| J M Electrical & Property Ltd | Construction | 2022 |
| J Mason Construction Ltd | Construction | 2023 |
| J Mcblain Financial Planning Limited | Financial services | 2017 |
| J Millican Limited | Administrative & support | 2016 |
| J Molina Private Limited | Health & social care | 2016 |
| J N S Store Ltd | Wholesale & retail | 2019 |
| J P Cooke and Sons Limited | Professional & scientific | 2016 |
| J P Dencare Limited | Administrative & support | 2016 |
| J P Walton Limited | Financial services | 2013 |
| J Page Consulting Limited | Information & communication | 2015 |
| J Plunkett Gardening Services Limited | Administrative & support | 2023 |
| J R Technical Services UK Limited | Wholesale & retail | 2007 |
| J Ramsay Roofing Ltd | Construction | 2014 |
| J Renton Groundworks Limited | Construction | 2002 |
| J Rowley Marketing Limited | Professional & scientific | 2012 |
| J S Constructions (NCL) Ltd | Construction | 2025 |
| J S Welch NE Ltd | Construction | 2022 |
| J Sanderson Electrical Ltd | Construction | 2013 |
| J Shield IT Services Limited | Information & communication | 2014 |
| J T a Limited | Professional & scientific | 2006 |
| J T Omalley Limited | Health & social care | 2023 |
| J W Pillinger Limited | Professional & scientific | 2012 |
| J W Utilities Limited | Construction | 2010 |
| J Watson Builders Limited | Construction | 2012 |
| J Wills Services Ltd | Professional & scientific | 2025 |
| J Wood Solutions Limited | Professional & scientific | 2012 |
| J&D Patel Ltd | Wholesale & retail | 2022 |
| J&Fr Coffee and Dessert Ltd | Manufacturing | 2024 |
| J&G Cleaning Ltd | Administrative & support | 2022 |
| J&G Welding Ltd | Manufacturing | 2019 |
| J&J Plumber’S Limited | Construction | 2025 |
| J&J's FIX and Flip Ltd | Real estate | 2025 |
| J&M Travel NE Ltd | Transport & logistics | 2026 |
| J&S Journey of Success Ltd | Wholesale & retail | 2024 |
| J&Sonscleaningservices Ltd. | Administrative & support | 2026 |
| J'Aime Sports Therapy Ltd | Arts & recreation | 2017 |
| J-Seva Limited | Hospitality | 2013 |
| J. & G. Inns Limited | Hospitality | 2002 |
| J. & J. Whittaker (Chemist) Limited | Wholesale & retail | 1989 |
| J. & W. Lowry (Bedlington) Limited | Construction | 2019 |
| J. & W. Lowry Limited | Construction | 1964 |
| J. a. Ostell Properties Ltd | Real estate | 2024 |
| J. Alexander Properties Ltd | Real estate | 2019 |
| J. Dinning (Jarrow) Limited | Wholesale & retail | 2012 |
| J. Ednieds Ltd | Information & communication | 2024 |
| J. M. D. Developments Limited | Real estate | 1978 |
| J. T. B. (Chapel Farm) Estates Limited | Professional & scientific | 1960 |
| J. V. Management Projects Limited | Professional & scientific | 2016 |
| J.& H.B.Ibbitson(Sunderland)Limited | Wholesale & retail | 1956 |
| J.A Ostell Electrical Limited | Construction | 2015 |
| J.A. Property Management Ltd | Real estate | 2021 |
| J.A.S Paving Ltd | Construction | 2019 |
| J.Bradburn & Company (Holdings) Limited | Professional & scientific | 2008 |
| J.C. Gillie & Partners Limited | Health & social care | 1965 |
| J.D. Storey & Co. LLP | | 2009 |
| J.G. Rigging and Lifting Ltd | Professional & scientific | 2023 |
| J.H.Cowper Investments Limited | Other services | 1964 |
| J.J.D.J. Holding Ltd | Construction | 2020 |
| J.Knapp & Sons Limited | Real estate | 1948 |
| J.M.& W.Darling Limited | Wholesale & retail | 1930 |
| J.Mccheyne Construction Limited | Real estate | 1970 |
| J.N. Fancy Goods Ltd | Wholesale & retail | 2020 |
| J.O.& R.H.Baird Limited | Manufacturing | 1938 |
| J.R. Textiles London (1989) Limited | Professional & scientific | 1966 |
| J.R.Birkett & Sons,Limited | Manufacturing | 1938 |
| J.T. Cuthbert Limited | Construction | 2012 |
| J.T. Dove Pensions Trust Limited | Financial services | 1954 |
| J.T. Straughan & SON Limited | Extraterritorial | 2012 |
| J.T.B.Estates Limited | Professional & scientific | 1960 |
| J.T.Dove,Limited | Wholesale & retail | 1905 |
| J.W. Plastering Limited | Construction | 2006 |
| J2 Property Services Ltd | Administrative & support | 2019 |
| J2RCARPETS Limited | Wholesale & retail | 2019 |
| J3 Properties Limited | Real estate | 2014 |
| J4C KO Ltd | Hospitality | 2018 |
| JA Designs & Joinery Ltd | Manufacturing | 2023 |
| JA Software Solutions Limited | Information & communication | 2020 |
| Jaac Limited | Real estate | 2022 |
| Jaas E-Commerce Ltd | Wholesale & retail | 2025 |
| JABICADOS5 Broad Concepts Limited | Wholesale & retail | 2023 |
| JAC Media Online Ltd | Professional & scientific | 2018 |
| Jac's Taxis Ltd | Transport & logistics | 2025 |
| Jaccountancy (UK) Ltd | Professional & scientific | 2019 |
| Jaccountancy Holdings Ltd | Financial services | 2024 |
| Jaccountancy TTR Ltd | Professional & scientific | 2025 |
| Jace Cosmetics Limited | Manufacturing | 2019 |
| Jack and Willow Homes Ltd | Real estate | 2025 |
| Jack Bagnall Properties Ltd | Real estate | 2021 |
| Jack Brent Ltd | Education | 2025 |
| Jack Ford Limited | Wholesale & retail | 1977 |
| Jack Ford Motors Limited | Wholesale & retail | 2005 |
| Jack Harrison Ltd | Real estate | 2016 |
| Jack in the BAG Ltd | Wholesale & retail | 2019 |
| Jack Mutton Limited | Manufacturing | 2018 |
| Jack Oddie Voiceover Limited | Information & communication | 2018 |
| Jack Rabbit Ventures Limited | Information & communication | 2013 |
| Jack Thai NE Ltd | Hospitality | 2025 |
| Jack Trattles Electrical Limited | Energy | 2016 |
| Jack Wilkinson Limited | Real estate | 2017 |
| Jackdaw Media Limited | Information & communication | 2015 |