| Jordan Payne Socials Ltd | Professional & scientific | 2024 |
| Jory Group Limited | Construction | 2020 |
| Josef Sykora Limited | Education | 2019 |
| Josef Wealth Management Limited | Professional & scientific | 2022 |
| Joseph Rufino Cordeiro Foundation Ltd | Education | 2022 |
| Joseys Care Ltd | Hospitality | 2025 |
| Joshua Lumley Limited | Wholesale & retail | 2009 |
| Josia Group Ltd | Administrative & support | 2019 |
| Joso Contracting Limited | Construction | 2024 |
| Joy and Co Design and Build Limited | Construction | 2025 |
| Joy Entertainment Ltd | Administrative & support | 2012 |
| JP Flynn Property Management Ltd | Real estate | 2017 |
| JP MCD Ltd | Professional & scientific | 2015 |
| JP Properties & Design Ltd | Real estate | 2000 |
| JP Rail Ltd | Construction | 2023 |
| JPA Designs Limited | Construction | 2020 |
| JPD Architecture UK Limited | Professional & scientific | 2009 |
| JPH Contractors Ltd | Construction | 2019 |
| JPJ Builders Ltd | Construction | 2015 |
| JPR Consulting Services Limited | Professional & scientific | 2015 |
| Jpra Limited | Hospitality | 2017 |
| Jpsons Limited | Other services | 2017 |
| JPW Europe Ltd | Professional & scientific | 2015 |
| JR Gilbert Engineering Solutions Ltd | Construction | 2014 |
| JR Operators Limited | Construction | 2020 |
| JR Site Solutions Ltd | Wholesale & retail | 2024 |
| JR Verticals Ltd | Information & communication | 2017 |
| JR Wealth Management Ltd | Financial services | 2022 |
| JRB Engineering Limited | Professional & scientific | 2019 |
| JRF (Kent) Consultants Ltd | Professional & scientific | 2016 |
| JRJ Allen Engineering Limited | Professional & scientific | 2021 |
| JRK Electrical Services Ltd | Construction | 2019 |
| JRS Exterior Cleaning Ltd | Administrative & support | 2026 |
| JRT Capital Limited | Professional & scientific | 2021 |
| JRW Financial Consulting Ltd | Professional & scientific | 2025 |
| JS IT Limited | Information & communication | 2019 |
| JS Wadeson Holdings Ltd | Administrative & support | 2019 |
| JSB Consultancy Services Limited | Professional & scientific | 2025 |
| Jsbj Properties Ltd | Real estate | 2015 |
| JSC Cooke Construction Limited | Construction | 2009 |
| JSC Decorating Ltd | Construction | 2023 |
| Jsms IT Ltd | Information & communication | 2020 |
| JSP Building Solutions Ltd | Construction | 2026 |
| JSP Pump Maintenance Limited | Professional & scientific | 2008 |
| JSS Consulting Limited | Administrative & support | 2024 |
| JT Agents Ltd | Real estate | 2023 |
| JT and Partners Limited | Administrative & support | 2015 |
| JT Contracting Services Limited | Construction | 2023 |
| JT Heating & Plumbing Limited | Construction | 2020 |
| JT Kitchens & Bathrooms Ltd | Construction | 2024 |
| JTA Carpentry Ltd | Manufacturing | 2026 |
| JTB Developers Ltd | Real estate | 2019 |
| Jtnc Construction Ltd | Construction | 2021 |
| JTO Signalling Ltd | Construction | 2023 |
| JTP Plant Limited | Administrative & support | 2025 |
| JTS Furnitures Hub Limited | Wholesale & retail | 2025 |
| JTT Tiling Ltd | Construction | 2026 |
| Jude Consulting Limited | Professional & scientific | 2012 |
| Judge Architects Ltd | Professional & scientific | 2012 |
| Juice Financial Ltd | Financial services | 2019 |
| Juke U.K &SON Ltd | Real estate | 2012 |
| Julie Benfield Limited | Administrative & support | 2017 |
| Juloon Services Ltd | Construction | 2022 |
| Jurmax Limited | Professional & scientific | 2024 |
| Jusmax Trading Ltd | Administrative & support | 2016 |
| Just Accountancy & Tax Advice Ltd | Professional & scientific | 2020 |
| Just Drive Leasing Limited | Financial services | 2024 |
| Just FM Consulting Ltd | Professional & scientific | 2024 |
| Just Groomed Limited | Other services | 2022 |
| Just Heat Pumps Limited | Construction | 2025 |
| Just Welfare Holdings Limited | Financial services | 2024 |
| Just Welfare Limited | Administrative & support | 2013 |
| Justine Cullen Ltd | Wholesale & retail | 2017 |
| Justphils Limited | Mining & quarrying | 2024 |
| JV Consultancy Services Ltd | Professional & scientific | 2025 |
| JV Property Services Limited | Real estate | 2007 |
| JW Beach Transport Limited | Transport & logistics | 2025 |
| JW Digital Limited | Information & communication | 2009 |
| Jwbm Group Ltd | Water & waste | 2017 |
| Jwbm Holdings Limited | Extraterritorial | 2019 |
| Jwhs Services Limited | Construction | 2017 |
| JY Advisory Ltd | Professional & scientific | 2019 |
| JYC Venture Ltd | Professional & scientific | 2024 |
| JZM Consultancy Ltd | Information & communication | 2022 |
| K & G Hairdressing Supplies Ltd | Other services | 2000 |
| K & J Poundhouses Ltd | Real estate | 2024 |
| K & M Developments Limited | Construction | 2017 |
| K - Factor Ltd | Information & communication | 2004 |
| K and L Hair Design Limited | Other services | 2025 |
| K and L Wines and Spirits UK Ltd | Wholesale & retail | 2007 |
| K C S (Ashford) LLP | | 2012 |
| K D Cable Jointing Ltd | Construction | 2016 |
| K Gosling Construction Ltd | Construction | 2020 |
| K Heer Consulting Ltd | Information & communication | 2025 |
| K Kirthi Limited | Health & social care | 2008 |
| K P W Electrical Limited | Construction | 2007 |
| K Piotrowski Limited | Professional & scientific | 2017 |
| K Spray Limited | Professional & scientific | 2013 |
| K Star Properties Limited | Real estate | 2022 |
| K Stocks Ltd | Wholesale & retail | 2020 |