| Jdps Accounts Limited | Professional & scientific | 2025 |
| JDR Medical Limited | Health & social care | 2015 |
| Jeaves Ltd | Other services | 2020 |
| JEH Construction Project Management Ltd | Construction | 2020 |
| Jellybean Play Ltd | Hospitality | 2026 |
| JEM Business Ventures Limited | Administrative & support | 2015 |
| Jenson Graham Racing Ltd | Arts & recreation | 2023 |
| Jewett Holding Limited | Real estate | 2025 |
| JF Reinforcement (Durham) Ltd | Construction | 2018 |
| JG Holdings (NE) Ltd | Financial services | 2024 |
| JG Safety Ltd | Professional & scientific | 2025 |
| JGO Consultancy Limited | Construction | 2015 |
| JGR Roofing & Cladding Ltd | Construction | 2016 |
| JH Construction (NE) Ltd | Construction | 2017 |
| JH Partners Consulting Engineers Limited | Administrative & support | 2004 |
| Jharker Holdings Limited | Real estate | 2023 |
| JHJ Consulting Ltd | Construction | 2019 |
| Jhrichardsonengineering Ltd | Professional & scientific | 2021 |
| JIA Ventures Ltd | Financial services | 2026 |
| Jive Property Ltd | Real estate | 2018 |
| JJ Industries UK Ltd | Manufacturing | 2021 |
| JJ Well Control Ltd | Professional & scientific | 2024 |
| JJS Management Ltd | Hospitality | 2016 |
| Jlcw Maintenance Ltd | Construction | 2023 |
| JLG Properties Durham Ltd | Real estate | 2025 |
| JLK Property Ltd | Real estate | 2022 |
| JLR Contracts Ltd | Construction | 2019 |
| Jlrr Plotworks Ltd | Construction | 2025 |
| JM Campers Ltd | Manufacturing | 2026 |
| JM Solutions (North East) Ltd | Construction | 2022 |
| JMA Commercial Limited | Professional & scientific | 2018 |
| JMC Groundworks North East Ltd | Construction | 2023 |
| JMF Compliance Limited | Professional & scientific | 2015 |
| JN Technology Limited | Information & communication | 2026 |
| JNB Pubs Limited | Hospitality | 2026 |
| JNR Sherburn Taxis Limited | Transport & logistics | 2018 |
| Joat Property Services Ltd | Construction | 2023 |
| Joat Tech Ltd | Information & communication | 2026 |
| Jobes Lettings Limited | Real estate | 2025 |
| JOE Byrne Electrics Ltd | Construction | 2020 |
| JOE Wills Ltd | Information & communication | 2010 |
| John Cullerton & Sons Limited | Construction | 2002 |
| John Eliot (Footwear) Limited | Wholesale & retail | 1978 |
| John Hanks Limited | Professional & scientific | 1999 |
| John Hedley Limited | Information & communication | 2003 |
| John Kilner Transport Ltd | Transport & logistics | 2015 |
| John Simpson Civils Limited | Construction | 2012 |
| John Willetts (Developments) Limited | Real estate | 2003 |
| Johns Timber Limited | Manufacturing | 2018 |
| Johnsons Groundworks NE Limited | Construction | 2026 |
| Jolan Piccadilly Limited | Real estate | 2009 |
| JON Daniels Properties Limited | Real estate | 2024 |
| Jonathan Quinn Construction Ltd | Construction | 2018 |
| Jones Boyd (Durham) Limited | Professional & scientific | 2014 |
| Jones Truck & Trailer Services Ltd | Manufacturing | 2011 |
| Jonnycooksfood Ltd | Hospitality | 2023 |
| Joose Energy Ltd | Professional & scientific | 2020 |
| Jorb Brickworks Ltd | Construction | 2026 |
| Jordan's Groundworks Ltd | Construction | 2021 |
| Josh Daniels Limited | Arts & recreation | 2011 |
| JP Health LLP | | 2017 |
| JP Joinery & Timber Frame Ltd | Construction | 2026 |
| JPS Systems N.E. Limited | Manufacturing | 2005 |
| JPT Hospitality Company Limited | Hospitality | 2026 |
| JPT Repairs Limited | Manufacturing | 2023 |
| JR Aerial Photography Ltd | Professional & scientific | 2021 |
| JR Car Dealers Ltd | Wholesale & retail | 2018 |
| JR Plotworks Ltd | Construction | 2014 |
| Jrcs Commercial Services Ltd | Professional & scientific | 2023 |
| JRV Residential Surveyors and Valuers Ltd | Professional & scientific | 2026 |
| JS Bell Ltd | Financial services | 2021 |
| JS Bell Properties Ltd | Administrative & support | 2021 |
| JS Computers North East Limited | Wholesale & retail | 2014 |
| JS Consultancy (NE) Limited | Professional & scientific | 2021 |
| JS Fire Consultancy Ltd | Public administration | 2023 |
| JS Gadgets Limited | Wholesale & retail | 2021 |
| JS Gill Property Limited | Real estate | 2023 |
| JSC Construction NE Ltd | Construction | 2025 |
| Jsck Property Ltd | Real estate | 2026 |
| Jsgrigg Ltd | Transport & logistics | 2026 |
| JSR Business Solutions Limited | Other services | 2022 |
| JST Trading Ltd | Wholesale & retail | 2023 |
| JT Bailey LLP | | 2023 |
| Judge Brands Ltd | Wholesale & retail | 2021 |
| Judy Roberts Limited | Other services | 2017 |
| Julian George Design Ltd | Professional & scientific | 2020 |
| Jungle Drum Connections Limited | Other services | 2008 |
| Juniper Care and Support Ltd | Health & social care | 2022 |
| Jury Engineering Ltd | Professional & scientific | 2022 |
| Just for Tonight Events Ltd | Other services | 2020 |
| Just Guard Limited | Information & communication | 2026 |
| Just OUT Marketing Limited | Professional & scientific | 2010 |
| Just Perfect (Outlet) Ltd | Wholesale & retail | 2017 |
| JW Drywall Ltd | Construction | 2025 |
| JW Property Solutions Ltd | Construction | 2014 |
| JWA Holdings NE Ltd | Financial services | 2025 |
| Jwak Civils and Plant Hire Ltd | Construction | 2018 |
| JWS Joinery and Property Maintenance Ltd | Construction | 2024 |
| JWS Motors Ltd | Wholesale & retail | 2017 |
| K & a Engineering Services Limited | Mining & quarrying | 2016 |