| J.E.B Vehicle Hire Ltd | Administrative & support | 2024 |
| J.E.F Contractors Ltd | Construction | 2022 |
| J.H. (Lifting Gear Hire) Limited | Professional & scientific | 1972 |
| J.S. Brickwork Solutions Ltd | Construction | 2025 |
| J.W. Challis & Co. Limited | Manufacturing | 1977 |
| Jaathav Ltd | Wholesale & retail | 2022 |
| JAB (Kent) Ltd | Health & social care | 2018 |
| Jack Christian Properties Ltd | Real estate | 2022 |
| Jackiejoe Resources Ltd | Health & social care | 2023 |
| Jackwood Travel Ltd | Administrative & support | 2020 |
| Jacobian Ltd. | Wholesale & retail | 2017 |
| Jacqui Sansom Ltd | Other services | 2011 |
| Jagged Social Ltd | Education | 2024 |
| JAH Know Ltd | Hospitality | 2025 |
| Jahbean Limited | Information & communication | 2019 |
| Jailler-Law Sports Limited | Wholesale & retail | 2019 |
| Jake Eastwood Drylining Limited | Construction | 2026 |
| Jake Pitcher QS Ltd | Professional & scientific | 2025 |
| Jakob Alexander Mortgages Ltd | Financial services | 2026 |
| Jambila Music Limited | Manufacturing | 2005 |
| Jambo Africa Community Limited | Arts & recreation | 2025 |
| James Brown AV Ltd | Administrative & support | 2018 |
| James Miles Fishing Ltd | Agriculture & fishing | 2025 |
| James Thomas Properties Ltd | Real estate | 2024 |
| Jamesco Limited | Public administration | 2001 |
| Jamika Limited | Real estate | 2011 |
| Jasc Property Limited | Real estate | 2014 |
| Jasmine Cleaning (Kent) Ltd | Administrative & support | 2020 |
| JBC (Jones Building & Carpentry) Limited | Construction | 2024 |
| JC Reardon Holdings Limited | Real estate | 2021 |
| Jdecs Limited | Manufacturing | 2009 |
| JDP Roofing Limited | Construction | 2014 |
| Jecs Hair & Beauty Ltd | Other services | 2018 |
| Jecs Offshore Scaffolding Ltd | Manufacturing | 2014 |
| Jentex Energy Management Services Ltd | Wholesale & retail | 2025 |
| Jetlee Washing Services Ltd | Administrative & support | 2025 |
| Jf&C Investments Ltd | Financial services | 2022 |
| Jf&C Properties Ltd | Real estate | 2022 |
| JHA Investments Kent Ltd | Real estate | 2024 |
| Jiffy Media Limited | Professional & scientific | 2016 |
| JIM Pratt Ltd | Information & communication | 2011 |
| Jireh Consultancy Limited | Information & communication | 2024 |
| JJ Communications Ltd | Information & communication | 2017 |
| JJ UK Group Ltd | Other services | 2016 |
| JJ UK Limited | Construction | 2005 |
| Jjscc Ltd | Real estate | 2023 |
| Jjuk Protective Coatings Ltd | Construction | 2025 |
| JJW Solutions Ltd | Construction | 2020 |
| JKS Education Limited | Education | 2023 |
| JKW Multi Services Ltd | Water & waste | 2026 |
| JLC Installations Ltd. | Construction | 2024 |
| JM Investment Fund Limited | Wholesale & retail | 2009 |
| JM Restaurant Concepts Ltd | Hospitality | 2017 |
| JMH Salons Limited | Other services | 2024 |
| JOE Joiner Studios Limited | Administrative & support | 2022 |
| John Davis Taylor Wholesale Ltd | Wholesale & retail | 2024 |
| John Foreman & Partners Limited | Professional & scientific | 2014 |
| John Hatswell Limited | Other services | 1969 |
| Johnsons Wine Imports Ltd | Wholesale & retail | 2016 |
| Jolm Properties Ltd | Real estate | 2024 |
| JON Nickoll Music Limited | Information & communication | 2005 |
| JON P Holdings Limited | Financial services | 2022 |
| JON P Ventures Limited | Real estate | 2022 |
| JON Penberthy Marketing Ltd | Information & communication | 2014 |
| Jonathan C Winternheimer Psychotherapy Limited | Health & social care | 2015 |
| Joosup Ltd | Information & communication | 2022 |
| Joseph Court (Broadstairs) Management Company Limited | Households | 2006 |
| Joygym Limited | Arts & recreation | 2026 |
| JP Paintworx Ltd | Wholesale & retail | 2019 |
| JRC Construction Ltd | Construction | 2019 |
| Jrhd Services Ltd | Manufacturing | 2024 |
| JS Analysis & Reporting Limited | Information & communication | 2011 |
| JS Bridges Ltd | Hospitality | 2025 |
| JS Real Estate Partners Ltd | Extraterritorial | 2017 |
| JSR Drywall Ltd | Construction | 2010 |
| Jsre Investment Limited | Extraterritorial | 2017 |
| Jsre Land Limited | Extraterritorial | 2017 |
| Jsre Limited | Extraterritorial | 2017 |
| Jsre Property Limited | Extraterritorial | 2017 |
| Jsre Surveyors Limited | Extraterritorial | 2017 |
| Jtecommerce Ltd | Wholesale & retail | 2025 |
| JTM Consulting Ltd | Professional & scientific | 2024 |
| Jude Greenaway Ltd | Information & communication | 2023 |
| Judeylight Limited | Administrative & support | 2022 |
| Judges Consultancy Limited | Professional & scientific | 2014 |
| Junior Science Community Interest Company | Education | 2025 |
| Just Discos Ltd | Other services | 2010 |
| Just Graze Ltd | Hospitality | 2023 |
| Just Kids Parties Ltd | Arts & recreation | 2010 |
| Just the JOB Grounds Gardens and Estates Ltd | Administrative & support | 2026 |
| Justfood Limited | Hospitality | 2023 |
| Justj Ltd | Wholesale & retail | 2022 |
| Justmarketinguk Ltd | Professional & scientific | 2025 |
| JW Fire Protection Limited | Public administration | 2013 |
| K R S Interiors Limited | Construction | 2008 |
| K. Wilson Developments Ltd | Construction | 2011 |
| K1W1 Engineering Ltd | Wholesale & retail | 2019 |
| K9 Kindergarten Enterprises Limited | Extraterritorial | 2014 |
| K9 Kindergarten Limited | Other services | 2013 |
| K9-UK Equipment Supplies Ltd | Manufacturing | 2025 |