| JCM Facilities Management Limited | Administrative & support | 2016 |
| JCO Plumbing & Heating Ltd | Construction | 2024 |
| JCP Catering Ltd | Hospitality | 2026 |
| JCR Motorsport Ltd | Arts & recreation | 2015 |
| Jcslc Limited | Wholesale & retail | 2025 |
| JD Catering Ltd | Hospitality | 2026 |
| JD Kitchens and Bathrooms Limited | Construction | 2022 |
| JDC Promotions Ltd | Other services | 2024 |
| Jdent (SW) Limited | Health & social care | 2022 |
| JDL Automotive Ltd | Wholesale & retail | 2024 |
| JDL Refurbs Ltd | Construction | 2022 |
| Jdlgb Ltd | Professional & scientific | 2021 |
| JDM Holiday Properties Limited | Real estate | 2020 |
| JDR Medical Services Limited | Health & social care | 2022 |
| Jdtf Limited | Wholesale & retail | 2024 |
| Jeam Courier Ltd | Transport & logistics | 2017 |
| Jeanne Petitt Limited | Wholesale & retail | 1982 |
| JEB UK Property Ltd | Real estate | 2019 |
| JEC Adiuvo UK Ltd. | Real estate | 2007 |
| JEC Renovo FM Ltd | Real estate | 2022 |
| Jedd Group Limited | Wholesale & retail | 2026 |
| Jeevan IT Solutions Ltd | Information & communication | 2016 |
| Jeff Grinnell Ltd | Construction | 2017 |
| Jeffreys Developments Limited | Construction | 2012 |
| Jeffwilliams Rugby Ltd | Education | 2025 |
| Jehdi Ltd | Construction | 2016 |
| Jelcal Limited | Professional & scientific | 2018 |
| Jelly Armchair Ltd | Arts & recreation | 2015 |
| Jemco Developments Ltd | Construction | 2021 |
| Jempep Procurement Limited | Professional & scientific | 2008 |
| Jemray Ltd | Professional & scientific | 2024 |
| Jems Vinyl Art Limited | Wholesale & retail | 2019 |
| JEN Jenivive Ltd | Wholesale & retail | 2026 |
| Jenk Landscape Design + Planning Ltd | Professional & scientific | 2024 |
| Jenks Consulting Limited | Information & communication | 2015 |
| Jenna Elsby Ltd | Professional & scientific | 2021 |
| Jenna ZOE Limited | Health & social care | 2018 |
| Jennick Property Management Limited | Extraterritorial | 2014 |
| Jenny Wren Productions Limited | Arts & recreation | 2012 |
| JEP Ventures Limited | Professional & scientific | 2015 |
| Jepiphany Limited | Energy | 2023 |
| Jeremy Moore Associates Limited | Professional & scientific | 2002 |
| Jeremy Round Cars Limited | Wholesale & retail | 2005 |
| Jericho Innovations Limited | Professional & scientific | 2024 |
| Jericho Street (Oxford) Management Limited | Households | 2011 |
| JET Machining Solutions Ltd | Administrative & support | 2016 |
| JET Property Maintenance Ltd | Other services | 2022 |
| Jewelie Ltd | Wholesale & retail | 2021 |
| Jewell Building Ltd | Construction | 2022 |
| Jewson Holdings Limited | Real estate | 1983 |
| Jewson Investments Ltd | Other services | 2014 |
| Jeynes Farming Ltd | Agriculture & fishing | 2025 |
| JFB (South West) Limited | Construction | 2020 |
| JFC Cheltenham Limited | Wholesale & retail | 2026 |
| JFS Cheltenham Limited | Administrative & support | 2000 |
| JFS Consultancy Limited | Information & communication | 2015 |
| JG Enterprises Limited | Wholesale & retail | 2025 |
| JG Macclesfield Holdings Ltd | Professional & scientific | 2017 |
| JG Park Homes and Developments Ltd | Hospitality | 2021 |
| JG Travel Group Limited | Administrative & support | 2009 |
| JGA Safety Limited | Professional & scientific | 2017 |
| JGH Group Limited | Administrative & support | 2016 |
| JGH Midco Limited | Administrative & support | 2016 |
| JGH Topco Limited | Administrative & support | 2016 |
| JGK 2016 Ltd | Hospitality | 2016 |
| JGO Norman Limited | Wholesale & retail | 2010 |
| JH Accountancy & Financial Management Ltd | Professional & scientific | 2018 |
| JH Production Ltd | Information & communication | 2024 |
| JHE Consulting Limited | Professional & scientific | 2016 |
| JHE Services Limited | Professional & scientific | 2003 |
| JHH Solutions Limited | Professional & scientific | 2024 |
| JHP Electrical Ltd | Construction | 2019 |
| Jidlo Limited | Hospitality | 2019 |
| Jigsaw Consulting Ltd | Information & communication | 2025 |
| Jigsaw Property Services (Cheltenham) Limited | Construction | 2002 |
| JIM R Limited | Agriculture & fishing | 2025 |
| Jimc Technology Limited | Information & communication | 2023 |
| Jimmy White Limited | Arts & recreation | 2002 |
| Jiuji Sports UK Limited | Wholesale & retail | 2024 |
| Jjac Group Ltd | Financial services | 2025 |
| JJJA4 Ltd | Transport & logistics | 2025 |
| JJK International Ltd | Professional & scientific | 2025 |
| JJR Group Limited | Professional & scientific | 2023 |
| JJS Hair Group Ltd | Other services | 2023 |
| JJS Hair Salon Limited | Other services | 2013 |
| JK Helicopter Training Ltd | Transport & logistics | 2015 |
| JK Paints & Decorates Ltd | Construction | 2025 |
| JK Psychology Ltd | Education | 2024 |
| JK Solid Security Services Limited | Administrative & support | 2025 |
| JKD Studio Ltd | Professional & scientific | 2019 |
| JKP Properties Limited | Real estate | 2017 |
| Jlec Ltd | Construction | 2018 |
| JLQ Investments Ltd | Financial services | 2020 |
| JLR Digital Communications Ltd | Information & communication | 2025 |
| Jlts (Projects) Ltd | Construction | 2015 |
| JM Accounting Services Limited | Professional & scientific | 1997 |
| JM Scientific Limited | Professional & scientific | 2022 |
| JM Socials Limited | Financial services | 2020 |
| JMC Properties Investments Ltd | Construction | 2024 |
| JMD Executive Search Limited | Administrative & support | 2022 |