| Jessica Rowley Limited | Education | 2023 |
| Jessica's Interiors Limited | Extraterritorial | 2013 |
| Jessycouture Ltd | Manufacturing | 2026 |
| Jestel OT Services Ltd | Health & social care | 2011 |
| Jester Associates LLP | | 2016 |
| Jesupara Properties Ltd | Real estate | 2020 |
| JET Aerospace Limited | Wholesale & retail | 2025 |
| JET Aviation Supplies Limited | Wholesale & retail | 2025 |
| JET Freight Logistics (UK) Ltd | Transport & logistics | 2020 |
| JET International Transport Aero Services Limited | Financial services | 1981 |
| Jetcom Investments Limited | Real estate | 1999 |
| Jetron Limited | Real estate | 2018 |
| Jett Painter and Build Ltd | Construction | 2025 |
| Jetway Limited | Administrative & support | 2016 |
| Jewel of Hertsmere Limited | Hospitality | 2015 |
| Jewellery 4 Elegance Ltd | Wholesale & retail | 2024 |
| Jewelrush Limited | Wholesale & retail | 2025 |
| Jewels Corporation Limited | Wholesale & retail | 2012 |
| Jeya RE Ltd | Real estate | 2026 |
| Jeyam Properties Ltd | Real estate | 2025 |
| JF Dooley Limited | Health & social care | 2010 |
| JF Market Strategies Limited | Administrative & support | 2014 |
| JF Securities London Limited | Administrative & support | 2016 |
| JF2 Properties Ltd | Real estate | 2026 |
| JFC Trading Limited | Wholesale & retail | 2014 |
| JFK Bradshaw Limited | Administrative & support | 2013 |
| JFL Retail Limited | Professional & scientific | 2013 |
| JFM Block & Estate Management LLP | | 2015 |
| JFM Block Management Ltd | Real estate | 2024 |
| JFM Intelligence Limited | Real estate | 2025 |
| JFS Charitable Trust Limited | Education | 2000 |
| JG Capital Development Ltd | Real estate | 2025 |
| JG Partnership Limited | Professional & scientific | 2022 |
| JGA Limited | Education | 2003 |
| JGJ Business Associates Limited | Professional & scientific | 2020 |
| JGJ Residential Limited | Real estate | 2018 |
| JGJ Resources Limited | Wholesale & retail | 2018 |
| JGJ Secmanprop Services Limited | Real estate | 2009 |
| JGS Retail Limited | Real estate | 2009 |
| JH and Family Capital Ltd | Financial services | 2018 |
| JH and Family H2 Ltd | Real estate | 2019 |
| JH and Family Holdings Limited | Real estate | 2016 |
| JH Asset Management Ltd | Financial services | 2022 |
| JH Electrical Specialist Limited | Construction | 2021 |
| JH Lighting Limited | Construction | 2014 |
| JH Malls Services Limited | Construction | 2017 |
| JH Real Assets Limited | Professional & scientific | 2020 |
| Jhdt Investments Limited | Real estate | 2018 |
| JHK Investments Limited | Real estate | 2020 |
| JHR Property Limited | Real estate | 2016 |
| JHT Galacticos Limited | Financial services | 2018 |
| Jhyc Ltd | Professional & scientific | 2024 |
| Jian Consulting Ltd | Construction | 2013 |
| Jiastar Ltd | Real estate | 2026 |
| Jigajera Ltd | Wholesale & retail | 2026 |
| Jigsaw Bespoke Joinery Limited | Construction | 2024 |
| Jigsaw Pixel Assets Limited | Real estate | 2019 |
| Jigsaw Pixel Limited | Information & communication | 2013 |
| Jigsaw Wholesale Ltd. | Other services | 2002 |
| Jigy Limited | Professional & scientific | 2006 |
| Jikoni Limited | Hospitality | 2016 |
| Jimmy Murphy Limited | Hospitality | 2021 |
| Jimseng Limited | Public administration | 2020 |
| Jinda Jewellers Limited | Manufacturing | 2022 |
| Jitlaw Ltd | Professional & scientific | 2013 |
| Jitride Ltd | Professional & scientific | 2024 |
| Jitta Properties Limited | Other services | 2007 |
| Jitu Dattani Consultancy Limited | Professional & scientific | 2024 |
| Jiva Care Recruitment Ltd | Administrative & support | 2020 |
| Jiwani Solutions Ltd | Professional & scientific | 2012 |
| Jiwil Ltd | Real estate | 2021 |
| Jiya Food Hub Ltd | Hospitality | 2025 |
| Jiya Naksh Limited | Wholesale & retail | 2021 |
| Jiya Naturals Ltd | Wholesale & retail | 2024 |
| Jiyansh Capital & Estates Ltd | Real estate | 2025 |
| Jiyas Properties Limited | Real estate | 2025 |
| JJ Chauffeuring Services (UK) Limited | Transport & logistics | 2002 |
| JJ Estate Holdings Ltd | Real estate | 2021 |
| JJ Parties Limited | Arts & recreation | 2017 |
| JJ Sweets Limited | Hospitality | 2018 |
| JJC Consultants (London) Ltd | Real estate | 2018 |
| JJF Group Ltd | Construction | 2015 |
| Jjgrademedia Limited | Information & communication | 2019 |
| JJJ Build Masters Limited | Construction | 2026 |
| JJM Builders Ltd | Construction | 2024 |
| JJM London Ltd | Real estate | 2017 |
| JJM Plumbing Limited | Construction | 2023 |
| JJR Property Developments Limited | Construction | 2020 |
| JJS Developments Limited | Real estate | 2015 |
| Jjungl Limited | Administrative & support | 2021 |
| JK Deep Limited | Wholesale & retail | 2026 |
| JK Deep Private Limited | Wholesale & retail | 2026 |
| JK Kaiser Ltd | Transport & logistics | 2020 |
| JK Premier Estates Limited | Real estate | 2025 |
| JK Windows UK Ltd | Construction | 2025 |
| Jkammer Software Ltd | Information & communication | 2014 |
| JKB Consultancy Ltd | Financial services | 2022 |
| Jkhallaf Limited | Information & communication | 2015 |
| Jklm Consultancy Ltd | Administrative & support | 2024 |
| Jklp Limited | Professional & scientific | 2018 |