| JA Property Move Ltd | Real estate | 2023 |
| Jaav Care Ltd | Health & social care | 2020 |
| JAB Property Holdings Limited | Financial services | 2019 |
| Jabba Properties Ltd | Real estate | 2026 |
| Jack Ross Limited | Professional & scientific | 2006 |
| Jack Ross Trustees Limited | Professional & scientific | 2005 |
| Jacked Calisthenics Limited | Education | 2024 |
| Jackson Joinery (Manufacturing) Limited | Manufacturing | 2004 |
| Jacob's Gold Estates Ltd | Real estate | 2022 |
| Jacobs GEN Ltd | Real estate | 2024 |
| Jacobsaero Limited | Manufacturing | 2019 |
| Jacrox Limited | Extraterritorial | 2014 |
| Jade Perfect Limited | Real estate | 2023 |
| Jade Shopfitters Ltd | Construction | 2007 |
| Jadestyle UK Limited | Real estate | 2015 |
| Jadex Britain Group Ltd | Wholesale & retail | 2022 |
| Jaeger Wrexham Holdings Limited | Other services | 2022 |
| Jaff Car Care Ltd | Wholesale & retail | 2023 |
| Jaff Manchester Ltd | Wholesale & retail | 2024 |
| Jaffeman Limited | Real estate | 2025 |
| Jagavany Limited | Real estate | 2026 |
| JAH78 Limited | Administrative & support | 2012 |
| Jak's World C.I.C. | Health & social care | 2023 |
| JAL Building Contractors Ltd | Construction | 2018 |
| JAL Financial Management Limited | Financial services | 2024 |
| Jalen Limited | Manufacturing | 2001 |
| JAM Property Holdings Limited | Other services | 2021 |
| Jamaica Street Estates Limited | Other services | 2017 |
| James & JAY Ltd | Wholesale & retail | 2025 |
| James Hunter Consultancy Services Ltd | Information & communication | 2023 |
| James Nicholas Homes Construction Limited | Construction | 2022 |
| James Nicholas Homes Limited | Construction | 2022 |
| James Nicholas Homes SPV 1 Limited | Construction | 2022 |
| James Nicholas Homes SPV 2 Limited | Construction | 2022 |
| James Nicholas Homes SPV 3 Limited | Construction | 2022 |
| James Nicholas Homes SPV 4 Limited | Construction | 2023 |
| James Nicholas Homes SPV 5 Limited | Construction | 2023 |
| Jamson Legal Limited | Professional & scientific | 2023 |
| JAN Laminate Ltd | Construction | 2025 |
| Jana Holdings Ltd | Financial services | 2024 |
| Jana Property Investments Ltd | Real estate | 2025 |
| Jane Deane Recruitment Limited | Administrative & support | 2014 |
| Jane Hartley Associates Limited | Professional & scientific | 2015 |
| Jane Montague Consultancy Limited | Professional & scientific | 2018 |
| Janine Alexander Legal Limited | Professional & scientific | 2023 |
| Jankowski Property Ltd | Real estate | 2025 |
| Japan Properties Ltd | Real estate | 2019 |
| Japras Property Ltd | Real estate | 2023 |
| Jaqs Limited | Professional & scientific | 2024 |
| JAS Sykes Ltd | Administrative & support | 2023 |
| Jatos & Partners LLP | | 2019 |
| JAVED111 Ltd | Wholesale & retail | 2025 |
| Jayes Trading Limited | Wholesale & retail | 2023 |
| Jayhernandezcomp Ltd | Professional & scientific | 2022 |
| Jaymar Property Group Ltd | Extraterritorial | 2014 |
| Jaytak Care Limited | Health & social care | 2022 |
| Jazz Didsbury Services Ltd | Other services | 2025 |
| Jazzio Limited | Extraterritorial | 2012 |
| Jbgm Investments Ltd | Real estate | 2021 |
| JBM Freight Services Limited | Transport & logistics | 2019 |
| JBS Housing Ltd | Real estate | 2021 |
| JC Ashlei Limited | Health & social care | 2020 |
| JC Smart Care Ltd | Health & social care | 2026 |
| JCB Logistics Limited | Transport & logistics | 2020 |
| JD Law Limited | Professional & scientific | 2018 |
| JDG Property Holdings Limited | Professional & scientific | 2023 |
| Jdhorton.Co Ltd | Professional & scientific | 2023 |
| JDL Plumbing Heating & Bathrooms Limited | Construction | 2020 |
| JDN Roofing Limited | Construction | 2016 |
| Jdna Holdings Limited | Construction | 2024 |
| JDR Origin Ltd | Wholesale & retail | 2026 |
| Je(Uk) Limited | Hospitality | 2026 |
| Jeelani Brothers Ltd | Hospitality | 2025 |
| Jefe Concepts Ltd | Wholesale & retail | 2024 |
| Jellyfish Consultancy Limited | Professional & scientific | 2021 |
| Jellyfish Payroll Limited | Professional & scientific | 2017 |
| Jemitola Properties Ltd | Construction | 2024 |
| Jenkins Commercial Properties Limited | Construction | 1993 |
| Jenkinsons Transport (International) Limited | | 1974 |
| Jenna Keller Events Ltd | Professional & scientific | 2010 |
| Jennie Doolan Dance CIC | Education | 2019 |
| Jennylock Limited | Households | 1978 |
| Jesem Holdings Limited | Financial services | 2012 |
| Jesem Properties Limited | Real estate | 2017 |
| Jess J - Nails and Beauty Ltd | Other services | 2022 |
| Jessieandrews Hair Studio Ltd | Other services | 2026 |
| Jeswanpark Ltd | Real estate | 2013 |
| Jewelery Shop Ltd | Wholesale & retail | 2018 |
| Jezville Ltd | Extraterritorial | 2008 |
| JF Estates Limited | Real estate | 2016 |
| JF Resourcing Ltd | Administrative & support | 2025 |
| Jfca Healthcare Ltd | Health & social care | 2014 |
| Jffi Network Ltd | Administrative & support | 2024 |
| JFJ Traders Ltd | Wholesale & retail | 2024 |
| JG Building Services (UK) Ltd | Construction | 2011 |
| JG Portfolio Limited | Real estate | 2014 |
| JG Property Limited | Real estate | 2016 |
| JGT Property Services Ltd | Construction | 2022 |
| JH Advisory Ltd | Administrative & support | 2022 |
| JH Burns Consulting Ltd | Professional & scientific | 2009 |