| James & Phillips Limited | Construction | 2003 |
| James JH Trading Limited | Wholesale & retail | 2025 |
| JAS Electrical Ltd | Construction | 2022 |
| Jawjaw Ltd | Information & communication | 2016 |
| Jaytec Glass Limited | Manufacturing | 2004 |
| JC130 Limited | Professional & scientific | 2010 |
| JCA Seminars Limited | Education | 2014 |
| JCR Electrics Limited | Construction | 2014 |
| Jelaco Properties Limited | Real estate | 2016 |
| JEN and Ollie Ltd | Education | 2017 |
| Jenco Properties (Hastings) Limited | Real estate | 2016 |
| Jennings-Bramly Furniture Limited | Manufacturing | 2011 |
| Jenwick Cocopod Ltd | Real estate | 2023 |
| Jeremy Grey Consultancy Ltd | Financial services | 2026 |
| Jeremy Ward Consultancy Ltd | Professional & scientific | 2024 |
| Jericho Road Solutions Ltd | Professional & scientific | 2012 |
| JFN Heritage Limited | Wholesale & retail | 2025 |
| JGL Associates Limited | Professional & scientific | 2021 |
| JH Rail Civils Drainage Ltd | Construction | 2025 |
| JH Sons Ltd | Transport & logistics | 2016 |
| JIN Xuan Ltd | Hospitality | 2022 |
| Jingleworks International Ltd | Agriculture & fishing | 2015 |
| JK KJ Ltd | Administrative & support | 2025 |
| JLC Country Landscapes Limited | Administrative & support | 2014 |
| JMB Projects & Developments Ltd | Construction | 2019 |
| Johnson Bespoke Joinery and Metal Fabrication Ltd | Manufacturing | 2021 |
| Jolly Good Brands Limited | Extraterritorial | 2006 |
| JON RAY Building Limited | Construction | 2002 |
| Jones & Cooper Ltd | Administrative & support | 2025 |
| Jones Labourers Limited | Administrative & support | 2019 |
| Josh Rhodes Limited | Arts & recreation | 2013 |
| Joss Bay Surf School Ltd | Arts & recreation | 2019 |
| JPB Pricing Contracting Ltd | Financial services | 2025 |
| JPM Invest Limited | Financial services | 2023 |
| JQT Developments Limited | Real estate | 2025 |
| JRD Benjamins Limited | Real estate | 2018 |
| JRM Entertainment Ltd | Hospitality | 2026 |
| JSB Theatre LLP | | 2025 |
| JTP Plumbing and Heating Solutions Limited | Construction | 2025 |
| Jubilee+ | Other services | 2013 |
| Jumbo's Caravans Limited | Administrative & support | 2003 |
| Jumping COW Education Ltd | Education | 2020 |
| Justine ANN Ltd | Wholesale & retail | 2025 |
| Justyn Barnes Media Limited | Administrative & support | 2005 |
| JW Electrical Contractors Hastings Ltd | Construction | 2026 |
| Jw-Ph Ltd | Construction | 2024 |
| Jwcroft Ltd | Wholesale & retail | 2020 |
| Jypamas Limited | Manufacturing | 2019 |
| K B a Haulage Limited | Transport & logistics | 2020 |
| K R Windows Limited | Construction | 2011 |
| K V & H J Martin Ltd | Administrative & support | 2019 |
| K.L.E Scaffolding Limited | Construction | 2018 |
| K59 Ltd | Hospitality | 2026 |
| Kaiveganuk Ltd | Hospitality | 2022 |
| Kanaan Management Services Ltd | Wholesale & retail | 2024 |
| Kanryo Projects Ltd | Construction | 2025 |
| Kardas Properties Limited | Real estate | 2020 |
| Kardia Care Ltd | Arts & recreation | 2019 |
| Kashan Shop Ltd | Wholesale & retail | 2025 |
| Kasspeedloan Ltd | Financial services | 2026 |
| Kate Bacon Limited | Professional & scientific | 2006 |
| KBR South East Ltd | Construction | 2023 |
| KCF Investments Limited | Real estate | 2013 |
| KDS Homes Ltd | Administrative & support | 2026 |
| Kdsz Investments UK Ltd | Real estate | 2012 |
| Kebab Mania Ltd | Hospitality | 2025 |
| Keeley Park Holdings Ltd | Financial services | 2026 |
| Kelly Andrews Psychotherapy Ltd | Health & social care | 2023 |
| Kensington Property & Developments Ltd | Real estate | 2023 |
| Kent and Sussex Statics Ltd | Transport & logistics | 2023 |
| Kent and Sussex Tree Services Limited | Agriculture & fishing | 2022 |
| Kent Development & Engineering Limited | Information & communication | 2022 |
| Kent Eagles Speedway Club Ltd | Education | 2026 |
| Kent Statics Limited | Extraterritorial | 2025 |
| Kent Tackle (Hawkhurst) Limited | Wholesale & retail | 2010 |
| Kent Tackle Limited | Extraterritorial | 2010 |
| Kerbsons Ltd | Other services | 2021 |
| Kerla Limited | Administrative & support | 2025 |
| Kevin Peter Ardagh (NP Lewis) Limited | Administrative & support | 2014 |
| Kewhurst House Ltd | Households | 1957 |
| Keygrip Consultancy Ltd | Professional & scientific | 2017 |
| Keyvan Investments Ltd | Real estate | 2021 |
| Kibella Property Management Ltd | Construction | 2025 |
| Kibur Holdings Limited | Financial services | 2026 |
| Kidsdoart Ltd | Extraterritorial | 2013 |
| Kileys Contract Flooring Ltd | Wholesale & retail | 2005 |
| Kilncroft Lodge RTM Company Limited | Households | 2024 |
| KIM Star Nails Ltd | Other services | 2024 |
| Kingcraft Technologies Ltd | Information & communication | 2026 |
| Kingsley Properties Limited | Real estate | 1995 |
| Kingsman Ground Care Limited | Agriculture & fishing | 2025 |
| Kingswood Court Limited | Households | 1957 |
| Kins MED Ltd | Manufacturing | 2020 |
| Kismet Digital Consulting Ltd | Information & communication | 2018 |
| Kit-Co Drywall Limited | Administrative & support | 2017 |
| Kites Nest (Hastings) Limited | Households | 2014 |
| KL Project Services Ltd | Professional & scientific | 2024 |
| Klotts Construction Limited | Construction | 2025 |
| Knowles & Co South East Ltd | Transport & logistics | 2018 |
| Koffee Matters Ltd | Manufacturing | 2026 |