| Jarvis Park Homes Ltd | Households | 2022 |
| Jarvis Portman Limited | Administrative & support | 2024 |
| Jarvis Pricing Ltd | Professional & scientific | 2026 |
| Jasani & Co Consulting Ltd | Professional & scientific | 2015 |
| Jask International Limited | Real estate | 2022 |
| Jasmin Elen Trading Limited | Wholesale & retail | 2025 |
| Jasmin Goods Trading Limited | Wholesale & retail | 2025 |
| Jasmin International Trading Co., Limited | Wholesale & retail | 2020 |
| Jasmin Land Trading Limited | Wholesale & retail | 2018 |
| Jasmin LEO Trading Limited | Wholesale & retail | 2025 |
| Jasmin Palace Trading Limited | Wholesale & retail | 2018 |
| Jasmin World Trading Limited | Wholesale & retail | 2025 |
| Jasmine Nngf Limited | Manufacturing | 2025 |
| Jason Kirby Painting and Decorating Limited | Professional & scientific | 2004 |
| Jason Moore Carpentry & Building Limited | Construction | 2013 |
| Jason Technologies Ltd | Extraterritorial | 2013 |
| Jasper Byrne Limited | Manufacturing | 1991 |
| Jasper Medical Ltd | Health & social care | 2024 |
| Jasper Taxation Services Ltd. | Professional & scientific | 2004 |
| Jaunty Bear Limited | Professional & scientific | 2024 |
| Javan Hughes Limited | Information & communication | 2019 |
| Jawharah Ltd | Wholesale & retail | 2024 |
| JAY EYE Sea Limited | Professional & scientific | 2009 |
| Jay&Fri Ltd | Hospitality | 2022 |
| Jay's Automotive Services Limited | Wholesale & retail | 2023 |
| Jaystro Ltd | Wholesale & retail | 2023 |
| Jayworth House Limited | Real estate | 2022 |
| Jayworth House Management Company Limited | Households | 1991 |
| Jay’S Fish Ltd | Hospitality | 2025 |
| JAZ Capital Limited | Financial services | 2026 |
| Jazo Residential Ltd | Real estate | 2026 |
| Jazz Cat Technology Limited | Manufacturing | 2025 |
| JB (Eastbourne) Ltd | Real estate | 2019 |
| JB Aviation Pro Ltd | Transport & logistics | 2013 |
| JB Education Ltd | Education | 2017 |
| JB Heritage Consulting Limited | Professional & scientific | 2020 |
| JBC Aligned Marketing Ltd | Professional & scientific | 2023 |
| JBF Ltd | Manufacturing | 2025 |
| JBG Premium Care Ltd | Health & social care | 2025 |
| JBL Int'L Consulting Limited | Professional & scientific | 2014 |
| Jbmochan Ltd | Manufacturing | 2025 |
| Jboca Associates Limited | Professional & scientific | 2012 |
| Jbrous Ltd | Manufacturing | 2024 |
| JBS Executive Education Limited | Education | 2006 |
| JBT Investments Limited | Financial services | 2018 |
| Jbuk (Belfast) Ltd | Real estate | 2023 |
| Jbuk (Braehead) Ltd | Real estate | 2021 |
| Jbuk (Forestside) Ltd | Real estate | 2022 |
| Jbuk (Gloucester) Ltd | Real estate | 2021 |
| Jbuk (Ilford) Ltd | Real estate | 2021 |
| Jbuk (Warrington) Ltd | Real estate | 2022 |
| Jbuk (Watford) Ltd | Real estate | 2022 |
| JC Consultants (Cambridge) Ltd | Professional & scientific | 2018 |
| JC Finance Solutions Ltd | Professional & scientific | 2017 |
| JC Optical Ltd | Health & social care | 2022 |
| JC UK Textiles Limited | Wholesale & retail | 2023 |
| Jcconstructionconsulting Ltd | Construction | 2025 |
| JCM Composite Ltd | Manufacturing | 2022 |
| JCS Estate Ltd | Households | 2022 |
| Jcsc Consulting Ltd | Information & communication | 2014 |
| JCT Holdings Ltd | Real estate | 2026 |
| JCT2007 Investment Ltd | Real estate | 2025 |
| JD Developments Cambridge Limited | Construction | 2017 |
| JD Helicopter Services Ltd | Manufacturing | 2022 |
| JDB Plastering Ltd. | Construction | 2019 |
| JDB Solutions Limited | Professional & scientific | 2024 |
| Jdecology Ltd | Professional & scientific | 2011 |
| JDM Talent Ltd | Administrative & support | 2021 |
| JDN Property Solution Ltd | Real estate | 2024 |
| Jech Business Services Limited | Construction | 2016 |
| Jeeps Close Roadway Ltd. | Households | 2012 |
| Jeeva Retail Ltd | Wholesale & retail | 2021 |
| JEF (UK) Ltd | Real estate | 2020 |
| Jeff Helme Thatching Services Limited | Construction | 2005 |
| Jefferson RAH Ltd | Real estate | 2025 |
| Jeffery Sinjon and Associates Limited | Wholesale & retail | 1977 |
| Jefford Properties Ltd | Real estate | 2013 |
| Jeffreys Brasserie Ltd | Hospitality | 2013 |
| Jelakip Limited | Health & social care | 2013 |
| Jelca Ltd | Professional & scientific | 2026 |
| Jelledo Limited | Households | 2003 |
| JEM Innovation Ltd. | Hospitality | 2013 |
| Jemego Ltd | Financial services | 2024 |
| Jemma Baker US Tax LLP | | 2024 |
| Jemms (UK) Ltd | Information & communication | 2012 |
| Jemporium Vintage Limited | Wholesale & retail | 2015 |
| Jenfo Trading Co., Ltd | Wholesale & retail | 2024 |
| Jenking LET Limited | Real estate | 2016 |
| Jenking Limited | Financial services | 2016 |
| Jenking Tech Limited | Professional & scientific | 2016 |
| Jenkins & Sons Property Solutions Ltd | Construction | 2026 |
| Jenkins and Beckers Fine Wine Limited | Wholesale & retail | 2015 |
| Jenkins Court Management Company Limited | Households | 2005 |
| Jens Automation Wizardry Ltd | Professional & scientific | 2026 |
| JER Advisory Limited | Professional & scientific | 2015 |
| JER Construction Limited | Construction | 2007 |
| Jeremy Parker Ltd | Wholesale & retail | 2024 |
| Jermyn Street Limited | Professional & scientific | 2019 |
| Jess Solace Ltd | Real estate | 2024 |
| Jessamy Jones Ltd | Professional & scientific | 2024 |