| JDS Carpets Ltd | Construction | 2016 |
| Je&A Enterprises Ltd | Real estate | 2022 |
| Jeca Properties Limited | Real estate | 2012 |
| Jedstar Limited | Manufacturing | 2024 |
| Jefferson Flogas Limited | Wholesale & retail | 2026 |
| JEG Access Inspection Solutions Ltd | Other services | 2025 |
| JEM Access Services Ltd | Construction | 2024 |
| Jenas Property Limited | Real estate | 2019 |
| Jenkins Digital Services Limited | Information & communication | 2017 |
| Jennifer Owens Ltd | Information & communication | 2021 |
| Jennifer, Moses and Partners Limited | Health & social care | 2025 |
| Jenon Accessories Ltd | Wholesale & retail | 2023 |
| Jenuine Styles Ltd | Other services | 2012 |
| Jessie and James Limited | Wholesale & retail | 2010 |
| Jetbell Contractors Limited | Professional & scientific | 2015 |
| Jewu Tech Limited | Information & communication | 2024 |
| Jflorence Narrative Limited | Wholesale & retail | 2026 |
| JFW Engineering Services Ltd | Professional & scientific | 2023 |
| JGB Exterior Cleaning Ltd | Administrative & support | 2024 |
| JGM Executives Limited | Professional & scientific | 2024 |
| JGS Property Group Ltd | Real estate | 2015 |
| JH Roofing Ltd | Construction | 2021 |
| JH Tree Services Hampshire Ltd | Agriculture & fishing | 2022 |
| JHOLDEN26 Ltd | Education | 2025 |
| Jhtk Limited | Extraterritorial | 2019 |
| Jiga Property Limited | Real estate | 2025 |
| Jigi Estates Ltd | Real estate | 2026 |
| Jiig Developments Limited | Construction | 2018 |
| Jijk Limited | Professional & scientific | 2010 |
| JIM Stokes Workshops Holdings Limited | Professional & scientific | 2009 |
| JIM Stokes Workshops Limited | Wholesale & retail | 1993 |
| Jiva Materials Ltd | Manufacturing | 2017 |
| JJ Bundles Limited | Wholesale & retail | 2021 |
| JJ Shop Limited | Wholesale & retail | 2025 |
| Jjamm Holdings Limited | Real estate | 2016 |
| Jjcs Construction Services Limited | Construction | 2021 |
| Jjctraining Ltd | Arts & recreation | 2014 |
| Jjfm Group Ltd | Administrative & support | 1997 |
| JJW Consultants Ltd | Information & communication | 2025 |
| JK Home Improvements Limited | Construction | 2013 |
| JK Kingdom Solution Ltd | Professional & scientific | 2022 |
| JK Property Lettings Limited | Real estate | 2019 |
| Jk&K Limited | Professional & scientific | 1996 |
| Jkdl Limited | Professional & scientific | 2020 |
| Jkgr Holdings Limited | Financial services | 2023 |
| JKN Safety Compliance Ltd | Professional & scientific | 2024 |
| JL Events Sussex Limited | Hospitality | 2025 |
| JL Vegan Delights Ltd | Hospitality | 2020 |
| JLE Rail Ltd | Transport & logistics | 2016 |
| JLI Contractors Limited | Construction | 2020 |
| JLR Facilities Ltd | Manufacturing | 2015 |
| JLR Group Ltd | Construction | 2019 |
| JLR Services Southern Ltd | Construction | 2012 |
| JLR Solar UK Ltd | Construction | 2017 |
| Jlrw Ltd | Professional & scientific | 2021 |
| Jlsta Engineering Ltd | Professional & scientific | 2019 |
| JM Ralph Ltd | Professional & scientific | 2021 |
| JM Security Services Ltd | Administrative & support | 2021 |
| Jmbpc Ltd | Other services | 2014 |
| JMC Decorating and Refurbishment Limited | Construction | 2025 |
| JN Security & Medical Services Ltd | Administrative & support | 2026 |
| JNB Healthcare Limited | Health & social care | 2019 |
| JNG Planning Limited | Professional & scientific | 2019 |
| Joanna Jones Management Ltd | Arts & recreation | 2013 |
| Jodie Real Estate Ltd | Real estate | 2025 |
| Jody Long Ltd | Professional & scientific | 2023 |
| JOE Palmer Flooring Specialist Ltd | Construction | 2024 |
| John Chapman Coaching Limited | Professional & scientific | 2024 |
| John Lumsden Donaldson Spain Ltd | Wholesale & retail | 2021 |
| John R Murch Roofing Limited | Construction | 2019 |
| John Rothery (Wholesale) Company Limited | Wholesale & retail | 1971 |
| John Rothery and Company Limited | Professional & scientific | 1971 |
| John Simmance Limited | Wholesale & retail | 2008 |
| Johnny S Photography Limited | Professional & scientific | 2017 |
| Johnson Controls Building Efficiency UK Limited | Construction | 2014 |
| Johnson Controls China Investment (UK) Limited | Financial services | 2017 |
| Johnson Controls Commercial UK Ltd | Professional & scientific | 2014 |
| Johnson Controls Enterprises Ltd | Professional & scientific | 1999 |
| Johnson Controls Holding UK Ltd | Professional & scientific | 2015 |
| Johnson Controls International Holdings Ltd | Professional & scientific | 2015 |
| Johnson Controls Investments (UK) Limited | Professional & scientific | 2000 |
| Johnson Controls Metal Components Birmingham Limited | Professional & scientific | 1997 |
| Johnson Controls Qatar Holding (UK) Ltd. | Professional & scientific | 2016 |
| Johnson Controls Systems Development Limited | Information & communication | 2013 |
| Johnson Controls UAE Holding Ltd. | Professional & scientific | 2016 |
| Johnson's Enterprises Limited | Wholesale & retail | 2000 |
| Johnsons Property and Homes Ltd | Real estate | 2024 |
| Johnston Wood Roach Holdings Limited | Financial services | 2019 |
| Johnston Wood Roach Limited | Other services | 1998 |
| Join Tribe Limited | Other services | 2022 |
| Joinery Finish Solutions Limited | Manufacturing | 2024 |
| Joinery Solutions Southern Ltd | Manufacturing | 2011 |
| Jojo Fitness Limited | Arts & recreation | 2019 |
| Jojo Pet Co Ltd | Manufacturing | 2025 |
| Jokg Ltd | Information & communication | 2014 |
| Jolkickz Limited | Wholesale & retail | 2025 |
| Jolly Jellies Ltd | Wholesale & retail | 2024 |
| JON Madden Media Ltd | Information & communication | 2021 |
| JON Taylor Electrical Services Limited | Manufacturing | 2025 |
| Jones and Carvill Ltd | Education | 2021 |