| JD Marketing & CRM Solutions Limited | Professional & scientific | 2022 |
| Jdig Consulting Limited | Administrative & support | 2023 |
| JDK Management Limited | Real estate | 2021 |
| Jdmc TCG Ltd | Wholesale & retail | 2026 |
| Jdmh Real Estate Limited | Real estate | 2022 |
| JDP Flooring Limited | Construction | 2015 |
| JDR Netherlands Ltd | Professional & scientific | 2012 |
| Jdsa Property Ltd | Real estate | 2017 |
| JE LEE Marketing Limited | Professional & scientific | 2017 |
| JE Smart Ltd | Information & communication | 2024 |
| JEA Discovery Consulting Limited | Professional & scientific | 2024 |
| Jefferies Claims Limited | Administrative & support | 2022 |
| Jefferies Injury Lawyers Limited | Extraterritorial | 2022 |
| Jefferies Law Limited | Extraterritorial | 2022 |
| Jefferies Lawyers Limited | Extraterritorial | 2022 |
| Jefferies Legal Limited | Extraterritorial | 2022 |
| Jefferies LLP | | 2004 |
| Jefford Consulting Services Limited | Professional & scientific | 2017 |
| Jeffrey Bell Architects Limited | Professional & scientific | 2011 |
| Jefo Consult Design Invest (C.D.I) Ltd | Professional & scientific | 2018 |
| JEL Homes Ltd. | Real estate | 2021 |
| Jellylegs Productions Limited | Information & communication | 2007 |
| Jelmac (Primary Care) Properties Limited | Real estate | 2008 |
| JEM Property & Housing Limited | Households | 2025 |
| Jemily Properties Limited | Real estate | 2016 |
| Jena Consultants Limited | Professional & scientific | 2023 |
| Jencon Limited | Professional & scientific | 2024 |
| Jenna Patties Co Ltd | Hospitality | 2023 |
| Jennifer Claire Porter Designs Ltd | Professional & scientific | 2022 |
| Jenny Powell Limited | Information & communication | 1998 |
| Jeremy Howard Ltd | Health & social care | 2010 |
| Jeremy LEE Legal Services Limited | Professional & scientific | 2020 |
| Jesscape Limited | Professional & scientific | 2006 |
| Jessica Stone Salons Limited | Other services | 2024 |
| Jesu Limited | Information & communication | 2021 |
| JET Associates Ltd | Financial services | 2026 |
| JET Sense Ltd | Transport & logistics | 2023 |
| Jet&Co Management Limited | Hospitality | 2024 |
| Jetrac Limited | Extraterritorial | 2014 |
| Jexo Tech Ltd | Information & communication | 2018 |
| JF Financial Solutions Limited | Financial services | 2014 |
| JF SFI Services Ltd | Transport & logistics | 2018 |
| JFC Property Limited | Real estate | 2017 |
| Jfda Limited | Professional & scientific | 2024 |
| Jfls Dent Limited | Health & social care | 2022 |
| JG Legal Limited | Professional & scientific | 2019 |
| JG Sourcing Ltd | Real estate | 2026 |
| JG Stays Ltd | Real estate | 2025 |
| JGB Law Limited | Professional & scientific | 2019 |
| JGD Medical Limited | Health & social care | 2023 |
| JGR Management UK Limited | Professional & scientific | 2020 |
| JHF IT Training Limited | Professional & scientific | 2019 |
| Jhjc Limited | Wholesale & retail | 2014 |
| Jhsf UK Limited | Financial services | 2022 |
| JI Smiles 2 Ltd | Health & social care | 2015 |
| Jihsar Properties Limited | Real estate | 2026 |
| Jini Living Ltd | Real estate | 2023 |
| Jini Medics Ltd | Health & social care | 2017 |
| Jinlong Culture & Performing Arts Ltd | Arts & recreation | 2016 |
| JJ Laurence Business Services Ltd | Professional & scientific | 2024 |
| JJ Power System HV Services Limited | Professional & scientific | 2025 |
| JJA Property Holdings Ltd | Real estate | 2022 |
| JJB Painters Limited | Construction | 2025 |
| JJF Resourcing Solutions Limited | Administrative & support | 2011 |
| JJW Finance Ltd | Financial services | 2025 |
| JKI Electrical Limited | Construction | 2013 |
| Jkia Limited | Real estate | 2017 |
| JKL Transport Ltd | | 2009 |
| JKM Healthcare Ltd | Health & social care | 2026 |
| JKP Advisory Limited | Professional & scientific | 2020 |
| JL Executive Recruitment Ltd | Administrative & support | 2018 |
| JLB Trading Ltd | Construction | 2021 |
| Jldc Consultancy Limited | Administrative & support | 2014 |
| JLI Dens Ltd | Health & social care | 2025 |
| JLM Security Services Ltd | Professional & scientific | 2005 |
| JLR Construction Services Limited | Administrative & support | 2009 |
| JLR Consulting Limited | Professional & scientific | 2025 |
| JLX Logistics Ltd | Transport & logistics | 2025 |
| JM Capital Advisors Ltd | Professional & scientific | 2024 |
| JM Commercial Managment Services Ltd | Professional & scientific | 2024 |
| JM Contractors Roofing Limited | Construction | 2025 |
| JM7 Services Ltd | Health & social care | 2021 |
| JMA & Partners - Consulting, Project & Development LLP | | 2020 |
| Jmac Compliance Limited | Professional & scientific | 2022 |
| JMC Legal Limited | Administrative & support | 2015 |
| Jmcb Care Ltd | Health & social care | 2022 |
| Jmcb Construction Consultancy Ltd | Professional & scientific | 2021 |
| JMK Lettings Ltd | Real estate | 2023 |
| JMK Properties (UK) Ltd | Real estate | 2014 |
| Jmkdigital Limited | Professional & scientific | 2023 |
| Jmkh Studios Ltd | Arts & recreation | 2024 |
| JMS Industrial Relations MGT Ltd | Professional & scientific | 2016 |
| JN Financial Solutions Ltd | Financial services | 2023 |
| Jnair Limited | Health & social care | 2016 |
| JO Doran Limited | Professional & scientific | 2016 |
| JO Folland Landscape Planning Ltd | Professional & scientific | 2022 |
| Jobtrain Limited | Information & communication | 2004 |
| Joby U.K. Limited | Transport & logistics | 2022 |
| Joco Kuma Consulting Limited | Professional & scientific | 2018 |
| JOE Chapman Lighting Limited | Information & communication | 2010 |