| JNG Services Ltd | Construction | 2024 |
| JNN Accountants Limited | Professional & scientific | 2014 |
| JNO Estates Limited | Real estate | 2020 |
| JNO Holding Ltd | Financial services | 2026 |
| JNW Electrical Ltd | Construction | 2019 |
| JOE Logs Tree Services Ltd | Administrative & support | 2025 |
| JOE White Solutions Limited | Manufacturing | 2016 |
| Johann Havenga Ltd | Health & social care | 2018 |
| John Bedford Entertainments Limited | Arts & recreation | 2006 |
| John Clark Fabrications Limited | Administrative & support | 2014 |
| John Cummings Wealth Management Ltd | Financial services | 2014 |
| John Palmer Carpets Limited | Wholesale & retail | 1995 |
| John Peck Construction Ltd | Construction | 2001 |
| Johnson Holdco 1 Limited | Real estate | 2020 |
| Johnson Holdco 2 Limited | Real estate | 2020 |
| Johnson Holdco 3 Limited | Real estate | 2020 |
| Johnstone Specsavers Limited | Wholesale & retail | 2024 |
| Joinery Estimating Services Limited | Construction | 2018 |
| Jolly Roger PUB Ltd | Hospitality | 2018 |
| JON Day Photography Limited | Real estate | 2014 |
| JON Willis Ltd | Construction | 2017 |
| Jonathan Charles Residential Ltd | Real estate | 2026 |
| Jones Autofinish Ltd | Wholesale & retail | 2025 |
| Jones Investment Holdings Limited | Financial services | 2020 |
| Jones Yacht Construction Ltd | Manufacturing | 2023 |
| Jong Games Ltd | Information & communication | 2024 |
| Jonny Gouldstone Photography Ltd | Professional & scientific | 2025 |
| Jont Limited | Professional & scientific | 2012 |
| Jordan Capital Holdings Limited | Real estate | 2025 |
| Jordan Carpentry and Building Limited | Construction | 2020 |
| Joseph Arthur Kensington Limited | Real estate | 2024 |
| Joseph Arthur Limited | Financial services | 2018 |
| Joseph Arthur Trading Limited | Construction | 2020 |
| Joseph James Painting and Decorating Ltd | Construction | 2026 |
| Josh Gabbitas Ltd | Professional & scientific | 2025 |
| Joshua Haynes Heating & Plumbing Services Limited | Construction | 2022 |
| Journey Events Ltd | Manufacturing | 2004 |
| JP Capital Partners Limited | Energy | 2012 |
| JP Marine Consultants Limited | Transport & logistics | 2005 |
| JP Progressive Social Work Ltd | Health & social care | 2021 |
| JP Young Heating Limited | Other services | 2021 |
| JPE Acquisition Limited | Financial services | 2025 |
| JPS Autocare (South) Limited | Wholesale & retail | 2023 |
| JR Distribution Hub Ltd | Wholesale & retail | 2025 |
| JR Goose Consulting Ltd | Construction | 2017 |
| JR2ELECTRICAL Ltd | Construction | 2024 |
| JRB Plant Limited | Administrative & support | 2021 |
| JRC Services ( Hampshire ) Ltd | Other services | 2017 |
| JRE Consultancy Limited | Construction | 2016 |
| JRH Commercials Limited | Water & waste | 2014 |
| JRS Decorating Ltd | Construction | 2016 |
| JS Accounting Consultant Limited | Professional & scientific | 2020 |
| JS Legal Solutions Ltd | Professional & scientific | 2025 |
| JS Letting Agent Limited | Households | 2022 |
| JS Prime Limited | Transport & logistics | 2017 |
| Jsadki SHO Limited | Wholesale & retail | 2025 |
| JSG Management & Constructive Solutions Ltd | Construction | 2016 |
| JSG Property Holdings Ltd | Real estate | 2024 |
| JSJ Landscaping Ltd | Construction | 2020 |
| JSM Stands Ltd | Professional & scientific | 2022 |
| JSP Digital Ltd | Wholesale & retail | 2026 |
| JT (Global) Limited | Information & communication | 2010 |
| JT International Vehicle Exports Ltd | Wholesale & retail | 2014 |
| JTC and Sons Ltd | Health & social care | 2014 |
| JTH Technical Services Ltd | Administrative & support | 2018 |
| JTL Cars Limited | Wholesale & retail | 2023 |
| Jubilee Joinery Limited | Manufacturing | 2008 |
| Juckes Property Services Ltd | Real estate | 2024 |
| Juggle Outsourcing Limited | Administrative & support | 2018 |
| Julie Bloxsome Ltd | Administrative & support | 2024 |
| Jumpingstone Limited | Professional & scientific | 2000 |
| Jungle Buddies Limited | Hospitality | 2011 |
| Juniper Investco Limited | Real estate | 2024 |
| Juniper Jvco Limited | Real estate | 2024 |
| Juniper Propco (Bourn) Limited | Real estate | 2024 |
| Juno Products Ltd | Wholesale & retail | 2023 |
| Jupiter Future Ltd | Wholesale & retail | 2018 |
| Jupiter Neptune Ventures Ltd | Wholesale & retail | 2024 |
| Jurassic Estates Limited | Real estate | 2016 |
| Just About Strength Limited | Other services | 2017 |
| Just Petz Ltd | Wholesale & retail | 2024 |
| Just Provence Limited | Administrative & support | 2008 |
| Just Valves Limited | Manufacturing | 2024 |
| Justina Gunina Designs Limited | Professional & scientific | 2025 |
| JVR Construction Ltd | Professional & scientific | 2015 |
| JVW Developments Ltd | Real estate | 2026 |
| JW Developments (Cotswold) Ltd | Real estate | 2008 |
| JW Speciality Ltd | Hospitality | 2014 |
| JWR Home Innovations Ltd | Construction | 2024 |
| K & a Properties (Southern) Ltd | Real estate | 2021 |
| K & B Crushers Ltd | Extraterritorial | 1995 |
| K & E Family Holdings Ltd | Financial services | 2023 |
| K & J Waste Management Services Limited | Extraterritorial | 2009 |
| K Dania Limited | Health & social care | 2018 |
| K KEL Solutions Ltd | Construction | 2025 |
| K Nuttall Carpets & Flooring Limited | Construction | 2019 |
| K R Strugnell Limited | Administrative & support | 2006 |
| K W Lawrence Builders Ltd | Construction | 2019 |
| K&K Itglobal Ltd | Other services | 2009 |
| K&L Cleans LLP | | 2026 |