| Jamie Lewis Residential Lettings Limited | Real estate | 2009 |
| Jamila's Legacy CIC | Education | 2022 |
| Jammu Builders Limited | Real estate | 2024 |
| Jamra Limited | Real estate | 2021 |
| Jamuna Supermarket Limited | Wholesale & retail | 2019 |
| JAN & Sach Hotels Ltd | Hospitality | 2021 |
| JAN Property Management Ltd | Real estate | 2024 |
| Jane Asega Limited | Health & social care | 2022 |
| Jane Holroyd Consultancy Ltd | Professional & scientific | 2010 |
| Jane Mayne Ltd | Professional & scientific | 2024 |
| Janellen Software Ltd | Information & communication | 2025 |
| Janesconsultancy Ltd | Professional & scientific | 2014 |
| Janet G & Sons LLP | | 2023 |
| Janet N Kaur Ltd | Real estate | 2022 |
| Janet Willars Ltd | Administrative & support | 2013 |
| Jangam Ltd | Health & social care | 2022 |
| Jani Associates Limited | Real estate | 2017 |
| Jani Design Ltd | Professional & scientific | 2016 |
| Janki Ltd | Health & social care | 2004 |
| Jannat Homecare Services Ltd | Health & social care | 2021 |
| Jannock Limited | Manufacturing | 2017 |
| Janoo Patel Hair & Makeup Limited | Other services | 2020 |
| Janos Building Services Limited | Construction | 2025 |
| Jansclean Limited | Administrative & support | 2017 |
| Janspeed Ltd | Wholesale & retail | 2022 |
| Janvi Optical Limited | Health & social care | 2024 |
| JAP Haulage Limited | Transport & logistics | 2025 |
| JAP Multani UK Limited | Hospitality | 2018 |
| Japan Car Importers Ltd | Wholesale & retail | 2023 |
| JAQ Asset Holdings Ltd | Professional & scientific | 2026 |
| JAR Auto Ltd | Wholesale & retail | 2026 |
| Jaral Ltd | Wholesale & retail | 2022 |
| Jardosh Properties Ltd | Real estate | 2020 |
| Jardssss Ltd | Administrative & support | 2025 |
| Jarian Investments Ltd | Real estate | 2001 |
| Jarinvestco Limited | Financial services | 2019 |
| Jarjam Limited | Financial services | 2024 |
| Jaro. H Trans Ltd | Transport & logistics | 2024 |
| Jarrod Bowen Sports Marketing Limited | Professional & scientific | 2016 |
| Jarroms Holdings Limited | Professional & scientific | 2024 |
| Jarroms Limited | Real estate | 2001 |
| Jarvis Cars Limited | Wholesale & retail | 2009 |
| Jarvis Energy Ltd | Professional & scientific | 2025 |
| Jarvis-Karia Ltd | Real estate | 2018 |
| JAS Analytics Ltd | Information & communication | 2019 |
| JAS Auto Panels & Accessories Limited | Wholesale & retail | 2006 |
| JAS Food & Drinks Ltd | Hospitality | 2018 |
| JAS Johal Properties Ltd | Real estate | 2025 |
| JAS News & Booze Limited | Wholesale & retail | 2025 |
| JAS Supermarket (EM) Ltd | Wholesale & retail | 2020 |
| JAS West Midlands Ltd | Real estate | 2017 |
| Jasa Cleaning Services Ltd | Administrative & support | 2020 |
| Jasdev Taxii Ltd | Transport & logistics | 2024 |
| Jash (Walsall) 2 Limited | Wholesale & retail | 2007 |
| Jash (Walsall) Limited | Financial services | 2006 |
| Jashaan Limited | Hospitality | 2024 |
| Jaskaran Construction Ltd | Construction | 2023 |
| Jaskirat Group Ltd | Transport & logistics | 2023 |
| Jasman Electrics Ltd | Manufacturing | 2021 |
| Jasman Properties Limited | Real estate | 2026 |
| Jasman Sangha Limited | Construction | 2023 |
| Jasmic Retail Ltd | Wholesale & retail | 2019 |
| Jasmin Design Limited | Extraterritorial | 2020 |
| Jasmine & Honey Ltd | Hospitality | 2026 |
| Jasmine for Import and Export of ALL Agricultural Products Ltd | Wholesale & retail | 2025 |
| Jasmine Medical Services Ltd | Health & social care | 2017 |
| Jasmine Property Management Limited | Real estate | 2017 |
| Jasmo Holdings Limited | Real estate | 2018 |
| Jasmo Ltd | Manufacturing | 2024 |
| Jason Dias Optometry Ltd | Health & social care | 2022 |
| Jason Kesh Limited | Manufacturing | 2010 |
| Jason Lynch Limited | Financial services | 2019 |
| Jason Lynch Property Investments Limited | Hospitality | 2020 |
| Jasp Property Investment and Rental Limited | Real estate | 2010 |
| Jaspreet & Co Real Estate Ltd | Real estate | 2025 |
| Jass Haulage Ltd | Wholesale & retail | 2025 |
| Jass Transport Limited | Transport & logistics | 2018 |
| Jassat Consulting Ltd | Other services | 2019 |
| Jassi Smiles Ltd | Health & social care | 2026 |
| Jastal Group Ltd | Hospitality | 2024 |
| Jaswal Fashions Limited | Professional & scientific | 2007 |
| JAT Hanspal Consulting Ltd | Information & communication | 2025 |
| Jatec IT Service Limited | Information & communication | 2007 |
| Jateen Vagani Wealth Management Limited | Financial services | 2013 |
| Jatha Transport Ltd | Transport & logistics | 2012 |
| Jatinder Gill Commercial Finance Ltd | Financial services | 2026 |
| Jatinder Gill Management Company Ltd | Financial services | 2026 |
| Jatinder Gill Mortgage and Protection Ltd | Financial services | 2022 |
| Jattscaffolding Limited | Construction | 2023 |
| Jaunius Transport Ltd | Transport & logistics | 2017 |
| Java Asset Management Limited | Real estate | 2007 |
| Javaspace Limited | Real estate | 2009 |
| Javed Fashion Ltd | Other services | 2016 |
| Javeed&N Limited | Wholesale & retail | 2025 |
| Javraj Dhaliwal Ltd | Health & social care | 2022 |
| Jawadnazir Ltd | Wholesale & retail | 2024 |
| Jawh Productions Ltd | Administrative & support | 2023 |
| Jaxon Properties Ltd | Real estate | 2006 |
| Jaxon Rose Limited | Construction | 2020 |
| JAY & B Services Limited | Wholesale & retail | 2014 |