| JEK Education Consultancy Limited | Education | 2012 |
| Jekat Limited | Manufacturing | 2014 |
| Jeld-Wen Europe Ltd. | Professional & scientific | 1999 |
| Jeld-Wen UK Limited | Manufacturing | 1951 |
| Jellinek Neurosurgery Limited | Health & social care | 2010 |
| Jelly Bead Limited | Arts & recreation | 2025 |
| Jellybean Photobooth Limited | Administrative & support | 2022 |
| JEM Interiors Ltd | Construction | 2021 |
| JEM Laboratories UK Limited | Financial services | 2021 |
| Jema Healthcare Solutions Limited | Health & social care | 2015 |
| Jemm Lets Ltd | Real estate | 2021 |
| JEN Ltd | Construction | 2025 |
| Jenant Limited | Agriculture & fishing | 2024 |
| Jenhance Limited | Other services | 2025 |
| Jeni Ferguson Pilates Limited | Education | 2012 |
| Jenkies Limited | Hospitality | 2026 |
| Jenkinson Construction Group Limited | Construction | 1999 |
| Jennie Gill Limited | Manufacturing | 2003 |
| Jennie Walshaw Limited | Households | 2013 |
| Jennix Hair & Lifestyle Ltd | Wholesale & retail | 2026 |
| Jenoura Ltd | Manufacturing | 2025 |
| Jenrem Properties Limited | Real estate | 2019 |
| Jensen Communications Limited | Financial services | 2001 |
| Jensen Telecom Ltd | Administrative & support | 2015 |
| Jensen Ventures Limited | Hospitality | 2013 |
| Jenstorm Limited | Arts & recreation | 2012 |
| Jepson Holdings Limited | Manufacturing | 1988 |
| Jera Films Limited | Information & communication | 2022 |
| Jera Property Limited | Real estate | 2018 |
| Jerrot Investments Limited | Financial services | 2018 |
| Jerry Hobby Trade Limited | Wholesale & retail | 2025 |
| Jerrycan Code Ltd | Information & communication | 2017 |
| Jersey Bakers Limited | Manufacturing | 2018 |
| Jersey Properties Ltd | Real estate | 2021 |
| Jerusalem Coffee Shop Ltd | Hospitality | 2016 |
| Jescha Care Services Limited | Administrative & support | 2022 |
| Jescha Healthcare UK Ltd | Wholesale & retail | 2022 |
| Jeslord Professional Services Limited | Professional & scientific | 2025 |
| Jesmack Investiment Limited | Health & social care | 2013 |
| Jess Nails Limited | Wholesale & retail | 2014 |
| Jessica Ennis Limited | Arts & recreation | 2006 |
| Jessica Flinn Ltd | Wholesale & retail | 2010 |
| Jessica Nails&Beauty Limited | Other services | 2021 |
| Jessica Sharpe Weddings Ltd. | Professional & scientific | 2018 |
| Jessica's Little Learners Ltd | Education | 2025 |
| Jesslindov Ltd | Wholesale & retail | 2025 |
| Jessop Financial Planning Limited | Financial services | 2010 |
| Jessop Properties Limited | Real estate | 2024 |
| Jessops Consultancy Services Limited | Real estate | 2007 |
| Jessops F.D. Limited | Professional & scientific | 2014 |
| JET Paint Limited | Construction | 2026 |
| JET7 Logistics Ltd | Transport & logistics | 2023 |
| Jeta Property Holdings Limited | Real estate | 2017 |
| Jetem Solutions Ltd | Health & social care | 2010 |
| Jethire Limited | Wholesale & retail | 1986 |
| Jethro Robinson Limited | Real estate | 2017 |
| Jetm Support Ltd | Wholesale & retail | 2025 |
| Jetskape Gaming Limited | Information & communication | 2022 |
| Jettodan Services Ltd | Administrative & support | 2025 |
| Jeuje Fashion Ltd | Wholesale & retail | 2025 |
| Jewel Blade Limited | Manufacturing | 2003 |
| Jewel Construction Limited | Construction | 1998 |
| Jewellery Store Limited | Wholesale & retail | 2024 |
| Jewelsound Limited | Real estate | 1991 |
| JEX Business Services Ltd | Administrative & support | 2020 |
| JEY Plumbing & Heating Ltd | Construction | 2024 |
| Jeyjoo Ltd | Professional & scientific | 2016 |
| JF Electrical Engineering Limited | Manufacturing | 2024 |
| JF Golf Coaching Ltd | Arts & recreation | 2024 |
| JF Knight Funeral Directors Ltd | Other services | 2021 |
| Jfenn Ltd | Health & social care | 2026 |
| JFH Limited | Households | 2021 |
| JFK Vision Ltd | Information & communication | 2017 |
| JFL Engineering Limited | Construction | 2008 |
| JFS Property Assets Limited | Real estate | 2007 |
| JFS Sales Management Ltd | Wholesale & retail | 2026 |
| JG Cars Limited | Wholesale & retail | 2025 |
| JG Patrick Limited | Professional & scientific | 2018 |
| JG Pears Grid Connection Limited | Energy | 2016 |
| JGA Investments Ltd | Extraterritorial | 2016 |
| JGC Property Developments Ltd | Real estate | 2022 |
| JGH Logistics Limited | Transport & logistics | 2021 |
| Jgmc Property Ltd | Real estate | 2024 |
| JGR Services Ltd | Transport & logistics | 2022 |
| JH Ventilation Ltd | Manufacturing | 2021 |
| JH7 Ltd | Professional & scientific | 2023 |
| JHA Property Services Ltd | Real estate | 2021 |
| JHB Engineering Services Ltd | Professional & scientific | 2019 |
| JHE Consultancy Ltd | Professional & scientific | 2024 |
| Jhinchcliffecoaching Ltd | Extraterritorial | 2025 |
| JHJ Family Properties Limited | Real estate | 2016 |
| JHL Financial Solutions Limited | Professional & scientific | 2010 |
| JHM Estates & Property Management Ltd | Real estate | 2018 |
| JHM Hair Ltd | Other services | 2025 |
| Jhome.Life Ltd | Real estate | 2020 |
| Jhoran.Com Limited | Professional & scientific | 2004 |
| JHP Birmingham Ltd | Hospitality | 2025 |
| JHP F&B Ltd | Hospitality | 2024 |
| JHP London Ltd | Hospitality | 2025 |
| JHR Electrical Ltd | Construction | 2023 |