| Jennifer J Taylor Ltd | Health & social care | 2022 |
| Jennings & SON Limited | Extraterritorial | 2021 |
| Jerome Court RTM Company Limited | Households | 2018 |
| Jerry Decor Limited | Other services | 2020 |
| Jescu UK Ltd | Wholesale & retail | 2021 |
| Jessmee Ltd | Hospitality | 2025 |
| JET Fencing Limited | Manufacturing | 2012 |
| JET Preservation Ltd | Construction | 2004 |
| JET Property Investments Limited | Real estate | 2003 |
| JET Property Ltd | Real estate | 2005 |
| Jetlob Ltd | Real estate | 2026 |
| JETS2 Props Ltd | Administrative & support | 2025 |
| JF Digital Ltd | Information & communication | 2021 |
| JF Painting and Decorating Limited | Construction | 2014 |
| JFA Quick Services Ltd | Transport & logistics | 2022 |
| Jgme Homes Ltd | Real estate | 2025 |
| JH Care Group Ltd | Health & social care | 2025 |
| Jh&Kh Consulting Limited | Professional & scientific | 2025 |
| JHA Support Ltd | Construction | 2025 |
| JHE Properties Limited | Real estate | 2015 |
| JHJ Bespoke Furniture Limited | Construction | 2012 |
| JHL Online Ltd | Wholesale & retail | 2023 |
| JHP Commercial Services Ltd | Professional & scientific | 2026 |
| Jiadella Ltd | Wholesale & retail | 2015 |
| Jiconnect Education Agency Ltd | Education | 2025 |
| Jigsaw Education & Business Consultants Ltd | Professional & scientific | 2014 |
| Jimmy's Fireworks Limited | Wholesale & retail | 2003 |
| JIR Construction Limited | Construction | 2006 |
| JJ & L Limited | Real estate | 2025 |
| JJ Automation Limited | Construction | 2014 |
| JJ Elite Construction Ltd | Construction | 2018 |
| JJ Weddings Limited | Information & communication | 2021 |
| Jj's Scaffolding Ltd | Construction | 2009 |
| Jj's Tyre Shop Ltd | Wholesale & retail | 2023 |
| Jj's Tyres Limited | Wholesale & retail | 2016 |
| JJA Pack Ltd | Manufacturing | 2012 |
| JJA Snack Ltd | Manufacturing | 2023 |
| JJA Track Ltd | Manufacturing | 2022 |
| JJB Homes (Yorkshire) Ltd | Construction | 2024 |
| JJR Holdings Limited | Financial services | 2026 |
| Jjsd Projects Ltd | Construction | 2017 |
| JK Machinery Limited | Manufacturing | 1989 |
| Jkcleanz Ltd | Administrative & support | 2025 |
| JKD Electrical Ltd | Construction | 2024 |
| Jkemo Limited | Health & social care | 2022 |
| JKL Properties & Management Limited | Real estate | 2020 |
| JKM Windows & Doors Ltd | Construction | 2026 |
| JKR Property Development Limited | Construction | 2013 |
| JL Comms Ltd | Information & communication | 2026 |
| JL Family Retail Ltd | Wholesale & retail | 2022 |
| JLC Building Services & Project Management Limited | Construction | 2014 |
| JLC Farming Limited | Agriculture & fishing | 2015 |
| JLC Padel Hub Ltd | Arts & recreation | 2026 |
| JLF Ventures Limited | Wholesale & retail | 2014 |
| JLP Distribution Limited | Other services | 2003 |
| Jlsadler-Np Ltd | Health & social care | 2019 |
| JLV Groundworks & Plant Hire Limited | Manufacturing | 2025 |
| JM Energy Services Ltd | Energy | 2024 |
| JM Management Limited | Administrative & support | 2014 |
| JM Mech&Elec Limited | Professional & scientific | 2024 |
| JMC AMZ Ltd | Wholesale & retail | 2025 |
| JMC Analysis Ltd | Administrative & support | 2014 |
| JMC ENG Ltd | Professional & scientific | 2025 |
| JMC FBA Ltd | Wholesale & retail | 2023 |
| JMC Resell Ltd | Wholesale & retail | 2023 |
| JMH Financial Services Ltd | Financial services | 2023 |
| JMS Construction Management & Consultants Ltd | Professional & scientific | 2026 |
| JMT Transport Limited | Transport & logistics | 2014 |
| JNA Heating and Renewables Ltd | Construction | 2023 |
| JNA Property Holdings Limited | Real estate | 2025 |
| JO Poskitt Aesthetics Ltd | Health & social care | 2021 |
| Joanne Outwin Ltd | Extraterritorial | 2024 |
| Jobandknock Ltd | Construction | 2015 |
| Joburns Roofing & Maintenance Limited | Construction | 2025 |
| Jodam Construction Ltd | Construction | 2015 |
| Jodam Holdings Ltd | Financial services | 2025 |
| Jodam Properties Limited | Real estate | 2016 |
| JOE Pole Investments Limited | Other services | 2015 |
| JOE Pole Storage Limited | Real estate | 1975 |
| JOE Wilkinson Clothing Limited | Wholesale & retail | 2016 |
| Joel Mann Heating Ltd | Construction | 2025 |
| Joel Wright Limited | Extraterritorial | 2024 |
| Joes Autos Limited | Wholesale & retail | 2019 |
| Johal Bites Ltd | Hospitality | 2025 |
| Johal Couriers Ltd | Transport & logistics | 2018 |
| Johdina Consult Limited | Wholesale & retail | 2016 |
| John Donnachie Roofing & Building Contractor Limited | Construction | 2016 |
| John Driver's Hire Limited | Administrative & support | 2015 |
| John Goodyear and Company Limited | Professional & scientific | 1996 |
| John Griffin Mortgage Services Ltd | Financial services | 2024 |
| John Higgins (Barnsley) Ltd | Transport & logistics | 2018 |
| John Longley Kitchens and Bathrooms (Holdings) Limited | Financial services | 2015 |
| John Murphy Joinery Ltd | Construction | 2026 |
| John Parker Joinery Limited | Construction | 2012 |
| John Truswell & Sons(Haulage)Limited | Extraterritorial | 1966 |
| John Walton Engraving Limited | Manufacturing | 2004 |
| Johnson Electrical Yorkshire Ltd | Construction | 2024 |
| Johnson Family Investments Limited | Real estate | 2021 |
| Johnsons Building Services Ltd (Yorkshire) Ltd | Construction | 2026 |
| Johnsons Shoes (Farnham) Ltd | Real estate | 2020 |