| Infinite Intermediate Care Limited | Health & social care | 2016 |
| Infinitehorizongroup Ltd | Wholesale & retail | 2026 |
| Infinity Cabs Transport Services Ltd | Transport & logistics | 2023 |
| Infinity Cooling Ltd | Manufacturing | 2022 |
| Infinity Renewables Group Ltd. | Construction | 2018 |
| Infinity Solutions Ltd | Information & communication | 2022 |
| Infinitya Services Ltd | Transport & logistics | 2024 |
| Infrastructure Project Services Ltd | Construction | 2018 |
| Infusion Booth Ltd | Other services | 2026 |
| Ingenious Services Ltd | Construction | 2015 |
| Initial Limited | Administrative & support | 1893 |
| Initial Medical Services Limited | Administrative & support | 1996 |
| Inkling Ltd | Manufacturing | 2017 |
| Inner Sculpting Ltd | Wholesale & retail | 2017 |
| Innivatech Ltd | Wholesale & retail | 2025 |
| Innorec Ltd | Administrative & support | 2023 |
| Innovate Group Limited | Financial services | 2025 |
| Innovate Recruitment Limited | Professional & scientific | 2005 |
| Innovation Electrical (Services) Limited | Construction | 2013 |
| Innovational Healthcare Ltd | Extraterritorial | 2020 |
| Innovative Property Investments Limited | Real estate | 2013 |
| Innovie Ltd | Professional & scientific | 2011 |
| Inscor Healthcare Ltd | Health & social care | 2017 |
| Inside RH Ltd | Professional & scientific | 2012 |
| Insight Information Services Limited | Information & communication | 1997 |
| Insight Lettings Ltd | Real estate | 2010 |
| Inspired Education Group Ltd. | Education | 2023 |
| Inspired Minds Limited | Information & communication | 2000 |
| Inspory Limited | Information & communication | 2023 |
| Insta Computers Ltd | Other services | 2023 |
| Install on Glass Ltd | Construction | 2024 |
| Instalrite Design Ltd | Construction | 2007 |
| Instalrite Properties Ltd | Real estate | 2014 |
| Instant Courier Services Ltd | Transport & logistics | 2025 |
| Instant Designing Ltd | Wholesale & retail | 2025 |
| Instant Glass & Glazing Limited | Construction | 2017 |
| Instant Windows & Doors Limited | Construction | 2023 |
| Institute of Munition Clearance Engineers | Other services | 1998 |
| Instrumentation Products & Services Ltd | Wholesale & retail | 2019 |
| Int'L GRC Advisory Ltd | Administrative & support | 2017 |
| Intchim Limited | Construction | 1975 |
| Integrate Investments Limited | Financial services | 2026 |
| Integrated Computer Enterprises Limited | Information & communication | 2008 |
| Integrated Healthcare Properties Limited | Professional & scientific | 2017 |
| Integrated Kitchens Limited | Construction | 2003 |
| Integrated Security Manufacturing Holdings Limited | Manufacturing | 2003 |
| Integrated Security Manufacturing Limited | Manufacturing | 1988 |
| Integritas Ventures Limited | Professional & scientific | 2018 |
| Intellitrack Ltd | Information & communication | 2021 |
| Intellprint Ltd | Wholesale & retail | 2018 |
| Intercleanse Limited | Administrative & support | 2001 |
| Intergalactic Interactive Ltd | Information & communication | 2023 |
| Interim Management International Limited | Professional & scientific | 2000 |
| Interior Contracts (UK) Limited | Administrative & support | 1999 |
| International Centre for Responsible Tourism Global CIC | Education | 2024 |
| International Diplomatic Supplies Limited | Wholesale & retail | 2005 |
| International Surrey Football Ltd | Arts & recreation | 2019 |
| Interparcel Limited | Transport & logistics | 2004 |
| Intersciencefire Ltd | Professional & scientific | 2025 |
| Intim V Ltd | Wholesale & retail | 2019 |
| Intimeparcel Ltd | Transport & logistics | 2023 |
| Intinas Ltd | Wholesale & retail | 2024 |
| Intraomni Ltd | Other services | 2021 |
| Intrinsia Ltd | Administrative & support | 2018 |
| Intuition Recruitment Ltd | Administrative & support | 2026 |
| Invest Gatwick Diamond GDI | Other services | 2025 |
| Invstr Capital Limited | Professional & scientific | 2011 |
| Ione-Atelier Ltd | Wholesale & retail | 2025 |
| Ions Electrical Limited | Construction | 2022 |
| IOP Sussex Ltd | Professional & scientific | 2013 |
| Iotp Ltd | Hospitality | 2018 |
| IPS Judge Limited | Financial services | 2013 |
| IQ Locking Solutions Limited | Wholesale & retail | 2007 |
| IQ Trading Sussex Ltd | Other services | 2019 |
| Irepair Fones Limited | Manufacturing | 2018 |
| Irma FEL Ltd | Health & social care | 2021 |
| Iron Brothers Limited | Wholesale & retail | 2025 |
| ISG Topservice Ltd | Transport & logistics | 2014 |
| Ishaan Property & Developments Ltd | Real estate | 2022 |
| Isher Milk Limited | Manufacturing | 2026 |
| Islams Brighton Ltd | Hospitality | 2026 |
| Islam’S Crawey 1 Ltd | Hospitality | 2022 |
| Islam’S Crawey Ltd | Hospitality | 2022 |
| Isle Properties Limited | Real estate | 1964 |
| Istanbul Grill Kebab Ltd | Hospitality | 2013 |
| IT First Ltd | Information & communication | 2025 |
| IT Premier Solution Provider Ltd | Information & communication | 2022 |
| IT Solution Kosta Ltd | Transport & logistics | 2018 |
| Italia Solutions UK Ltd | Wholesale & retail | 2020 |
| Italian Pizza Ltd | Hospitality | 2014 |
| Italian Pizzaria Ltd | Hospitality | 2024 |
| Italiatech Ltd | Wholesale & retail | 2023 |
| Itculate Limited | Extraterritorial | 2010 |
| Itek Trading Ltd | Households | 2021 |
| ITJ Removals Ltd | Transport & logistics | 2021 |
| It’S Ted’S Ltd | Wholesale & retail | 2022 |
| Ivana Consultants Ltd | Administrative & support | 2017 |
| Ivara Consulting Ltd | Professional & scientific | 2026 |
| Ivira Ltd | Transport & logistics | 2024 |
| IVM Homes Ltd | Construction | 2026 |