| Jack & Paige Transport Ltd | Transport & logistics | 2021 |
| Jack Allison Limited | Health & social care | 2022 |
| Jack Beast Ltd | Transport & logistics | 2018 |
| Jack L Davis Wealth Management Ltd | Financial services | 2018 |
| Jack of ALL Shades Leeds Ltd | Other services | 2017 |
| Jack Slinn Holdings Limited | Financial services | 2021 |
| Jackie Daily Finds Ltd | Wholesale & retail | 2026 |
| Jackie TAN Ltd | Hospitality | 2020 |
| Jackieb Ltd | Health & social care | 2018 |
| Jackjack Ltd | Information & communication | 2013 |
| Jackm Limited | Information & communication | 2024 |
| Jackmus Limited | Extraterritorial | 2018 |
| Jackrabbits Pottery Limited | Manufacturing | 2013 |
| Jacks Consultancy Limited | Information & communication | 2015 |
| Jacks Lane Energy Limited | Energy | 2013 |
| Jackson Anaesthetic Services Ltd | Health & social care | 2022 |
| Jackson Bear Ltd | Professional & scientific | 2023 |
| Jackson Building Contractors Limited | Construction | 2005 |
| Jackson Jackpot Limited | Wholesale & retail | 2023 |
| Jackson Packaging Consultancy Limited | Professional & scientific | 2019 |
| Jackson Parker Consulting Ltd | Information & communication | 2023 |
| Jackson Trophies Limited | Wholesale & retail | 2007 |
| Jackson's (Basingstoke) Limited | Transport & logistics | 1946 |
| Jackson's Transport (Ossett) Limited | Transport & logistics | 1961 |
| Jacksons Fabrication Limited | Manufacturing | 2018 |
| Jacksons Leeds Ltd | Transport & logistics | 2025 |
| Jacksons Motors Vehicle Repairs Ltd | Wholesale & retail | 2022 |
| Jacksons Removals UK Ltd | Transport & logistics | 2025 |
| Jacksons Superbikes Limited | Wholesale & retail | 2012 |
| Jacksonville Holdings Ltd | Real estate | 2026 |
| Jacky Chan Kitchen Ltd | Hospitality | 2019 |
| Jaclin Express Ltd | Transport & logistics | 2025 |
| Jacmay&Co Limited | Professional & scientific | 2014 |
| Jacob Andrew Cosmetics Ltd | Wholesale & retail | 2019 |
| Jacobean Limited | Financial services | 2020 |
| Jacobs & Co Property (UK) Ltd | Real estate | 2025 |
| Jacobs Mobile Mechanics Ltd | Wholesale & retail | 2025 |
| Jacobus Consulting Ltd | Information & communication | 2010 |
| Jacose Investments Limited | Real estate | 2020 |
| Jacose Limited | Information & communication | 2008 |
| Jacques O'Neill Limited | Arts & recreation | 2022 |
| Jacquie Silk (Harome) Limited | Hospitality | 2009 |
| Jacuzzi Spa and Bath Limited | Wholesale & retail | 2012 |
| Jacy Properties Limited | Households | 2024 |
| JAD Data Consultancy Services Ltd | Information & communication | 2022 |
| JAD Property Solutions Limited | Real estate | 2024 |
| JAD Solutions Ltd | Administrative & support | 2022 |
| Jade Kelsall Ltd | Education | 2015 |
| Jade LOU Ltd | Information & communication | 2026 |
| Jade Palace Leeds Ltd | Hospitality | 2021 |
| Jadeliu Limited | Information & communication | 2019 |
| Jadenrange Limited | Manufacturing | 1984 |
| Jadi Property Maintenance Limited | Construction | 2025 |
| Jadid Ventures Ltd | Real estate | 2024 |
| Jadim Freehold Company Limited | Households | 1986 |
| Jadin Limited | Administrative & support | 2016 |
| Jadin Newco Limited | Administrative & support | 2021 |
| Jados Properties Ltd | Real estate | 2024 |
| Jadr Ltd | Transport & logistics | 2015 |
| Jadu 47 Ltd | Real estate | 2019 |
| Jadwell Properties Ltd | Real estate | 2025 |
| JAF Supermarkets Ltd | Wholesale & retail | 2025 |
| Jafar Motor Bike Repair Ltd | Wholesale & retail | 2020 |
| Jafd Limited | Wholesale & retail | 2023 |
| Jaffary Ltd | Health & social care | 2023 |
| JAG Financial Limited | Financial services | 2014 |
| JAG Foods Limited | Wholesale & retail | 2024 |
| Jagger Bros Consultants Limited | Professional & scientific | 2025 |
| Jagger Property Holdings Ltd | Real estate | 2026 |
| Jaggi & Company Limited | Financial services | 1996 |
| JAH Bree Investments | Financial services | 2022 |
| Jahan’S Fusion Ltd | Hospitality | 2025 |
| Jahmoit Healthcare Limited | Administrative & support | 2022 |
| JAI MA Tara Ltd | Wholesale & retail | 2026 |
| JAI Motors Ltd | Wholesale & retail | 2025 |
| Jailbroken Films Limited | Information & communication | 2023 |
| Jailyd Bar and Diner Limited | Hospitality | 2017 |
| Jaimo Ltd | Information & communication | 2026 |
| Jairna Consultancy UK Limited | Professional & scientific | 2012 |
| Jais Freight Forwarding & Office Removal Limited | Other services | 2017 |
| Jaisawals Properties Limited | Real estate | 2022 |
| Jajah. Co Ltd | Wholesale & retail | 2025 |
| JAK Parker Property Management Limited | Households | 2026 |
| JAK61 Ltd | Construction | 2025 |
| Jake Clayton Consulting Ltd | Professional & scientific | 2025 |
| Jake Harris Tuition Ltd | Education | 2022 |
| Jake Smith Financial Services Ltd | Financial services | 2022 |
| Jake Trevor Ltd | Wholesale & retail | 2025 |
| Jake's Dog Treats Ltd | Wholesale & retail | 2022 |
| Jakelin Limited | Professional & scientific | 2022 |
| Jakemarr Limited | Wholesale & retail | 2025 |
| Jakester Ltd | Wholesale & retail | 2025 |
| Jakim Family Ltd | Wholesale & retail | 2022 |
| Jakk's Mann Ltd | Wholesale & retail | 2010 |
| Jakob Hatteland Computer Limited | Information & communication | 2019 |
| Jakpak Holdings Ltd | Real estate | 2020 |
| Jakpak Wrapping Machinery Ltd | Professional & scientific | 2019 |
| Jakub Adelman Services Ltd | Transport & logistics | 2012 |
| Jakub Wojcik Ltd | Transport & logistics | 2021 |
| Jal&T Consulting Limited | Professional & scientific | 2018 |