| JESSX2 Limited | Real estate | 2022 |
| Jessy Potts Limited | Professional & scientific | 2025 |
| Jessybestcleaning Ltd | Administrative & support | 2020 |
| JESUS4EVER Limited | Health & social care | 2023 |
| Jesz Limited | Health & social care | 2025 |
| JET Alliance Services Ltd | Real estate | 2018 |
| JET Journals Limited | Wholesale & retail | 2024 |
| Jetcpuk Ltd | Information & communication | 2024 |
| Jetex S.A. | | 1989 |
| Jethaco Limited | Professional & scientific | 2002 |
| Jethwa Properties Limited | Real estate | 2016 |
| Jethwas Clothing Ltd | Wholesale & retail | 2016 |
| Jethwas Properties Ltd | Real estate | 2017 |
| Jetpack Marketing Limited | Professional & scientific | 2019 |
| Jetred Ltd | Professional & scientific | 2016 |
| Jett Exterior Cleaning Limited | Administrative & support | 2024 |
| Jett Window Cleaning Limited | Administrative & support | 2024 |
| Jewel (UK) Ltd | Manufacturing | 2012 |
| Jewel Home Care Ltd | Health & social care | 2018 |
| Jewel UK Bidco Limited | Wholesale & retail | 2012 |
| Jewel UK Midco Limited | Wholesale & retail | 2012 |
| Jewellery Outlet Limited | Manufacturing | 2025 |
| Jeya Retail Ltd | Wholesale & retail | 2022 |
| Jeysal.Km Limited | Professional & scientific | 2019 |
| JEZ Pike Carpentry & Building Services Limited | Manufacturing | 2016 |
| JF Civil/Structural & Temporary Works Consultants Ltd | Construction | 2020 |
| JF Designs Ltd | Professional & scientific | 2024 |
| JF Electrical/Mechanical Limited | Energy | 2010 |
| Jfirst Ltd | Wholesale & retail | 2018 |
| JFR Flat Roofing Ltd | Construction | 2023 |
| Jftc Limited | Administrative & support | 2020 |
| JG Commercial Installations Limited | Construction | 2012 |
| JG Conveyancing Ltd | Professional & scientific | 2026 |
| JG Couriers Ltd | Transport & logistics | 2024 |
| JG Fencing Ltd | Construction | 2022 |
| JG Independent Ltd | Transport & logistics | 2020 |
| JG Insulation Ltd | Construction | 2025 |
| JG Rewind Services Ltd | Manufacturing | 2024 |
| JG85 Ltd | Administrative & support | 2016 |
| JGA Haulage Limited | Transport & logistics | 2018 |
| JGB Business Services Ltd | Construction | 2021 |
| JGJ Ltd | Construction | 2025 |
| JGT Group Limited | Financial services | 2026 |
| JH Bodyworks Limited | Wholesale & retail | 2015 |
| JH Commercial Investments Ltd | Real estate | 2023 |
| JH Imports Ltd | Wholesale & retail | 2025 |
| JH2 Group Ltd | Construction | 2024 |
| JHA Commercial Ltd | Real estate | 2021 |
| JHA Enterprises Limited | Wholesale & retail | 2015 |
| Jhan's UK Ltd | Other services | 2018 |
| Jhander Haulage Ltd | Transport & logistics | 2025 |
| Jhap Healthcare Ltd | Wholesale & retail | 2023 |
| JHF Flooring Solutions Ltd | Construction | 2024 |
| JHH Sales & Marketing Limited | Wholesale & retail | 2014 |
| JHJ Waste Management Limited | Extraterritorial | 2004 |
| Jhsa Ltd | Real estate | 2023 |
| Jhsmartphone Ltd | Wholesale & retail | 2018 |
| Jhutty Food Services Ltd | Hospitality | 2025 |
| JHW Properties Limited | Real estate | 2022 |
| Jiangnan Spring Limited | Hospitality | 2023 |
| Jibby Ltd | Manufacturing | 2014 |
| Jidee Limited | Information & communication | 2012 |
| Jieo Limited | Real estate | 2025 |
| Jifffi Foods Ltd | Wholesale & retail | 2024 |
| Jigsaw Counselling Ltd | Health & social care | 2014 |
| Jigsaw Holistic Planning Ltd | Administrative & support | 2009 |
| JIL Technologies Limited | Information & communication | 2014 |
| Jillian Blair and Company UK Ltd | Other services | 2025 |
| Jillian Holdings Ltd | Real estate | 2022 |
| Jilo Limited | Transport & logistics | 2017 |
| JIM Taylor Engineering Ltd | Information & communication | 2017 |
| Jimmy Jason Global Ltd | Health & social care | 2012 |
| Jimphras Ltd | Wholesale & retail | 2019 |
| Jimsh Trading Ltd | Hospitality | 2021 |
| Jimsuns Limited | Wholesale & retail | 2025 |
| Jim’S Healthcare Ltd | Health & social care | 2022 |
| Jinabi Ltd | Information & communication | 2023 |
| Jingtong UK Ltd | Real estate | 2025 |
| Jinli Barwell Limited | Hospitality | 2024 |
| Jiocart Ltd | Other services | 2021 |
| Jireh Habitation UK Ltd | Real estate | 2025 |
| Jireh Healthcare Services Ltd | Health & social care | 2022 |
| JIT Midland Limited | Professional & scientific | 2026 |
| JIT Singh Consulting Limited | Professional & scientific | 2022 |
| Jites Motor Sales Ltd | Wholesale & retail | 2023 |
| Jitfit- Just in Time Fitness Limited | Arts & recreation | 2014 |
| Jitmost Limited | Administrative & support | 2025 |
| Jitu Ltd | Wholesale & retail | 2026 |
| Jituvalji Ltd | Wholesale & retail | 2023 |
| Jivan Mani Group Ltd | Extraterritorial | 2017 |
| Jivan Mani Investments Ltd | Real estate | 2016 |
| Jiwa Investments Limited | Real estate | 2017 |
| Jiwan Associates Limited | Real estate | 2025 |
| Jiya Health Care Limited | Health & social care | 2023 |
| Jiya Ratia Limited | Real estate | 2021 |
| Jiya Retail Ltd | Wholesale & retail | 2026 |
| Jiya Sales UK Limited | Wholesale & retail | 2026 |
| JJ & KE Properties Ltd | Extraterritorial | 2022 |
| JJ Cobb Limited | Real estate | 2021 |
| JJ DA Lion Ltd | Arts & recreation | 2026 |