| J Alexander Property Ltd | Real estate | 2020 |
| J Atherton Limited | Wholesale & retail | 2003 |
| J B Plumbing Limited | Construction | 2004 |
| J Boardman Joinery Ltd | Construction | 2026 |
| J Brownlie TM Ltd | Construction | 2024 |
| J C Catering & Bar Supplies Limited | Wholesale & retail | 2004 |
| J C Powertools Ltd | Wholesale & retail | 2024 |
| J Crow Ltd | Construction | 2019 |
| J Cunliffe Limited | Wholesale & retail | 2006 |
| J Cunningham Consulting Ltd | Information & communication | 2016 |
| J D Landscaping Limited | Construction | 2003 |
| J E Thompson Plastering Contractors Limited | Construction | 2010 |
| J English Limited | Construction | 2020 |
| J Everard and Associates Ltd | Health & social care | 2023 |
| J Farrer Ltd | Professional & scientific | 2016 |
| J Foulds Ltd | Hospitality | 2024 |
| J G Commercial Ltd | Administrative & support | 2026 |
| J G Rubbish Removals Ltd | Water & waste | 2025 |
| J H Gawthorpe Limited | Wholesale & retail | 2021 |
| J J O'Grady Limited | Professional & scientific | 2006 |
| J JAX Technical Services Ltd | Construction | 2017 |
| J Lall Cars Ltd | Wholesale & retail | 2023 |
| J LEE Heating & Plumbing Ltd | Construction | 2022 |
| J LEE TM Ltd | Construction | 2024 |
| J M Dixon Property Limited | Real estate | 2017 |
| J Major Construction Ltd | Construction | 2026 |
| J P Site Fixings Ltd | Construction | 2015 |
| J P T Property Group Ltd | Real estate | 2025 |
| J S Builders Yorkshire Ltd | Construction | 2018 |
| J Sheridan Caravans Ltd | Wholesale & retail | 2026 |
| J T Alexander Construction Ltd | Construction | 2025 |
| J T Builders Ltd | Construction | 2012 |
| J Unit Construction Solutions Limited | Construction | 2017 |
| J W Installations Ltd | Construction | 2025 |
| J Waddington Limited | Construction | 2007 |
| J Wilkinson Limited | Hospitality | 2006 |
| J&A Properties and Investments Ltd | Real estate | 2026 |
| J&B Site Solutions Ltd | Construction | 2026 |
| J&E Properties and Investments Ltd | Real estate | 2021 |
| J&K Solutions Ltd | Construction | 2025 |
| J&P Canine Academy Ltd | Other services | 2024 |
| J&P Gyms Ltd | Arts & recreation | 2023 |
| J-Juniors Ltd | Mining & quarrying | 2024 |
| J. Reside Limited | | 1968 |
| J. T. Livesey Limited | Wholesale & retail | 2012 |
| J.A.Jackson Contractors (Leyland) Limited | Mining & quarrying | 2010 |
| J.A.Jackson Contractors(Preston)Limited | Mining & quarrying | 1967 |
| J.C.Lowes(Holdings)Limited | Real estate | 1934 |
| J.D Holden Ltd | Real estate | 2025 |
| J.D. Domestic Repairs Limited | Administrative & support | 2003 |
| J.E.T. Consulting Services Limited | Information & communication | 2006 |
| J.H. & a. Miller Limited | Construction | 1991 |
| J.J. Securities Limited | Administrative & support | 1990 |
| J.Orritt Upvc Ltd | Construction | 2025 |
| J.R Tuckey Holdings Ltd | Financial services | 2025 |
| J3C Building Consultants Ltd | Construction | 2025 |
| JAB Capital & Partners Limited | Financial services | 2018 |
| JAC Family Estates Limited | Hospitality | 2026 |
| Jack PR Retail Limited | Wholesale & retail | 2023 |
| Jackson Homes (Northwest) Limited | Construction | 2019 |
| Jackson Safety Ltd | Professional & scientific | 2025 |
| Jackson Skip & Recycling Limited | Water & waste | 2006 |
| Jackson's Coachworks Ltd | Wholesale & retail | 2022 |
| Jackson's Turbo Repairs Limited | Wholesale & retail | 2008 |
| Jackson.Thompson Ltd | Hospitality | 2024 |
| Jacksons Development Ltd | Real estate | 2021 |
| Jacksons Logistics Limited | Transport & logistics | 2025 |
| Jade Jewellers and Pawnbrokers Limited | Wholesale & retail | 2008 |
| Jade Village Blackpool Ltd | Hospitality | 2025 |
| Jade's POWER4BUSINESS Ltd | Professional & scientific | 2024 |
| Jaguar Computers Limited | Information & communication | 2019 |
| JAI Global Prime Ltd | Information & communication | 2024 |
| Jaidi Limited | Information & communication | 2026 |
| JAJ Investments Limited | Real estate | 2004 |
| Jakub Chilczuk Limited | Information & communication | 2017 |
| Jale Creative Ltd | Professional & scientific | 2024 |
| Jalil Unipessoal Ltd | Manufacturing | 2021 |
| JAM Family Properties Limited | Real estate | 2025 |
| JAM Physiotherapy Ltd | Health & social care | 2013 |
| JAM Roll Ltd | Professional & scientific | 2019 |
| James Benedict Electrical Limited | Construction | 2015 |
| James Brearley & Sons Limited | Financial services | 1999 |
| James Jeffrey Developments Ltd | Real estate | 2024 |
| James Jorge Joinery Ltd | Construction | 2025 |
| James Lewis Solutions Ltd | Wholesale & retail | 2020 |
| James MAC Limited | Arts & recreation | 2017 |
| James Scott Surveyors Ltd | Professional & scientific | 2022 |
| James Wood Electrical Services Ltd | Construction | 2021 |
| Jamma Holdings Limited | Professional & scientific | 2018 |
| Jamtech Engineering Ltd | Manufacturing | 2025 |
| JAN Weszka Limited | Manufacturing | 2014 |
| Janafarag Ltd | Wholesale & retail | 2016 |
| Jane Clarke Consultancy Ltd | Wholesale & retail | 2026 |
| Janemar Limited | Hospitality | 2023 |
| Janina-Daniela Lifestyle Studios Limited | Education | 2022 |
| Janrobinson Ltd | Information & communication | 2018 |
| Jans Kitchen Ltd | Hospitality | 2026 |
| Japalcosmetics Limited | Wholesale & retail | 2024 |
| Japareloaded Impact Global Initiative CIC | Administrative & support | 2026 |
| Jaroshan Ltd | Hospitality | 2023 |