| John Glover Plumbing & Heating Ltd | Construction | 2007 |
| John H Hunt Limited | Professional & scientific | 2015 |
| John Luca Properties Limited | Real estate | 2024 |
| John Percy Developments Ltd | Construction | 2019 |
| John Snape Motors Limited | Wholesale & retail | 2003 |
| John W Pettet Associates Limited | Professional & scientific | 2003 |
| John Watson Design & Communications Limited | Other services | 2005 |
| Johnson Floyd Building Services Limited | Construction | 2005 |
| Johnston Plant Sales Limited | Wholesale & retail | 2010 |
| JOI Consulting Solutions Limited | Professional & scientific | 2021 |
| Jointing Services Limited | Construction | 2001 |
| Jointly Marketing Ltd | Professional & scientific | 2021 |
| Joks Build Limited | Construction | 2018 |
| Jolit Support Services Ltd | Health & social care | 2026 |
| Joll Associates Ltd | Financial services | 2025 |
| Jollymiller Ltd | Wholesale & retail | 2018 |
| Jollymiller One Ltd | Wholesale & retail | 2019 |
| JON Fallowell Classics Ltd | Wholesale & retail | 2026 |
| JON LEE Financial Services Limited | Financial services | 2007 |
| Jonathan Malcolm Limited | Information & communication | 2013 |
| Jones Property Investments Limited | Real estate | 2012 |
| Jongia (UK) Limited | Wholesale & retail | 2003 |
| Jongman Video Editing Ltd | Information & communication | 2016 |
| Joni’S Trading Limited | Wholesale & retail | 2024 |
| Joon Creatrix Limited | Hospitality | 2024 |
| Joseph ASH Limited | Manufacturing | 1919 |
| Joseph James Property Ltd | Real estate | 2021 |
| Joseph Lucas Limited | Extraterritorial | 1907 |
| Josephine Faal Books Ltd | Information & communication | 2024 |
| Josh Muir Building Services Ltd | Construction | 2022 |
| Joulecomm Ltd | Information & communication | 2020 |
| Journey the World Limited | Administrative & support | 1997 |
| Joyce Construction Group Ltd | Construction | 2021 |
| Joyeux Solution Limited | Wholesale & retail | 2025 |
| Joyful Gift Ltd | Wholesale & retail | 2024 |
| JP Education and Training Ltd | Education | 2016 |
| JP Engineering Ltd | Administrative & support | 2024 |
| JP Finance Solutions Limited | Professional & scientific | 2017 |
| JP Intentional Ltd | Other services | 2024 |
| JP Techsolutions Limited | Administrative & support | 2014 |
| Jpack Ltd | Administrative & support | 2016 |
| Jpeg Morgan Limited | Professional & scientific | 2022 |
| JPK Railway Signalling Limited | Professional & scientific | 2013 |
| JPM Property Ltd | Real estate | 2022 |
| JPN Property Solutions Ltd | Real estate | 2013 |
| Jpred Limited | Hospitality | 2019 |
| JPS Doors Limited | Construction | 2021 |
| JR Seafood Ltd | Hospitality | 2026 |
| JR Surulere Limited | Wholesale & retail | 2024 |
| Jrais Car Group Ltd | Wholesale & retail | 2013 |
| Jrais Holdings Ltd | Real estate | 2019 |
| Jrbcc Ltd | Real estate | 2017 |
| Jrcc Automotive Ltd | Administrative & support | 2026 |
| Jrnp Ltd | Construction | 2016 |
| JRP Contractors Limited | Construction | 2006 |
| Jrtech Solutions Limited | Information & communication | 2012 |
| JS Business Support Ltd | Professional & scientific | 2026 |
| JS Fulford Consultancy Limited | Professional & scientific | 2026 |
| JS Maiden Consultancy Services Limited | Financial services | 2014 |
| JS Morris Electrical Ltd | Construction | 2019 |
| JS Transport Limited | Transport & logistics | 2007 |
| Jsabin Ltd | Health & social care | 2022 |
| JSB Sports Ltd | Information & communication | 2026 |
| JSC Plant Labour Ltd | Construction | 2020 |
| JSM Heating Limited | Construction | 2011 |
| JSM Rings Limited | Wholesale & retail | 2005 |
| Jsmeraki Consulting Limited | Professional & scientific | 2021 |
| JSP Wealth Management Limited | Professional & scientific | 2025 |
| JSU Consulting Ltd | Professional & scientific | 2016 |
| Jswh Management Ltd | Administrative & support | 2009 |
| JT Accounting Services Ltd | Professional & scientific | 2023 |
| JT Valeting and Cleaning Limited | Other services | 2015 |
| Jt&S Property Developments Limited | Construction | 2022 |
| JTD Asset Solutions Limited | Wholesale & retail | 2008 |
| JTG Installations Ltd | Administrative & support | 2017 |
| JTK Consultancy Ltd | Construction | 2025 |
| Jubilee Church Solihull | Other services | 2014 |
| Jubilee Consultation Services Ltd | Construction | 2026 |
| Jubilee Dental Ceramics Limited | Health & social care | 2015 |
| Jubilee Fire Services Ltd | Health & social care | 2024 |
| Jublee Motors Ltd | Wholesale & retail | 2026 |
| Jucarta Property Development Group Ltd | Real estate | 2025 |
| Judges Real Brewery Limited | Professional & scientific | 1999 |
| Juel Business Services Limited | Wholesale & retail | 1980 |
| Juice Creative Studios Ltd | Professional & scientific | 2024 |
| Juliannas Cattery Limited | Other services | 2006 |
| Juliannas Kennels Limited | Hospitality | 2013 |
| Jumar Solutions Limited | Information & communication | 2025 |
| Jumar Technology Limited | Information & communication | 2025 |
| June Energy UK Ltd | Administrative & support | 2020 |
| Jungle Lifeline CIC | Education | 2025 |
| Jungle Ranger Experiences Ltd | Administrative & support | 2026 |
| Jupiter Building Consultancy Ltd | Construction | 2023 |
| JUS Gana Create Ltd | Arts & recreation | 2020 |
| Just Buildz Ltd | Construction | 2022 |
| Just Checking Future Ltd | Financial services | 2024 |
| Just Checking Holdings Limited | Financial services | 2013 |
| Just Checking Ltd | Manufacturing | 2003 |
| Just Fitted Kitchens Surrey Ltd | Wholesale & retail | 2015 |
| Just Furnishings Limited | Wholesale & retail | 2006 |