| Jidesco Limited | Health & social care | 2014 |
| Jins & Janice Ltd | Real estate | 2026 |
| JJ Brand Consultancy Limited | Professional & scientific | 2021 |
| JJ Clarke Property (UK) Ltd | Hospitality | 2022 |
| JJ Commercials Fleet Assist Limited | Professional & scientific | 2023 |
| JJ Greenway Limited | Financial services | 2015 |
| JJ Media Limited | Information & communication | 2020 |
| JJ Prints Limited | Manufacturing | 2022 |
| JJ Webb Retail Ltd | Wholesale & retail | 2015 |
| Jj&Chics Ltd | Real estate | 2024 |
| Jj's Sound & Music Limited | Manufacturing | 2013 |
| JJD Property Services Ltd | Real estate | 2025 |
| JJL Consulting Solutions Limited | Administrative & support | 2024 |
| Jjlp Management Ltd | Hospitality | 2020 |
| JJS Construction & Development Ltd | Construction | 2015 |
| JJS Contracting Ltd | Construction | 2024 |
| JJS Services Essex Limited | Hospitality | 2024 |
| JJS Tuition Basildon Limited | Education | 2017 |
| JK Construction & Design Limited | Construction | 2025 |
| JK Contracts Ltd | Construction | 2022 |
| JK Group Management Ltd | Real estate | 2020 |
| JK Heating & Plumbing Limited | Construction | 2015 |
| JK Real Estate Limited | Real estate | 2007 |
| JKD Landscaping and Fencing Limited | Construction | 2018 |
| JLB Consultancy Ltd | Administrative & support | 2023 |
| JLC Scaffolding Services Limited | Construction | 2025 |
| JLD Plumbing Solutions Ltd | Construction | 2026 |
| JLP Keys Ltd | Real estate | 2024 |
| JLW Enterprises Ltd | Other services | 2024 |
| JLX Properties Limited | Households | 2025 |
| JM Care Franchising Ltd | Health & social care | 2020 |
| JM Fire Protection Services Ltd | Construction | 2022 |
| JM Properties Essex Ltd | Real estate | 2025 |
| JM SET Ltd | Manufacturing | 2023 |
| JM Specialist Contracts Limited | Construction | 2022 |
| JMB Residentials Ltd | Real estate | 2025 |
| JMC Earthworks Ltd | Administrative & support | 2023 |
| Jmes Services Ltd | Construction | 2022 |
| JMF Projects Ltd | Construction | 2026 |
| Jmfafara Limited | Real estate | 2026 |
| JMG Access Solutions Ltd | Construction | 2021 |
| JMH Property Group Limited | Real estate | 2025 |
| JMJ Invest Ltd | Real estate | 2025 |
| JMK Scaffolding Services Limited | Construction | 2016 |
| Jmon Global Ltd | Health & social care | 2022 |
| JMS Electrical (Services) Limited | Construction | 2008 |
| JNG Construction & Engineering Limited | Transport & logistics | 1998 |
| JNH Management Consulting Limited | Households | 2025 |
| JNJ Support Services Ltd | Health & social care | 2017 |
| JNR Resource Ltd | Administrative & support | 2007 |
| JO Coletta Skin Ltd | Other services | 2023 |
| JO Coletta Skincare Ltd | Wholesale & retail | 2023 |
| Jo&Az Ltd | Construction | 2026 |
| Jo-Bi Martial Arts Limited | Arts & recreation | 2007 |
| Joamo Limited | Other services | 2023 |
| Jocharl Services Limited | Professional & scientific | 2016 |
| JOE Property Ltd | Households | 2023 |
| John Atwell Transport Limited | Transport & logistics | 2006 |
| John General Construction Ltd | Construction | 2016 |
| John Gracious Health Limited | Health & social care | 2011 |
| John Hunter Heating Limited | Construction | 2023 |
| John James Luxury Travel Ltd | Administrative & support | 2006 |
| John LEE D.O.P. Limited | Information & communication | 2017 |
| John Newman Transport Limited | Other services | 2018 |
| John Rodwell Limited | Extraterritorial | 1982 |
| John Root Consultancy Limited | Professional & scientific | 2005 |
| John Townshend Limited | Construction | 2025 |
| John Walsh Pipefitting & Welding Limited | Construction | 2017 |
| John Waters Limited | Other services | 2023 |
| Johnnidriving Limited | Transport & logistics | 2018 |
| Johnson Inspection Services & Consultancy Ltd | Construction | 2025 |
| Johnson’S Heating Ltd | Construction | 2023 |
| Johnston Baxter Limited | Construction | 2022 |
| Johnston-Hartin Ltd | Health & social care | 2025 |
| Joinery Solutions Limited | Construction | 2001 |
| Joint.Gl Ltd | Construction | 2015 |
| Jojo London Ltd | Professional & scientific | 2025 |
| Jokesonfun Limited | Health & social care | 2020 |
| Jolie MOI Concessions Limited | Wholesale & retail | 2013 |
| Jolie MOI Holdings Ltd | Financial services | 2023 |
| Jolie MOI Properties Ltd | Real estate | 2023 |
| Jollof Rice Depot Food Ltd | Hospitality | 2025 |
| Jollof Rice Depot Ltd | Hospitality | 2024 |
| JON Lloyd Homes Ltd | Real estate | 2021 |
| JON Robert OPS Limited | Wholesale & retail | 2025 |
| JON ST Pierre Ltd | Hospitality | 2020 |
| Jonalls Limited | Construction | 2021 |
| Jonathan Butcher Developments Ltd | Construction | 2021 |
| Jonic Contracts Ltd | Construction | 2025 |
| Jonmaesa Limited | Real estate | 2018 |
| Jordanzunigaphotography Ltd | Professional & scientific | 2024 |
| Jorose Soft Solutions Limited | Information & communication | 2015 |
| Joseph and Sons Ltd | Hospitality | 2026 |
| Joseph Business Solutions Ltd | Professional & scientific | 2021 |
| Jotonia Consulting Limited | Wholesale & retail | 2015 |
| Jotson Ltd | Real estate | 2020 |
| Joy's Hair Beauty, Make-Up and Gele Ltd | Other services | 2022 |
| Joyce Media Hire Limited | Administrative & support | 2025 |
| Joyfuljoy Ltd | Other services | 2024 |
| Joysinceforever Ltd | Information & communication | 2019 |