| J P Parker Holdings Limited | Financial services | 2025 |
| J P S Contracts Limited | Construction | 2006 |
| J S Drilling Services Limited | Construction | 2009 |
| J SEV Ltd | Administrative & support | 2023 |
| J-Flex Rubber Products Ltd. | Extraterritorial | 1998 |
| J. B. Kidney (Lettings) Limited | Real estate | 2011 |
| J. B. Kidney Limited | Real estate | 2007 |
| J. M. Baguley Limited | Financial services | 2010 |
| J.Bradshaw & Sons Limited | Transport & logistics | 1964 |
| J.F.C. Investments Limited | Real estate | 2000 |
| Jack Smith Holdings Ltd | Financial services | 2024 |
| Jack Smith Properties Limited | Real estate | 1994 |
| Jackson & Clayton Ltd | Wholesale & retail | 2023 |
| Jackson & Jackson Ltd | Other services | 2018 |
| Jacques Aesthetics Limited | Health & social care | 2019 |
| Jake Elliott Equestrian Limited | Agriculture & fishing | 2014 |
| Jamco Distributors Ltd | Financial services | 2024 |
| James Alexander Landscapes Ltd | Construction | 2023 |
| James Holiday Parks Limited | Hospitality | 2020 |
| James Parks Limited | Hospitality | 2014 |
| Jamesdean Solutions Limited | Wholesale & retail | 2020 |
| Jantim Limited | Real estate | 1981 |
| JAY Michael Ltd | Wholesale & retail | 2025 |
| JB Golf Supplies Ltd | Wholesale & retail | 2026 |
| JBR Construction Ltd | Manufacturing | 2026 |
| JBS Estates LLP | | 2023 |
| Jbs-Helicopters Ltd | Transport & logistics | 2020 |
| Jc's Auto Clinic Ltd | Wholesale & retail | 2024 |
| JCA Ternium Ltd | Households | 2021 |
| JCM Solutions Ltd | Administrative & support | 2025 |
| JD Care Group Ltd | Health & social care | 2025 |
| JD Consulting Engineers Limited | Manufacturing | 2011 |
| JD Environmental Solutions Limited | Professional & scientific | 2026 |
| JD Loophole Limited | Wholesale & retail | 2025 |
| Jdhhc Limited | Other services | 2018 |
| JDL Driving Limited | Education | 2025 |
| JE Sports Horses Limited | Agriculture & fishing | 2024 |
| Jeanilious@ the Coffee Terrace Ltd | Hospitality | 2025 |
| Jeatonbjj Limited | Arts & recreation | 2025 |
| JEN and IAN Ltd | Administrative & support | 2014 |
| Jessop Park Limited | Real estate | 2020 |
| Jest Holdings Ltd | Real estate | 2026 |
| Jewel Safe Limited | Construction | 2018 |
| JFH Precision Limited | Manufacturing | 2025 |
| JHB H&S Services Ltd | Construction | 2023 |
| Jigsaw Insurance Services Limited | Professional & scientific | 2004 |
| Jimmy Products UK Limited | Manufacturing | 2020 |
| JJR Stokes Limited | Hospitality | 2022 |
| JLW Eco Surveys Ltd | Professional & scientific | 2025 |
| JMM & Sons Limited | Agriculture & fishing | 2022 |
| JMS Property Solutions Limited | Professional & scientific | 2014 |
| JMS Web Design Limited | Extraterritorial | 2012 |
| JND Technologies Limited | Manufacturing | 1990 |
| JND Wefco Limited | Professional & scientific | 1998 |
| John Carlill Holiday Lets Ltd | Hospitality | 2017 |
| John Edgar Agricultural Services Limited | Agriculture & fishing | 2016 |
| John Hamnett Limited | Financial services | 2019 |
| John Strawson Agriculture Ltd | Extraterritorial | 2017 |
| Johnathan Fagan Ltd | Energy | 2013 |
| Jomac Events Ltd | Hospitality | 2024 |
| Jones Drury Holdings Limited | Financial services | 2021 |
| Jones Solicitors LLP | | 2013 |
| Joolz Felix Ltd | Arts & recreation | 2020 |
| Joseph Camm Farms Limited | Agriculture & fishing | 1962 |
| Josh Shinner Photography Ltd | Professional & scientific | 2019 |
| Jowett Homes Limited | Real estate | 1978 |
| Joy Full Days Groupcare Limited | Health & social care | 2017 |
| JPS Racing Limited | Education | 2022 |
| JR Steel Solutions Ltd | Manufacturing | 2024 |
| JRA Safety Ltd | Extraterritorial | 2024 |
| JRB Construction Services Ltd | Administrative & support | 2017 |
| JRB Welding & Fabrication Co. Ltd | Manufacturing | 2007 |
| JRC Plumbing Ltd | Construction | 2018 |
| JS Homes Limited | Construction | 2017 |
| JS Joinery & Sons Ltd | Administrative & support | 2017 |
| JSR Security & Risk Management Ltd | Professional & scientific | 2025 |
| JTB Solutions Ltd | Professional & scientific | 2018 |
| Judge Electrical Solutions Ltd | Construction | 2019 |
| Juicy Design Limited | Professional & scientific | 2009 |
| Jumpsky Ltd | Professional & scientific | 2020 |
| Just BE More Ltd | Other services | 2017 |
| Just Cards Direct Limited | Wholesale & retail | 2007 |
| Just Incase Wines Ltd | Wholesale & retail | 2018 |
| JWR Joinery Limited | Construction | 2016 |
| JWR Renovations Limited | Construction | 2023 |
| K & R Home Improvements Ltd | Construction | 2025 |
| K Bottley Ltd | Information & communication | 2019 |
| K Hall Plumbing and Heating Ltd | Construction | 2016 |
| K-Islands Limited | Wholesale & retail | 2025 |
| K.N.L. Logistics Limited | Wholesale & retail | 2008 |
| Kairos Martial Arts CIC | Arts & recreation | 2021 |
| Kaleidoscope Consultants Limited | Professional & scientific | 2001 |
| Kaleidoscope International Limited | Professional & scientific | 2023 |
| KAM Market Ltd | Wholesale & retail | 2026 |
| Kara's Kitchen ST Limited | Wholesale & retail | 2020 |
| Karamick Ltd | Transport & logistics | 2018 |
| Karl White Vehicle Trading Limited | Transport & logistics | 2019 |
| Karlee Rooms Limited | Hospitality | 2019 |
| Karma Creation Ltd | Professional & scientific | 2024 |
| Karme Ltd | Professional & scientific | 2026 |