Ltd | Real estate | 2022 |
| JNB Vehicle Recycling Ltd | Water & waste | 2018 |
| JOB and Tash Ltd | Health & social care | 2020 |
| JOB Ready Recruitment Ltd | Administrative & support | 2023 |
| Jodie Stott Limited | Other services | 2024 |
| JOE Cars D Ltd | Wholesale & retail | 2023 |
| JOE Cars N Ltd | Wholesale & retail | 2026 |
| John Dickinson Transport Limited | Transport & logistics | 2006 |
| John Flinn Physiotherapy Ltd | Health & social care | 2018 |
| John Kehinde Logistics Ltd | Transport & logistics | 2025 |
| John Ryan Building Services Limited | Construction | 2010 |
| John Simons Consulting Ltd | Professional & scientific | 2013 |
| John Wytcherley & SON Limited | Construction | 2003 |
| John's Homes Limited | Real estate | 2021 |
| Johnson Procurement Solutions Limited | Administrative & support | 2016 |
| Johnsony Limited | Wholesale & retail | 2025 |
| Join the Dots Sales Limited | Professional & scientific | 2019 |
| Joint Vision Direct Solution Limited | Wholesale & retail | 2025 |
| Joinus Hotels Limited | Hospitality | 2023 |
| Jolley & Co Limited | Real estate | 2016 |
| Jolley Flip Ltd | Real estate | 2024 |
| Jones and Matthews Consultancy Limited | Professional & scientific | 2014 |
| Jonny Smith Surveying Services Ltd | Construction | 2015 |
| Jordan Wingfield Construction Ltd | Construction | 2023 |
| Joseph Hughes Investments Unlimited | Financial services | 2020 |
| Joseph North Property Ltd | Real estate | 2024 |
| Joseph Thomas Catering Consultants Limited | Hospitality | 2021 |
| Josh Wooff Bespoke Limited | Construction | 2022 |
| Joshua's Dream Limited | Wholesale & retail | 2009 |
| Jossiah Homecare Limited | Health & social care | 2023 |
| Joy Ace Trading Ltd | Wholesale & retail | 2026 |
| Joyb Healthcare Limited | Health & social care | 2014 |
| JP Allied Services Ltd | Health & social care | 2019 |
| JP Classic Cars Ltd | Manufacturing | 2026 |
| JPA Scenery Services Limited | Information & communication | 2017 |
| JPB Engineering Consultants Ltd | Professional & scientific | 2014 |
| JPE Leisure Ltd | Hospitality | 2020 |
| JPG Training Ltd | Education | 2019 |
| Jpuk Holdings Ltd | Financial services | 2020 |
| JR RE Ltd | Manufacturing | 2025 |
| JRW Property Portfolio and Investments Limited | Real estate | 2024 |
| JRW Rigging Limited | Construction | 2019 |
| JS Engineering UK Ltd | Manufacturing | 2007 |
| JSA Rope Access Ltd | Construction | 2019 |
| JSB Subsea Engineering Ltd | Professional & scientific | 2017 |
| JSF Tools Limited | Wholesale & retail | 2025 |
| Jsleadsai Ltd | Professional & scientific | 2025 |
| JSP Hauliers Ltd | Transport & logistics | 2010 |
| JSW Homes Ltd | Real estate | 2026 |
| JSW Motors Ltd | Wholesale & retail | 2024 |
| JT Online Ltd | Wholesale & retail | 2021 |
| JT Roofing & Cladding Limited | Construction | 2014 |
| JT Transport (Darlington) Ltd | Transport & logistics | 2016 |
| JTA Couriers Ltd | Transport & logistics | 2015 |
| JTA Fires & Stoves Limited | Wholesale & retail | 2018 |
| JTA Fires Stoves and Heating Limited | Construction | 2020 |
| JTR Joinery North East Ltd | Construction | 2025 |
| Jtsv Holdings Limited | Real estate | 2025 |
| Juliette LEE Ltd | Professional & scientific | 2006 |
| Jump Capital Ltd | Financial services | 2020 |
| Junesounds Limited | Information & communication | 2021 |
| Juno Wedding Films Ltd | Professional & scientific | 2024 |
| Jupiter Growth | Financial services | 2024 |
| Jushy Ventures Limited | Hospitality | 2024 |
| Just Airsoft Ltd | Wholesale & retail | 2018 |
| Just Another Turn Ltd | Information & communication | 2014 |
| Just Health & Fitness Limited | Arts & recreation | 2018 |
| Just Paintball Limited | Wholesale & retail | 2010 |
| Just Think Communications Limited | Professional & scientific | 2006 |
| JUST2DEVS Limited | Information & communication | 2021 |
| Justage Limited | Financial services | 1994 |
| Justdents Darlington Limited | Wholesale & retail | 2019 |
| Juvent Limited | Health & social care | 2018 |
| JW and Sons Property Buyers Ltd | Construction | 2025 |
| JW Tools Nationwide Ltd | Wholesale & retail | 2017 |
| Jwcsupplies Limited | Wholesale & retail | 2024 |
| K & H Family Stores Ltd | Wholesale & retail | 2014 |
| K Estates (Advanced) Limited | Real estate | 2019 |