| JAF Builders Ltd | Construction | 2023 |
| JAF Catering Limited | Hospitality | 2023 |
| JAG Property (Horbury) Ltd | Real estate | 2023 |
| JAG Wallcoating Limited | Construction | 2021 |
| JAI P Property Ltd | Real estate | 2025 |
| Jai's Takeaway Ltd | Hospitality | 2018 |
| JAK Collective Limited | Wholesale & retail | 2025 |
| Jaluben Limited | Professional & scientific | 2016 |
| James and Harry Marketing Network Ltd | Extraterritorial | 2019 |
| James Ashley Homes Ltd | Real estate | 2026 |
| James Morrison & SON Ltd | Construction | 2022 |
| James Phillips Coaching Ltd | Arts & recreation | 2022 |
| James Shilling Limited | Health & social care | 2016 |
| James Street (Management Company) Limited | Households | 2019 |
| James Thewsey Ltd | Transport & logistics | 2019 |
| Jamfestival Ltd | Hospitality | 2025 |
| Jamia Masjid Swafia | Other services | 2013 |
| Jamia Rizvia Misbah UL Quran Limited | Education | 2019 |
| Jamtails Limited | Information & communication | 2013 |
| JAN & R Ltd | Real estate | 2013 |
| JAN & R Medical Ltd | Health & social care | 2014 |
| JAN Financial Planning Limited | Extraterritorial | 2019 |
| Janil Investment Limited | Administrative & support | 2005 |
| Jano Transport Ltd | Transport & logistics | 2026 |
| Jarrett Holmes Internal Solutions Limited | Construction | 2016 |
| Jarvis Johnson Limited | Professional & scientific | 1999 |
| Jaslarz & Stezaly Ltd | Real estate | 2019 |
| Jasma Yorks LLP | | 2024 |
| Jason & Daniel Properties Ltd | Real estate | 2023 |
| Jason Glaves Electrical Consultants Limited | Construction | 2021 |
| Jason Staniforth Ltd | Professional & scientific | 2022 |
| Javed Khan Limited | Health & social care | 2008 |
| JAY Dee's Fast Food Ltd | Hospitality | 2025 |
| Jay's Eat's Yorkshire Ltd | Hospitality | 2025 |
| Jaya IT Ltd | Health & social care | 2023 |
| Jayfarm Limited | Professional & scientific | 1992 |
| Jayne James Training and Consultancy Ltd | Professional & scientific | 2019 |
| Jays Trading Ltd | Wholesale & retail | 2010 |
| JB Furniture (Online) Limited | Wholesale & retail | 2021 |
| JB Furniture Limited | Wholesale & retail | 2009 |
| JB Leisure Limited | Real estate | 2021 |
| JC Attractions Ltd | Arts & recreation | 2019 |
| JC Fabrication & Engineering Limited | Manufacturing | 2020 |
| JC Image & Film Co Ltd | Professional & scientific | 2014 |
| Jcadia Ltd | Extraterritorial | 2017 |
| JCE Refrigeration Ltd | Energy | 2003 |
| JCG Design Ltd | Professional & scientific | 2019 |
| JCH Belper Limited | Other services | 2024 |
| JCH Otley Limited | Other services | 2026 |
| JCH Plumbing & Heating Ltd | Construction | 2020 |
| Jcone Care Limited | Extraterritorial | 2024 |
| JCS Brickwork Limited | Construction | 2018 |
| JCT Holdings Wakefield Ltd | Financial services | 2019 |
| JD Medical Agency Limited | Health & social care | 2012 |
| JDA Trans Ltd | Transport & logistics | 2016 |
| JDC Music Limited | Information & communication | 2014 |
| JDK Rentals Ltd | Real estate | 2026 |
| JDM Social Work Solutions Ltd | Health & social care | 2024 |
| JDO Media Ltd | Information & communication | 2022 |
| JDP Plumbing & Heating Limited | Construction | 2026 |
| JE 32 Property Investments Limited | Real estate | 2018 |
| JE Essentials Ltd | Wholesale & retail | 2025 |
| JE32 Property Services Ltd | Real estate | 2019 |
| Jeeby Jeeb Property Ltd | Real estate | 2025 |
| Jeffery Brothers Limited | Financial services | 2025 |
| Jehb Properties Ltd | Real estate | 2023 |
| JEL Financial Planning Ltd | Financial services | 2021 |
| Jelg Properties Limited | Construction | 2023 |
| Jellie Properties Limited | Real estate | 2016 |
| Jelly Direct Limited | Transport & logistics | 2024 |
| JEM Business Energy Ltd | Professional & scientific | 2017 |
| Jemmtec FIC | Financial services | 2022 |
| JEN Jen's Caribbean Kitchen Ltd | Hospitality | 2021 |
| Jenkar (UK) Limited | Financial services | 2011 |
| Jenkar Properties Ltd | Real estate | 2006 |
| Jenkar Shipping Limited | Transport & logistics | 1978 |
| Jenny Investments Limited | Real estate | 2015 |
| Jens Eggert Ltd. | Professional & scientific | 2017 |
| JEO Holdings Ltd | Real estate | 2022 |
| Jepp Associates Limited | Professional & scientific | 2025 |
| Jepp Axis Limited | Households | 2025 |
| Jepp Brunswick Ltd | Households | 2025 |
| Jepp Hindle Ltd | Real estate | 2025 |
| Jepp Hindle Properties Ltd | Real estate | 2026 |
| Jepp International Limited | Households | 2023 |
| Jepp Old School Holding Ltd | Other services | 2024 |
| Jepp School Court Limited | Households | 2024 |
| Jepp School House Ltd | Households | 2025 |
| Jepp Yeadon House Limited | Households | 2023 |
| JER Associates Management Limited | Professional & scientific | 2017 |
| Jesenco Limited | Professional & scientific | 2017 |
| Jess Electrical Ltd | Construction | 2025 |
| Jetkind Limited | | 1985 |
| Jeya Investments Ltd | Real estate | 2022 |
| JFC (Yorkshire) Ltd | Other services | 2016 |
| JFC Heron Ltd | Transport & logistics | 2017 |
| JFP Installations (North East) Limited | Construction | 2020 |
| JFP Installations (North West) Limited | Construction | 2020 |
| JGB Electrical Contractors Ltd | Construction | 2008 |
| Jgpower Limited | Manufacturing | 2005 |