| Jjkdh Ltd | Information & communication | 2024 |
| JJR Ecommerce Ltd | Administrative & support | 2026 |
| JJS Aviation Limited | Professional & scientific | 2015 |
| Jkmc Associates Limited | Other services | 2025 |
| JLD Secretarial Services Ltd | Administrative & support | 2012 |
| JLH Interiors Limited | Construction | 2015 |
| JLH Kitchens (Sussex) Limited | Wholesale & retail | 2024 |
| Jlid Property Limited | Real estate | 2019 |
| JLP Nominees Limited | Professional & scientific | 2001 |
| JM Bathrooms Ltd | Construction | 2024 |
| JM Portfolio Ltd | Administrative & support | 2024 |
| JMH (UK1) Limited | Manufacturing | 1959 |
| JMM Properties Limited | Real estate | 2014 |
| JMS Vehicle Conversions Ltd | Wholesale & retail | 2018 |
| JMS Vehicle Storage Ltd | Transport & logistics | 2021 |
| Jnfs Properties Ltd | Real estate | 2021 |
| JO Grimwood Enterprises Limited | Administrative & support | 2015 |
| JO Hyder Limited | Administrative & support | 2016 |
| Johbar Consulting Limited | Information & communication | 2007 |
| John Broomfield Removals Ltd | Transport & logistics | 2013 |
| John Cowan Archive Ltd | Administrative & support | 2019 |
| John Green Consultancy Limited | Information & communication | 2007 |
| John Salako Enterprises Limited | Professional & scientific | 2003 |
| Johnson's Gardens Ltd | Construction | 2019 |
| Johnston & Partners Limited | Wholesale & retail | 2016 |
| Johnstone Grounds & Gardens Limited | Administrative & support | 2012 |
| Jonathan LEA Limited | Professional & scientific | 2011 |
| Jonathan Talley Architects Limited | Professional & scientific | 2021 |
| Jones Consultancy Services (Sussex) Ltd | Professional & scientific | 2012 |
| JOS & Co Homes Ltd | Real estate | 2023 |
| Josco Homes Ltd | Real estate | 2024 |
| Josef Limited | Professional & scientific | 2005 |
| Joshua Hayday Helping Hand Trust | Health & social care | 2009 |
| JP Electrical Svcs. Sussex Ltd | Construction | 2010 |
| JPM Executive Consulting Ltd | Professional & scientific | 2024 |
| JR Commerce Ltd | Wholesale & retail | 2025 |
| JR Mentoring Ltd | Professional & scientific | 2026 |
| JRF Developments Sussex Limited | Construction | 2014 |
| JRK Productions Ltd | Information & communication | 2023 |
| JSG Scaffolding Ltd | Construction | 2024 |
| JSM2013 Limited | Arts & recreation | 2013 |
| JT Timmington Ltd | Construction | 2021 |
| Juanita Pablo Company Limited | Health & social care | 2012 |
| Judd Wood LLP | | 2011 |
| Judges Choice Petfood Limited | Manufacturing | 2000 |
| Juice UP Limited | Manufacturing | 2021 |
| Juicy Lemons Ltd | Arts & recreation | 2023 |
| Juniper Workshop Limited | Construction | 2026 |
| Just Call James Limited | Construction | 2012 |
| Just One Small Step Limited | Health & social care | 2010 |
| JUST4U Property Limited | Real estate | 2018 |
| JW Consultancy Solutions Limited | Professional & scientific | 2009 |
| JYI Limited | Professional & scientific | 2026 |
| K & a AKS Ltd | Wholesale & retail | 2017 |
| K F Martin Properties Limited | Real estate | 2021 |
| K R Braine Carpets Limited | Wholesale & retail | 2020 |
| K-Pem Consulting Ltd | Construction | 2021 |
| K30 Glass Limited | Construction | 2018 |
| Kadali Limited | Transport & logistics | 2014 |
| Kadiyski Limited | Wholesale & retail | 2025 |
| Kairos Consulting and Coaching Ltd | Professional & scientific | 2026 |
| Kaizen Sussex Ltd | Professional & scientific | 2023 |
| Kalinabeautytg Limited | Other services | 2023 |
| Kalon Education Ltd | Professional & scientific | 2022 |
| Kangaroos MID Sussex | Health & social care | 2012 |
| Karoo Morning Ltd | Professional & scientific | 2023 |
| Karvor Consulting Limited | Professional & scientific | 2013 |
| Kashdan Group Ltd | Professional & scientific | 2025 |
| KAT Perry Production Ltd | Professional & scientific | 2022 |
| Kathra Consulting Ltd | Professional & scientific | 2019 |
| Katie Elizabeth Design Limited | Professional & scientific | 2025 |
| Katz Auto Services Limited | Wholesale & retail | 2009 |
| KAY Coaching and Consulting Ltd | Professional & scientific | 2020 |
| Kaycee Veterinary Products Limited | Manufacturing | 1976 |
| Kaykozel Music Services Ltd | Education | 2023 |
| KB Consulting & Review Limited | Professional & scientific | 2018 |
| KB Facility Services Ltd | Construction | 2025 |
| KBC Public Relations & Marketing Ltd. | Professional & scientific | 2000 |
| KBL Building and Landscaping Limited | Construction | 2018 |
| Kcpt Ltd | Professional & scientific | 2011 |
| KCW Management Ltd | Administrative & support | 2018 |
| KDM Property Investments Ltd | Real estate | 2020 |
| Keeble Road Works Limited | Construction | 2025 |
| Keenday Ltd | Professional & scientific | 2025 |
| Keep Cool Limited | Energy | 2022 |
| Keith Lewry Installations Ltd | Construction | 2016 |
| Kelly Engineering Solutions Ltd | Professional & scientific | 2014 |
| Kelmsley Food Limited | Hospitality | 2015 |
| Kelshd Limited | Hospitality | 2025 |
| Kelverion Automation Limited | Information & communication | 2010 |
| Kelverion UK Limited | Information & communication | 2010 |
| Kemptown Construction South Limited | Construction | 2016 |
| Kendel Fairley Consulting Limited | Professional & scientific | 2003 |
| Kennedy E-Commerce Ltd | Wholesale & retail | 2021 |
| Kennedy Garden Retreats Ltd | Construction | 2019 |
| Kennedy Landscapes & Gardens Ltd | Administrative & support | 2015 |
| Kensington Refrigeration Limited | Manufacturing | 2004 |
| Kent Building and Construction Ltd | Construction | 2021 |
| Kent Farm Ltd | Real estate | 2022 |
| Kering International Limited | Administrative & support | 2012 |