| JON Richard Enterprises Ltd | Construction | 2017 |
| JON Skelton Sports Psychology Limited | Extraterritorial | 2025 |
| Jonas and Jonas Consulting Ltd | Professional & scientific | 2023 |
| Jonathan Beacher Limited | Information & communication | 2022 |
| Jones Design and Engineering Services Ltd | Financial services | 2025 |
| Jono's Coffee Limited | Manufacturing | 2020 |
| Jonvic Traders Limited | Manufacturing | 2016 |
| Joon Productions Ltd | Information & communication | 2012 |
| Jordan & Whyte Engineering Ltd | Construction | 2023 |
| Jordan Cars Holdings Limited | Financial services | 2019 |
| Jordan Inc Limited | Real estate | 2004 |
| Jordan Properties Limited | Real estate | 1989 |
| Jordan’S Barber & Beauty Ltd | Other services | 2026 |
| Joscelyne Chase Commercial Limited | Real estate | 2004 |
| Joscelyne Chase Limited | Real estate | 2003 |
| Josh G Barber Ltd | Other services | 2021 |
| Josh Ryan Limited | Professional & scientific | 2021 |
| Joshil Learning Ltd | Education | 2023 |
| Joshua Ayettey Design Consultancy Ltd | Professional & scientific | 2023 |
| Joshua Charles Limited | Construction | 2016 |
| Joshua Finch Limited | Real estate | 2024 |
| Joshua King Electrical Services Limited | Construction | 2020 |
| Joslin IT Services Ltd | Information & communication | 2016 |
| Journey of Rebecoming Ltd | Health & social care | 2025 |
| Joyce Solutions Company Limited | Information & communication | 2007 |
| Joyces Farm Trading Ltd | Wholesale & retail | 2019 |
| Joyful Care for YOU Ltd | Health & social care | 2023 |
| JP Family Estates Ltd | Real estate | 2026 |
| JPB Tech Consultancy Limited | Professional & scientific | 2018 |
| JPC Construction Limited | Construction | 2007 |
| JPC Developers Ltd | Construction | 2018 |
| JPC Properties (Essex) Ltd | Real estate | 2018 |
| Jpilates Limited | Education | 2012 |
| JPK Property Solutions Ltd | Administrative & support | 2018 |
| JPL Brickwork & Building Limited | Construction | 2014 |
| JPS Farms Limited | Agriculture & fishing | 2018 |
| JR Signature Homes Ltd | Real estate | 2025 |
| JRH Automotive Limited | Administrative & support | 2024 |
| JRL Decorating Ltd | Construction | 2023 |
| JRL International Limited | Administrative & support | 2025 |
| JRL Watson Accountants Limited | Professional & scientific | 2014 |
| JRM Plumbing & Heating Ltd | Construction | 2024 |
| Jrpn Properties Limited | Real estate | 2015 |
| JRPROPERTIES134 Limited | Real estate | 2021 |
| JRR Inspection Services Limited | Manufacturing | 2012 |
| JRS Cromwell Consulting Limited | Professional & scientific | 2024 |
| JRS Holding Group Ltd | Wholesale & retail | 2026 |
| JRT Consultancy Limited | Administrative & support | 2016 |
| JS Event Caterers Ltd | Wholesale & retail | 2019 |
| JS Notary Ltd | Professional & scientific | 2026 |
| JS Vintiner Venture Limited | Real estate | 2024 |
| JS3 Consultancy Ltd | Information & communication | 2024 |
| JSB 0407 Ltd | Health & social care | 2020 |
| JSK Accountancy Limited | Professional & scientific | 2016 |
| JSM Specialist Services Limited | Construction | 2009 |
| JSW Holdings Limited | Professional & scientific | 1982 |
| JT Buey Ltd | Wholesale & retail | 2020 |
| JT Event Services Ltd | Hospitality | 2023 |
| JT Rail Limited | Construction | 2017 |
| JTD Arts Ltd | Arts & recreation | 2017 |
| JTJ Property Limited | Real estate | 2020 |
| JTK Services Limited | Health & social care | 2015 |
| JTM8 Limited | Real estate | 2021 |
| JTM9 Limited | Real estate | 2025 |
| JTP Mortgage Services Ltd | Financial services | 2022 |
| JU Dachi Martial Arts Ltd | Education | 2018 |
| Jubilee Investments Limited | Real estate | 2006 |
| Judah Grace Limited | Health & social care | 2014 |
| Judo UK Ltd | Wholesale & retail | 2008 |
| Judo Water Treatment Ltd | Wholesale & retail | 2008 |
| Judy Properties Limited | Construction | 1958 |
| Juice Philosophy Limited | Manufacturing | 2014 |
| Juicing With Luke Limited | Manufacturing | 2021 |
| Julant Holdings Limited | Financial services | 2016 |
| Julant Limited | Real estate | 2004 |
| Jules Breach Ltd | Information & communication | 2016 |
| Julia George Associates Limited | Administrative & support | 2000 |
| Jumkan Services Ltd | Information & communication | 2011 |
| Jump Resourcing Limited | Administrative & support | 2007 |
| Juniper Education Group Limited | Financial services | 2019 |
| Juniper Education Holdco Limited | Financial services | 2019 |
| Juniper Education Holdings Limited | Financial services | 2019 |
| Juniper Education Limited | Information & communication | 2019 |
| Juniper Education Midco Limited | Financial services | 2019 |
| Juniper Education Newco Limited | Financial services | 2020 |
| Juniper Education Services Limited | Information & communication | 2019 |
| Junk Space Ltd | Water & waste | 2019 |
| Jupiter Engineering Essex Limited | Construction | 2005 |
| Just Because Flowers Limited | Wholesale & retail | 2018 |
| Just BEE Creative Limited | Administrative & support | 2022 |
| Just Boilers Ltd | Construction | 2021 |
| Just Children Ltd | Health & social care | 2012 |
| Just Families Ltd | Health & social care | 2012 |
| Just Hire Global Ltd | Information & communication | 2020 |
| Just Imagine Story Centre Limited | Wholesale & retail | 2010 |
| Just Pampered Limited | Other services | 2010 |
| Just the Gym Ltd | Arts & recreation | 2024 |
| Just Wing IT Ltd | Hospitality | 2019 |
| Justin Kelly Limited | Construction | 2019 |
| Justminutes Ltd | Transport & logistics | 2019 |