| Jackson Electrical Services & Contractors Ltd | Construction | 2010 |
| Jaiya Bhandari Ltd | Real estate | 2021 |
| Jake's Bar Ltd | Hospitality | 2023 |
| James Barnes Education Ltd | Education | 2015 |
| James Gilmour and Partners LLP | | 2009 |
| James Hampshire Ltd | Construction | 2021 |
| James Harvey Consultancy Ltd | Administrative & support | 2015 |
| James Plastering Services Ltd | Construction | 2023 |
| James Retail Holdings Limited | Professional & scientific | 2015 |
| Jane Morrey Music Limited | Education | 2002 |
| Janet Fisher Education Limited | Education | 2019 |
| Jans Property Developments Limited | Real estate | 2019 |
| Janus Prasvien Ltd | Professional & scientific | 2019 |
| Janus Solutions Ltd | Financial services | 2004 |
| Jark Group Holdings Limited | Real estate | 2023 |
| Jark Group Limited | Professional & scientific | 2022 |
| Jasmine Khatun Beauty Limited | Wholesale & retail | 2018 |
| Jason Monaghan Contracting Limited | Information & communication | 2024 |
| Jaton Trading Ltd | Wholesale & retail | 2025 |
| Jave Group Ltd | Construction | 2024 |
| Jaxi's Cozy Quarters Ltd | Real estate | 2026 |
| JAY Tea Limited | Hospitality | 2009 |
| Jaymire Limited | Wholesale & retail | 2018 |
| JB Fortified Ltd | Arts & recreation | 2024 |
| Jbap Consulting Ltd | Information & communication | 2010 |
| Jbrt Limited | Professional & scientific | 2013 |
| JBT Solutions Limited | Professional & scientific | 2008 |
| JC Academy Ltd | Arts & recreation | 2013 |
| JCT Computer Software Ltd | Information & communication | 2022 |
| JD Engineering Supplies Limited | Wholesale & retail | 2013 |
| JD Kitchens (Dorset) Limited | Construction | 2014 |
| JD Therapist Limited | Health & social care | 2017 |
| JDM Plumbing Ltd | Construction | 2022 |
| Jdpf Group Ltd | Financial services | 2026 |
| Jdpf Ltd | Construction | 2025 |
| Jdpf Properties Ltd | Real estate | 2026 |
| JDR Driveways Limited | Construction | 2021 |
| JDS Electrical (UK) Limited | Construction | 2003 |
| Jem's Floral Studio Ltd | Wholesale & retail | 2021 |
| Jemandco Ltd | Wholesale & retail | 2023 |
| Jennings Family Holdings Ltd | Financial services | 2025 |
| Jenny Marriott Mortgages Limited | Financial services | 2024 |
| Jera Enterprises Limited | Information & communication | 2003 |
| Jerome Rendering Limited | Construction | 2004 |
| JET Safe Ltd | Administrative & support | 2024 |
| JGM Support Ltd | Administrative & support | 2023 |
| JH & SM Ltd | Professional & scientific | 2021 |
| JH Automatics Limited | Administrative & support | 2021 |
| JH Human Factors Ltd | Professional & scientific | 2019 |
| JIM Dickens Limited | Wholesale & retail | 2019 |
| JJ Cooper Properties Limited | Real estate | 2022 |
| JJ Monaghan Watches Ltd | Wholesale & retail | 2020 |
| JJ Premium Cars Ltd | Wholesale & retail | 2014 |
| JJ PUB Management Limited | Hospitality | 2020 |
| JJB Car Sales Limited | Wholesale & retail | 2025 |
| Jjfmartial Arts Ltd | Arts & recreation | 2024 |
| JKM Performance Limited | Real estate | 2018 |
| JL Autos (Services) Limited | Wholesale & retail | 2023 |
| JL Construction Midlands Limited | Construction | 2024 |
| JLA Veterinary Services Limited | Professional & scientific | 2016 |
| JLE Group Ltd | Financial services | 2017 |
| JLE Holdco Ltd | Financial services | 2021 |
| JLE Newco Ltd | Financial services | 2021 |
| JLE Property Ltd. | Real estate | 2019 |
| JLE Ventures (Lindon Phase 1) Limited | Construction | 2023 |
| JLE Ventures (Long Lane) Limited | Construction | 2023 |
| JLE Ventures Ltd | Construction | 2003 |
| JLE Ventures PE Limited | Financial services | 2022 |
| Jliral Food Ltd | Wholesale & retail | 2021 |
| JLS Sport Holdings Limited | Professional & scientific | 2003 |
| JM Designs Limited | Administrative & support | 2024 |
| JM Spraybooth Installations Limited | Manufacturing | 2021 |
| JM Training Academy Limited | Administrative & support | 2024 |
| JMC Executive Connections Ltd | Transport & logistics | 2015 |
| JMD Property Investments Limited | Real estate | 2018 |
| JMF Dynamic Ltd | Administrative & support | 2021 |
| JMT Jones Ltd | Real estate | 2019 |
| Jobmatcho Ltd | Administrative & support | 2020 |
| Jofemar UK Limited | Administrative & support | 2005 |
| John Brown Nurseries Limited | Agriculture & fishing | 2001 |
| John Dixon Meat Wholesalers (Chase Terrace) Limited | Wholesale & retail | 1978 |
| John E Cole Enterprises Ltd | Construction | 2015 |
| John Hicken Limited | Professional & scientific | 1949 |
| John Kingslake (Farms) Limited | Financial services | 1997 |
| John Kingslake Limited | Agriculture & fishing | 1959 |
| John Poulton Transport Services Limited | Transport & logistics | 2006 |
| John Sutton Greenacres Ltd | Administrative & support | 2001 |
| Johnsons of Lichfield Holdings Limited | Financial services | 2023 |
| Johnsons of Lichfield Limited | Real estate | 2001 |
| Joincare Ltd | Construction | 2024 |
| Joipaw Ltd | Information & communication | 2022 |
| JON Robinson & Sons Ltd | Transport & logistics | 2022 |
| Jonathan Loescher & Co. Limited | Professional & scientific | 2002 |
| Jones Holmes Developments Limited | Construction | 2017 |
| Jones Waste Holdings Limited | Financial services | 2015 |
| Jorlareo Ltd | Transport & logistics | 2019 |
| Josephs Pilates Limited | Arts & recreation | 2024 |
| Joshua DA Costa Fitness Ltd | Education | 2019 |
| Joss Musgrove Knibb Ltd | Manufacturing | 2025 |
| Journeys Removals Ltd | Transport & logistics | 2020 |