| Hospitality Industry Training Ltd | Professional & scientific | 2006 |
| Hove Events Ltd | Arts & recreation | 2023 |
| Howfar Ltd | Information & communication | 2026 |
| HP Property Ventures Ltd | Real estate | 2024 |
| HPQ Trade Ltd | Construction | 2025 |
| HRM Chiropractic Limited | Health & social care | 2004 |
| Hudson Plastering and Refurbishments Ltd | Construction | 2018 |
| Huemate Ltd | Information & communication | 2025 |
| Hugo Lewis Consulting Ltd | Administrative & support | 2016 |
| Human Leadership Studio Ltd | Education | 2020 |
| Hunter Speech Therapy Ltd | Education | 2019 |
| HXN Group Ltd | Professional & scientific | 2016 |
| Hypnotise Digital Ltd | Professional & scientific | 2021 |
| IAN Sykes and Co Limited | Professional & scientific | 2015 |
| ICM Projects Ltd | Construction | 2023 |
| Ideal Investment Property (Brighton) Ltd | Real estate | 2017 |
| Ideal Property Brighton LLP | | 2012 |
| Ideal Property Ditchling RD Ltd | Real estate | 2023 |
| Ideal Property Newburg Ltd | Real estate | 2025 |
| Ideal Property South East Ltd | Real estate | 2021 |
| Ideal Property Sussex Ltd | Construction | 2016 |
| Ignite Stack Limited | Professional & scientific | 2026 |
| Ikshop Ltd | Wholesale & retail | 2025 |
| Ilonart Ltd | Arts & recreation | 2020 |
| IMI Cloud Management Ltd | Information & communication | 2020 |
| In-House Plumbing and Heating Limited | Construction | 2013 |
| Incom Business Systems Limited | Information & communication | 1989 |
| Incom-Cns Group Limited | Professional & scientific | 2003 |
| Incom-Cns Wales Limited | Information & communication | 2018 |
| Independent Coffee and Croissant Ltd | Hospitality | 2024 |
| Indigo Cultural Consulting Limited | Professional & scientific | 2007 |
| Industrial Crane Services UK Limited | Manufacturing | 2019 |
| Inferno 374 Limited | Hospitality | 2022 |
| Infinite Construction Group Ltd | Construction | 2022 |
| Infinity Construction Group South East Ltd | Construction | 2021 |
| Infomoto Ltd | Financial services | 2003 |
| Infosec Cloud Ltd | Information & communication | 2006 |
| Ingenious Food Solutions Ltd | Manufacturing | 2024 |
| Ingenium Consulting Engineers Ltd | Professional & scientific | 2015 |
| Ingredient Communications Limited | Information & communication | 2017 |
| Inn Property Matters Limited | Construction | 2017 |
| Innovant Limited | Administrative & support | 2006 |
| Innovation Fitness Limited | Manufacturing | 2015 |
| Inopia Limited | Professional & scientific | 2022 |
| Inset Online Ltd | Information & communication | 2007 |
| Inside I.T. Solutions Limited | Information & communication | 2002 |
| Inside JOB Ltd | Professional & scientific | 2019 |
| Inspire YOU Wellbeing Limited | Professional & scientific | 2021 |
| Intangible Ltd | Information & communication | 2025 |
| INTEGER8 Limited | Administrative & support | 2009 |
| Interail (UK) Limited | Other services | 2003 |
| Into the Blue Restaurant Ltd | Hospitality | 2015 |
| Intrinsic Recruitment Limited | Administrative & support | 2011 |
| Inverta Group Limited | Information & communication | 2026 |
| Involve Selection Limited | Administrative & support | 2009 |
| Ipinnacle Ltd | Information & communication | 2008 |
| ISC Style Ltd | Wholesale & retail | 2012 |
| Isyt Accounting Limited | Professional & scientific | 2016 |
| IT Recruitment Solutions Ltd | Administrative & support | 2018 |
| J Donegan Limited | Real estate | 2014 |
| J Lepp Enterprise Limited | Wholesale & retail | 2025 |
| J Williams Heating Ltd | Construction | 2016 |
| J. Parsons & Sons Limited | Construction | 1959 |
| J4A Industries Ltd | Information & communication | 2021 |
| JA Lounge Ltd | Hospitality | 2025 |
| Jackrabbit Ltd | Administrative & support | 2022 |
| Jagua Ltd | Other services | 2010 |
| James Wingate Ltd | Financial services | 2019 |
| Janegi Investments Limited | Real estate | 1991 |
| Jarry FM Ltd | Real estate | 2020 |
| Jarry FM Properties Limited | Real estate | 2022 |
| JB Film & Media Ltd | Information & communication | 2024 |
| JC Financial Services Limited | Financial services | 2016 |
| Jenner Construction Ltd | Construction | 2019 |
| Jenner Hospitality Ltd | Hospitality | 2024 |
| Jennytwellsep Limited | Health & social care | 2025 |
| Jessica Hayler Aesthetics Ltd | Health & social care | 2026 |
| Jessica Hayler Ltd | Other services | 2015 |
| JET Flight & Instructor Training Ltd | Transport & logistics | 2007 |
| JET Flight Training Ltd | Transport & logistics | 2007 |
| Jet’M Ltd | Manufacturing | 2026 |
| Jkcn Group Ltd | Hospitality | 2025 |
| JKR Industries Ltd | Wholesale & retail | 2018 |
| JL Cleaning Services Ltd | Administrative & support | 2020 |
| JMC Events Ltd | Administrative & support | 2025 |
| Jms-Construction Building and Renovation Ltd | Construction | 2025 |
| Jobiqo UK Ltd | Information & communication | 2019 |
| Jocawa Group Ltd | Wholesale & retail | 2018 |
| Jocawa Property Ltd | Real estate | 2020 |
| John Adlam Associates Limited | Professional & scientific | 2013 |
| John Challen Limited | Information & communication | 2008 |
| John F Mcgill Ltd | Professional & scientific | 2005 |
| Joint Solutions Limited | Health & social care | 1999 |
| JON Cooke Ltd | Professional & scientific | 2014 |
| Jones Grab Services Ltd | Water & waste | 2020 |
| Joseph Bader Ltd | Information & communication | 2023 |
| Josh Lane Plumbing Services Ltd | Construction | 2022 |
| Jove Group Ltd | Construction | 2018 |
| Jovo App Ltd | Information & communication | 2024 |
| JP Carpentry and Construction Ltd | Construction | 2024 |