| Jaynarayan Electircs Limited | Construction | 2017 |
| Jayneeth Properties Limited | Real estate | 2000 |
| Jays Estate Property Development Ltd | Real estate | 2017 |
| Jays Tree Care Limited | Administrative & support | 2020 |
| Jaysam Design & Interiors Limited | Administrative & support | 2015 |
| Jaysam Developments Wembley Limited | Construction | 2014 |
| Jaysam Joinery Limited | Real estate | 1988 |
| Jaysan Limited | Professional & scientific | 2020 |
| Jayshah & Associates Limited | Health & social care | 2008 |
| Jaysons Investments Ltd | Real estate | 2015 |
| Jaysons Ltd | Wholesale & retail | 2002 |
| Jayumiya Ltd | Wholesale & retail | 2025 |
| Jayvee Investments Limited | Real estate | 2021 |
| Jayveer International Limited | Wholesale & retail | 2025 |
| JAZ Chemical Pathologists Limited | Health & social care | 2002 |
| Jazz Panesar Ltd | Other services | 2013 |
| Jazz Skills Global Ltd | Education | 2014 |
| Jazzitup Kids Limited | Education | 2009 |
| JB Accommodations Limited | Real estate | 2015 |
| JB Construction Group Ltd | Professional & scientific | 2015 |
| JB Contractor Limited | Financial services | 2014 |
| JB Dwellings Ltd | Other services | 2023 |
| JB Foods & Meals Ltd | Hospitality | 2025 |
| JB General Building Services Ltd | Construction | 2016 |
| JB Kingsbury Ltd | Hospitality | 2025 |
| JB Metals UK Limited | Wholesale & retail | 2021 |
| JB Structures Ltd | Construction | 2009 |
| JB UK Construction Solutions Ltd | Construction | 2024 |
| JB Ultrasonics Limited | Construction | 2014 |
| JB Ventures Group Ltd | Information & communication | 2025 |
| JBA Investments Ltd | Real estate | 2012 |
| Jbcs & Associates Limited | Education | 2010 |
| JBG Construction Solutions Ltd | Manufacturing | 2025 |
| Jbkservices Limited | Wholesale & retail | 2024 |
| Jbnm Consulting Limited | Professional & scientific | 2014 |
| JBP Consulting Ltd | Professional & scientific | 2014 |
| JBP Foods Ltd | Wholesale & retail | 2017 |
| JBR Media Group Limited | Wholesale & retail | 2024 |
| Jburtonwalsh Ltd | Administrative & support | 2010 |
| JC Accounting & Finance Limited | Administrative & support | 2017 |
| JC Electrics 35 Limited | Construction | 2022 |
| JC Installs Limited | Construction | 2016 |
| JC Sport and Education Limited | Arts & recreation | 2022 |
| Jc&D Properties Limited | Construction | 2023 |
| JCA Handyman Limited | Other services | 2017 |
| Jcandle Ltd | Health & social care | 2024 |
| JCD Aviation Limited | Transport & logistics | 2024 |
| JCD Investments Limited | Real estate | 1995 |
| JCE Grove Limited | Real estate | 2024 |
| JCE Maninvest Limited | Administrative & support | 2008 |
| JCE New Road Limited | Real estate | 2021 |
| JCE RE Limited | Transport & logistics | 2019 |
| JCS IT Services Limited | Information & communication | 2014 |
| JCW Consultants Limited | Professional & scientific | 2013 |
| JD Accountants Ltd | Professional & scientific | 2010 |
| JD Beauty Warehouse Ltd | Wholesale & retail | 2024 |
| JD Capital Investments Limited | Real estate | 2017 |
| JD Developments Southern Limited | Construction | 2019 |
| JD Family Ltd | Real estate | 2024 |
| JD Freelance Chef Ltd | Hospitality | 2019 |
| JD Well Limited | Construction | 2013 |
| JD1 Construction Limited | Households | 2020 |
| JD4 Properties Ltd | Real estate | 2017 |
| Jdelux Ltd | Wholesale & retail | 2021 |
| JDG & Company Ltd. | Financial services | 2014 |
| JDK Inc Ltd | Wholesale & retail | 2025 |
| JDL World Ltd | Wholesale & retail | 2022 |
| JDN Enterprise Ltd | Information & communication | 2018 |
| Jdoneo Limited | Real estate | 2024 |
| Jdpd (London) Limited | Other services | 2019 |
| JDS Engineers Ltd | Professional & scientific | 2021 |
| Jdschool Ltd | Education | 2020 |
| JE CAD Specialist Ltd | Professional & scientific | 2018 |
| JEB Yards Ltd | Real estate | 2024 |
| JEC Mail Order Limited | Wholesale & retail | 2025 |
| Jec(London) Limited | Manufacturing | 2020 |
| JED Property Portfolio Limited | Real estate | 2016 |
| Jeder Ltd | Wholesale & retail | 2019 |
| Jedi Concepts Ltd | Information & communication | 2019 |
| JEE Services Ltd | Construction | 2026 |
| Jeedi Services Limited | Administrative & support | 2026 |
| Jeff Building Solutions Ltd | Construction | 2014 |
| Jeff Mcmanus Limited | Professional & scientific | 1987 |
| Jeff's Pickings Limited | Real estate | 2015 |
| Jefferson Saleh Ltd | Professional & scientific | 2023 |
| Jegnus UK Ltd | Administrative & support | 2021 |
| Jellyhead Ltd | Real estate | 2022 |
| Jelv Ltd | Construction | 2022 |
| Jembet Limited | Professional & scientific | 2010 |
| Jemroc Trading Services Limited | Health & social care | 2015 |
| Jemworth Marketing Limited | Administrative & support | 2007 |
| Jenda-Tech Ltd | Information & communication | 2014 |
| Jenny Wilde Associates Ltd | Administrative & support | 2008 |
| Jeroza Limited | Hospitality | 2024 |
| Jersey Rowe Solutions Ltd | Health & social care | 2024 |
| JES Builders Ltd | Manufacturing | 2026 |
| Jesani Limited | Professional & scientific | 2002 |
| Jesham Properties Limited | Real estate | 2015 |
| Jess Flowers Limited | Wholesale & retail | 2018 |
| Jesseys Confectioners Limited | Wholesale & retail | 2024 |