| Hmsp International (UK) Limited | Construction | 2020 |
| Hogarth Management Limited | Professional & scientific | 1996 |
| Holbrook Digital Consultancy Ltd. | Information & communication | 2016 |
| Holbus Project Management Limited | Information & communication | 2021 |
| Holmsteed Farm Limited | Wholesale & retail | 2003 |
| Holt's Irrigation Ltd | Manufacturing | 2024 |
| Homegarth (Freehold) Limited | Real estate | 2025 |
| Honeybee Films Limited | Information & communication | 2013 |
| Hong XI Ltd | Hospitality | 2024 |
| Horam Chapel | Other services | 2012 |
| Horam Historic Storage Ltd | Transport & logistics | 2022 |
| Horam Nails Limited | Other services | 2024 |
| Horizon Instruments Limited | Manufacturing | 1984 |
| HP Sauce Ltd | Professional & scientific | 2024 |
| Huffey Construction Ltd | Construction | 2024 |
| Hullwell Limited | Households | 1980 |
| Humorous Hops Limited | Administrative & support | 2021 |
| Huntons Limited | Financial services | 2024 |
| Hurst Shaw Gardens Residents Association Limited | Households | 1967 |
| Hurstwood Feeds Limited | Wholesale & retail | 2003 |
| Hwrfc Trading Limited | Hospitality | 2025 |
| Hybank Ltd | Real estate | 2020 |
| Ibis Investments Limited | Professional & scientific | 1998 |
| Icoserv 2015 Limited | Wholesale & retail | 2001 |
| Icoserv Security Limited | Administrative & support | 2018 |
| Image Matters Signage Ltd | Manufacturing | 2016 |
| Imago DEI CIC | Wholesale & retail | 2022 |
| Impending Geese Limited | Arts & recreation | 2023 |
| Imperial Motor Company Limited | Wholesale & retail | 2002 |
| Index Health Ltd | Health & social care | 2024 |
| Indialantic Property Limited | Professional & scientific | 2016 |
| Innovated 1 Ltd | Professional & scientific | 2025 |
| Insightia Holdings Ltd | Financial services | 2020 |
| International Arts Partnership | Education | 2016 |
| International Arts Studio | Arts & recreation | 1982 |
| Invatek Computer Services Limited | Information & communication | 1994 |
| Iron Tridents Limited | Other services | 2025 |
| Irrigatingly Simple Ltd | Wholesale & retail | 2020 |
| Isenhurst Limited | Hospitality | 2008 |
| Isenhurst Management Company Limited | Households | 1999 |
| ISO Doctor Ltd | Professional & scientific | 2016 |
| Iumentis Consultancy Ltd | Manufacturing | 2019 |
| Ivano Limited | Real estate | 1999 |
| Izzard Holdings Ltd | Financial services | 2025 |
| J Dyer Carpentry Ltd | Construction | 2019 |
| J Gorwyn Limited | Agriculture & fishing | 2011 |
| J H Pitts & Sons Ltd | Agriculture & fishing | 2011 |
| J Jarvis Electrical Ltd | Construction | 2022 |
| J Jarvis Property Ltd | Real estate | 2024 |
| J L P Groundwork Limited | Construction | 2017 |
| J. Roberts Electrical Limited | Construction | 2008 |
| J.C.Jenkins(Butchers)Limited | Real estate | 1955 |
| J.Hassall Property Ltd | Real estate | 2024 |
| Jack Driscoll Limited | Information & communication | 2014 |
| James & Wyatt Consulting Ltd | Professional & scientific | 2023 |
| James Collins Guitars Limited | Manufacturing | 2014 |
| James Hayter Farriers Limited | Other services | 2007 |
| James Henry Holdings Ltd | Financial services | 2023 |
| James Henry Homes Ltd | Construction | 2025 |
| James Podiatry Ltd | Health & social care | 2014 |
| James Pollard Limited | Professional & scientific | 1991 |
| JAN & Julia Limited | Manufacturing | 2021 |
| Jarvis Tech Holdings Limited | Financial services | 2020 |
| Jarvis Tech Limited | Wholesale & retail | 2001 |
| Java INS Brokers Ltd | Financial services | 2025 |
| JCC Ferguson LLP | | 2008 |
| JCG Enterprises Limited | Wholesale & retail | 2024 |
| JDW Electrical Sussex Ltd | Construction | 2024 |
| Jellyfish Junction Ltd | Professional & scientific | 2025 |
| Jencos Systems Limited | Information & communication | 2001 |
| JGM Technology Limited | Information & communication | 2024 |
| JHD Agri Ltd | Agriculture & fishing | 2017 |
| JKC Plumbing & Heating Limited | Construction | 2012 |
| JMP Flight Training Ltd | Education | 2014 |
| JMW Digital Health Ltd | Information & communication | 2024 |
| John Davis Real Estate and Consulting Ltd | Real estate | 2018 |
| Jones Britain Limited | Wholesale & retail | 2009 |
| JRP Direct Limited | Transport & logistics | 2002 |
| JT Holdings Limited | Real estate | 2001 |
| Juice Electrical Services Limited | Extraterritorial | 2015 |
| Just Flow Ltd | Other services | 2026 |
| Just Historic Cars Limited | Wholesale & retail | 2016 |
| K & M Equipment Ltd | Manufacturing | 2006 |
| K&M Cars Limited | Wholesale & retail | 2019 |
| Kane Building Contractors Limited | Construction | 2013 |
| Kasa Moris Limited | Hospitality | 2022 |
| KAY & Pascoe LLP | | 2011 |
| Kazatan Games Ltd | Manufacturing | 2020 |
| KBC Legal Consulting Ltd | Professional & scientific | 2024 |
| KDL Law Limited | Professional & scientific | 2020 |
| Keith Hunt Management Ltd | Administrative & support | 2010 |
| Kendale Catering Ltd | Hospitality | 2006 |
| Kent of Sussex Catering Ltd | Hospitality | 2018 |
| Kestrel Homecare Limited | Health & social care | 2010 |
| Kevin Wells Welding & Fabrication Limited | Construction | 2010 |
| KG Developers Limited | Real estate | 2021 |
| Kids ABC Limited | Wholesale & retail | 2018 |
| Kilmaine Road NO 34 Limited | Households | 2008 |
| Kingsline Solutions Limited | Information & communication | 2009 |
| Kingston Hill Limited | Professional & scientific | 1999 |