| J'Sp Corporation Ltd | Hospitality | 2024 |
| J.A.Ceilings Ltd | Agriculture & fishing | 2008 |
| J.A.Y Creations Ltd | Information & communication | 2025 |
| J.D.L Supplies Ltd | Wholesale & retail | 2025 |
| J2H Food Ltd | Wholesale & retail | 2022 |
| J3 Tradings UK Ltd | Manufacturing | 2017 |
| J3S Global Limited | Administrative & support | 2026 |
| J4H Civil Engineering Limited | Construction | 2023 |
| Jaan UK Meat Ltd | Wholesale & retail | 2023 |
| Jack D International Limited | Manufacturing | 2008 |
| JACKIEAS0N Ltd | Other services | 2024 |
| Jag-Ufs (International) Limited | Transport & logistics | 1988 |
| Jagman Properties Limited | Real estate | 2015 |
| JAI Shree Mahadev Limited | Wholesale & retail | 2025 |
| Jaineet UK Limited | Wholesale & retail | 2006 |
| Jake Gregory Ltd | Transport & logistics | 2018 |
| Jampro Ltd | Hospitality | 2024 |
| Jamtart & Pegasus Limited | Professional & scientific | 2013 |
| Janaqisart Ltd | Construction | 2020 |
| Jand Construction Limited | Professional & scientific | 2017 |
| Jandu 76 Property Ltd | Real estate | 2025 |
| Jansev Estates Ltd | Real estate | 2025 |
| Japjot Building Services Ltd | Construction | 2023 |
| Jary International Ltd | Wholesale & retail | 2022 |
| JAS Beauty & Hair Studio Limited | Other services | 2024 |
| JAS Forwarding (UK) Limited | Transport & logistics | 1984 |
| JAS Hair &Beauty Limited | Other services | 2018 |
| JAS Skin Pro Ltd | Other services | 2026 |
| JAS UK Holding Limited | Transport & logistics | 2025 |
| Jaseet Limited | Construction | 2025 |
| Jash Infotech Ltd | Information & communication | 2018 |
| Jasroop Ltd | Real estate | 2024 |
| Jass Construction Ltd | Construction | 2021 |
| Jaszone Properties Limited | Wholesale & retail | 2024 |
| Jawahar & Diwan Properties Limited | Real estate | 2026 |
| Jawaid Ltd | Health & social care | 2022 |
| Jawaidhr Limited | Professional & scientific | 2017 |
| Jawani Clothing Limited | Manufacturing | 2025 |
| JAY Haulage Ltd | Transport & logistics | 2023 |
| Jayden Property Management Ltd | Real estate | 2020 |
| Jayman Enterprises Ltd | Wholesale & retail | 2011 |
| Jays Install Ltd | Construction | 2021 |
| Jaywood Electro Plating Company Limited | | 1959 |
| Jazar Media Limited | Professional & scientific | 2025 |
| Jazz Flowers Contracts and Events Limited | Wholesale & retail | 2012 |
| Jazz Food & Wine Limited | Wholesale & retail | 2025 |
| Jazza G Ltd | Wholesale & retail | 2026 |
| Jazzy Phones & Tech Limited | Wholesale & retail | 2025 |
| JB Installations Ltd | Information & communication | 2012 |
| Jb&Sa Limited | Real estate | 2025 |
| JBL Furniture Interiors and Design Limited | Manufacturing | 2002 |
| JBN Gentle Care Services Ltd | Health & social care | 2025 |
| JBR Foods Limited | Hospitality | 2022 |
| JC Courier Express Ltd | Transport & logistics | 2017 |
| JC Roofing (Middlesex) Limited | Construction | 2014 |
| JD Boss Ltd | Real estate | 2021 |
| JD CAD CAM Services Limited | Professional & scientific | 2025 |
| JD Distributors Ltd | Wholesale & retail | 2025 |
| JDH UK Investments Ltd | Real estate | 2021 |
| JDI Care Limited | Health & social care | 2021 |
| Jeelz Events Ltd | Wholesale & retail | 2023 |
| Jeevsra Estates Ltd | Real estate | 2024 |
| Jeevsra Nexus Ltd | Real estate | 2023 |
| Jenner Medical Consultancy Ltd | Public administration | 2023 |
| Jerac Ltd | Public administration | 2022 |
| Jesmond House Holdings Ltd. | Financial services | 2015 |
| Jessett & Henry(Food Machinery)Limited | | 1959 |
| Jessi Heer Builders Ltd | Construction | 2019 |
| Jessklin Limited | Manufacturing | 2015 |
| Jesus IS Love Jesus IS Lord Ltd | Other services | 2015 |
| JET Fares Limited | Administrative & support | 2025 |
| JEWELLERY4ALL Limited | Real estate | 2026 |
| JFH Management Services Ltd | Professional & scientific | 2025 |
| JHA Trading Ltd | Financial services | 2026 |
| Jhooti’S ABS Limited | Arts & recreation | 2025 |
| JHS Sushi Ltd | Hospitality | 2023 |
| Jinhaiyuan UK Limited | Wholesale & retail | 2025 |
| Jinsei Limited | Wholesale & retail | 2018 |
| JIS Windscreen Solution Ltd | Wholesale & retail | 2025 |
| Jitten Panchal Limited | Information & communication | 2018 |
| JJ Business Consultancy & Partnering Ltd | Professional & scientific | 2016 |
| JJ Groceries Ltd | Wholesale & retail | 2024 |
| JJ Group Constructions Ltd | Construction | 2022 |
| JJ Will Writers Ltd | Information & communication | 2024 |
| JK Calisthenics Ltd | Arts & recreation | 2026 |
| JK United Ltd | Administrative & support | 2026 |
| JKB IT Consulting Limited | Information & communication | 2021 |
| JKS Convenience Store Ltd | Wholesale & retail | 2021 |
| JL Construction Services Limited | Professional & scientific | 2018 |
| JLK Group Limited | Construction | 2018 |
| JM Globis Solution Ltd | Wholesale & retail | 2015 |
| JMG Communication Limited | Transport & logistics | 2021 |
| Jmvd Ltd | Transport & logistics | 2024 |
| JNR Wave Limited | Wholesale & retail | 2025 |
| Joannamedical Limited | Health & social care | 2023 |
| John & Yuki Trading Ltd | Wholesale & retail | 2024 |
| John Mills Violinist Ltd | Arts & recreation | 2019 |
| John.Construc. Ltd | Construction | 2025 |
| Join Construction Ltd | Construction | 2019 |
| Jolly Foods (UK) Ltd | Transport & logistics | 2022 |