| Jarovittrade Ltd | Wholesale & retail | 2021 |
| Jascare Ltd | Health & social care | 2016 |
| Jasmin Powell Limited | Wholesale & retail | 2023 |
| Jaso Holdings Ltd | Financial services | 2020 |
| Jason Keffert Photography Limited | Professional & scientific | 2009 |
| Jason Woodhams Cashflow-Properties Ltd | Construction | 2020 |
| Jason Woodhams Ltd | Real estate | 2009 |
| Jasper Education and Support Services Limited | Health & social care | 2018 |
| Java Green Ltd | Construction | 2019 |
| Java Group Ltd | Hospitality | 2019 |
| Javor Limited | Wholesale & retail | 2023 |
| JAY and Co Foods Ltd | Wholesale & retail | 2026 |
| Jayceeyg Media Limited | Professional & scientific | 2022 |
| JB Brighton Ltd | Professional & scientific | 2013 |
| Jbarchitect Limited | Professional & scientific | 2012 |
| Jbennett Limited | Professional & scientific | 2012 |
| JBI Design & Engineering Ltd | Professional & scientific | 2020 |
| JBT Events Co. Limited | Hospitality | 2026 |
| JC Edwards Ltd | Information & communication | 2025 |
| JC Global Consulting Ltd | Professional & scientific | 2025 |
| JC Pet Services Limited | Other services | 2026 |
| Jc&H Limited | Financial services | 2022 |
| Jcmot Ltd | Health & social care | 2016 |
| Jcorbs Limited | Information & communication | 2020 |
| JCR Enterprises Ltd | Professional & scientific | 2022 |
| JCS Building Services Ltd | Construction | 2023 |
| JDB Legal and Tax Training Limited | Professional & scientific | 2013 |
| JDF (UK) Limited | Financial services | 2011 |
| JDG Solutions Limited | Information & communication | 2025 |
| JDH Telecoms Services Ltd | Administrative & support | 2017 |
| Jedi Enterprises Limited | Real estate | 2000 |
| Jefferies Farm Car Sales Limited | Extraterritorial | 2020 |
| Jellyfish Accounting Ltd | Professional & scientific | 2018 |
| JEM Agency Ltd | Professional & scientific | 2022 |
| JEM Project Services Limited | Professional & scientific | 2009 |
| Jemmabell Limited | Information & communication | 2023 |
| Jemuco Limited | Real estate | 2022 |
| Jenid Ltd | Professional & scientific | 2011 |
| Jennifer & Lawrence Investment Holdings Ltd | Other services | 2019 |
| Jennings Residential Ltd | Real estate | 2023 |
| Jenny Beavan Designs Limited | Arts & recreation | 2004 |
| JEP Lettings Ltd | Administrative & support | 2016 |
| Jeremia Enterprises Limited | Hospitality | 2026 |
| Jeremy Lynch Limited | Arts & recreation | 2010 |
| Jeremy Lynch Properties Limited | Real estate | 2016 |
| Jeremy Sherman Ltd | Arts & recreation | 2013 |
| Jeremy Silverthorne Fine Jewellery Ltd | Wholesale & retail | 2007 |
| Jerry & N Private Limited | Wholesale & retail | 2022 |
| Jessica & Co Decorating Ltd | Construction | 2026 |
| Jessica OUT of the Closet Ltd | Information & communication | 2016 |
| Jets Partnership Limited | Real estate | 2025 |
| Jewish Womens AID Limited | Other services | 1995 |
| JFC Consultancy Services Limited | Information & communication | 2023 |
| Jfdek Limited | Professional & scientific | 2008 |
| JFP Build & Construction Ltd | Construction | 2025 |
| JGW Construction Ltd | Construction | 2025 |
| JHB Law Ltd | Professional & scientific | 2017 |
| JHD Property Investments Ltd | Real estate | 2025 |
| JIM Jam's @ Worthing Football Club Ltd | Hospitality | 2026 |
| JIM Jam's Bakes & Barista Ltd | Hospitality | 2021 |
| JIM Jam's Catering Ltd | Hospitality | 2023 |
| JIM Jams of Tarring Ltd | Hospitality | 2024 |
| Jimblesjimjams Ltd | Extraterritorial | 2016 |
| Jimmar International Holding Limited | Financial services | 2020 |
| Jinde Limited | Health & social care | 2005 |
| JIW Property Group Limited | Real estate | 2025 |
| JJ Treding Limited | Wholesale & retail | 2026 |
| Jj&H Accounting Services Limited | Professional & scientific | 2023 |
| JJC Joinery and Construction Limited | Manufacturing | 2025 |
| Jjdg Management Limited | Households | 2015 |
| JJH Pension Strategies Limited | Other services | 2018 |
| JJL Tech Limited | Information & communication | 2016 |
| Jjlm Consulting Ltd | Information & communication | 2025 |
| JJM Catering Services Ltd | Hospitality | 2019 |
| JJR Property Investments Limited | Real estate | 2020 |
| JJW Investments Ltd | Real estate | 2024 |
| JK Editing Limited | Information & communication | 2010 |
| JK Prospects Ltd | Real estate | 2022 |
| Jkarol Limited | Information & communication | 2009 |
| Jklewis Investments Limited | Financial services | 2022 |
| Jksbioscience Limited | Professional & scientific | 2016 |
| JL Electrical Group Ltd | Construction | 2023 |
| JL Hair & Wellness Limited | Other services | 2024 |
| JL Projects (Sussex) Ltd | Construction | 2026 |
| JL Property Hive Ltd | Real estate | 2025 |
| Jlaj Commercial Ltd | Real estate | 2025 |
| Jlaj Investments SPV Ltd | Real estate | 2025 |
| JLB Accountancy Services Limited | Professional & scientific | 2014 |
| JLH Carpentry Ltd | Construction | 2019 |
| Jlmv Property Holding Limited | Real estate | 2024 |
| JLP Surgical Ltd | Health & social care | 2026 |
| JLW Strategy Limited | Professional & scientific | 2022 |
| Jlww Academy Ltd | Arts & recreation | 2018 |
| Jlww Holdings Limited | Financial services | 2019 |
| Jlww Talent Limited | Arts & recreation | 2018 |
| JM Electrical (Sussex) Ltd | Construction | 2017 |
| Jmac Developments (Southern) Limited | Construction | 2008 |
| JMB Additions LLP | | 2007 |
| JMD Network Solutions Ltd | Information & communication | 2023 |
| Jmmcarbon Ltd | Manufacturing | 2025 |