| JCL Transport Group Ltd | Transport & logistics | 2018 |
| JCS Commissioning Services Limited | Professional & scientific | 2002 |
| JD Mills Engineering Limited | Manufacturing | 2017 |
| JDW Tools and Fixings Ltd | Wholesale & retail | 2024 |
| Jedi Investments Ltd | Administrative & support | 2011 |
| Jeffin Limited | Professional & scientific | 2026 |
| Jenner (Contractors) Limited | Manufacturing | 2008 |
| Jenner Group Limited | Construction | 2014 |
| Jenner Holdco Limited | Financial services | 2025 |
| Jennings Kendall Limited | Wholesale & retail | 2024 |
| Jenny and the Machines Ltd | Manufacturing | 2024 |
| JES Trading Ltd | Wholesale & retail | 2024 |
| Jfko Holdings Ltd | Financial services | 2023 |
| JGI International Limited | Information & communication | 2016 |
| JH Estates Investment Limited | Real estate | 2023 |
| JHE Thompson Limited | Professional & scientific | 2013 |
| Jhon Quickfix Ltd | Administrative & support | 2024 |
| JHS Kent Ltd | Wholesale & retail | 2023 |
| JIB Cooling Limited | Construction | 2022 |
| JIM Garrahy's Fudge Kitchen Limited | Manufacturing | 1983 |
| Jimie's Chop Shop Ltd | Other services | 2024 |
| Jimjam Arts | Arts & recreation | 2015 |
| JJ Electrical Contracting Ltd | Construction | 2021 |
| JJ Property Kent Ltd | Real estate | 2020 |
| JK Travel Solutions Ltd | Wholesale & retail | 2023 |
| JLC Financial Ltd | Real estate | 2021 |
| JLH Arts Agency Ltd | Arts & recreation | 2021 |
| JM Rail Engineers Ltd | Construction | 2017 |
| JMS Finishes Ltd | Arts & recreation | 2025 |
| JMW Data Solutions Limited | Professional & scientific | 2022 |
| JNJ Thirteen Limited | Construction | 2019 |
| Joanne Clark Business & Financial Services Ltd | Professional & scientific | 2016 |
| Joanne K Williams Ltd | Arts & recreation | 2022 |
| Joburg Bites Ltd | Wholesale & retail | 2025 |
| JOE O’Grady Carpentry Ltd | Manufacturing | 2018 |
| JOE Thomas Asbestos Surveying Limited | Financial services | 2022 |
| John Crofts Productions Ltd | Professional & scientific | 2014 |
| John Dory Wine Limited | Hospitality | 2022 |
| Johnsons Recycling Limited | Water & waste | 2003 |
| Jointon Mews Management Limited | Households | 2019 |
| Jomlies Ltd | Hospitality | 2019 |
| JON Sparks Leadership Consultancy Limited | Professional & scientific | 2023 |
| Jonathan Burlow Limited | Professional & scientific | 2019 |
| Jonesbuild Contractors Ltd | Construction | 2022 |
| Jordan Button Roofing Ltd | Construction | 2026 |
| Jordan Property Solutions Ltd | Real estate | 2025 |
| Josephine Dessine CM Ltd | Wholesale & retail | 2021 |
| Joshua Alexander Ventures Limited | Professional & scientific | 2019 |
| Joyce Division Limited | Information & communication | 2014 |
| JP and Sons Groundworks Ltd | Construction | 2026 |
| JP Autos Ltd | Wholesale & retail | 2026 |
| JP Foods Ltd | Hospitality | 2026 |
| JP Plumbing Kent Limited | Construction | 2026 |
| JPC Asset Management Ltd | Wholesale & retail | 2011 |
| JPG Indra Limited | Hospitality | 2022 |
| JR Homeware Ltd | Wholesale & retail | 2022 |
| JRB Carpentry & Construction Limited | Construction | 2018 |
| JSM Renovations Ltd | Construction | 2023 |
| JSN Distributors Ltd | Wholesale & retail | 2024 |
| JT Construction & Utilities Ltd | Construction | 2024 |
| JT Sportz | | 2004 |
| Judd Folly Hotel Services Limited | Hospitality | 2019 |
| Julian Estates Limited | Real estate | 1986 |
| Julian Road Ltd | Construction | 2021 |
| Jungle and Savannah Ltd | Administrative & support | 2025 |
| Juno Beauty and Aesthetics Ltd | Other services | 2020 |
| Just Delegate Ltd | Professional & scientific | 2010 |
| Justanother Architect Limited | Professional & scientific | 2022 |
| JV Architects Ltd | Professional & scientific | 2015 |
| JW Fire Door Inspection Ltd | Professional & scientific | 2025 |
| JW Surveys Limited | Professional & scientific | 2012 |
| JW UK Design Limited | Wholesale & retail | 2025 |
| JWC Interiors Ltd | Construction | 2017 |
| Jwcy Consulting Ltd | Wholesale & retail | 2023 |
| JWO Solutions Limited | Administrative & support | 2015 |
| JWW Holdings Limited | Information & communication | 2018 |
| K a a Electrical Contractors Limited | Construction | 2009 |
| K&N Signs Ltd | Manufacturing | 2016 |
| Kaarthic & Pranavi Ltd | Wholesale & retail | 2024 |
| Kabul Pizza Ltd | Hospitality | 2026 |
| Kaichen Ltd | Professional & scientific | 2022 |
| Kaleidoscope Communications Ltd | Information & communication | 2014 |
| Kaleidoscope Music Group Ltd | Information & communication | 2024 |
| KAM Plastering Contractors Limited | Construction | 2006 |
| Kampari Style Limited | Manufacturing | 2025 |
| Kara Partners Ltd | Information & communication | 2016 |
| Kara Shop Ltd | Wholesale & retail | 2024 |
| Karman Group Ltd | Wholesale & retail | 2024 |
| Kaski Design Ltd | Manufacturing | 2019 |
| Kat-Design Ltd | Professional & scientific | 2017 |
| Kawa Management Services Ltd | Professional & scientific | 2017 |
| Kay-Kuna Ltd | Wholesale & retail | 2024 |
| KBC Global Consulting Limited | Administrative & support | 2025 |
| KBS Media Ltd | Information & communication | 2023 |
| KCA Towbars & Trailers Limited | Wholesale & retail | 2023 |
| KCH Consortium UK Limited | Financial services | 2024 |
| KCM Digital Limited | Information & communication | 2022 |
| KE4BUSINESS Limited | Professional & scientific | 2005 |
| Kebab Holding Ltd | Hospitality | 2025 |
| Keeling Property Investments Limited | Real estate | 2013 |