| Infinicare Limited | Health & social care | 2020 |
| Infinistar Limited | Professional & scientific | 2018 |
| Infinity London PVT Ltd | Wholesale & retail | 2023 |
| Infinityx Digital Ltd | Information & communication | 2026 |
| Infinnerty GAS Ltd | Construction | 2021 |
| Infonet Consultancy Limited | Other services | 2013 |
| Informed HCP Ltd | Information & communication | 2026 |
| Inintech Ltd. | Information & communication | 2023 |
| Inish Haulage Ltd | Water & waste | 2022 |
| Inishowen Homes Ltd | Real estate | 2024 |
| Inko Contractors Ltd | Construction | 2023 |
| Innovience Ltd | Construction | 2022 |
| Innovision Components Limited | Other services | 2025 |
| Innovision Group Limited | Administrative & support | 2005 |
| Inovext Ltd | Information & communication | 2025 |
| Insito Finance Ltd | Professional & scientific | 2016 |
| Inspire ICT Ltd | Information & communication | 2010 |
| Insure Security Services Ltd | Administrative & support | 2024 |
| Integra Property Solutions Limited | Construction | 2021 |
| Integrated Core Solutions Limited | Information & communication | 2022 |
| Intellectus Consulting Limited | Professional & scientific | 2023 |
| Intellicode Solutions Ltd | Wholesale & retail | 2025 |
| Intelligent Workspaces Group Ltd | Information & communication | 2020 |
| Intelligent Workspaces Management Ltd | Professional & scientific | 2023 |
| Intelligent Workspaces Property Ltd | Other services | 2010 |
| Intelligent Workspaces Services Ltd | Administrative & support | 2024 |
| Intelliprop Limited | Real estate | 2009 |
| Intercept Pest Solutions Ltd | Administrative & support | 2026 |
| International Contruction Ltd | Other services | 2020 |
| International Organization of Creativity for Peace | Education | 2016 |
| Inti Removal Limited | Transport & logistics | 2020 |
| Into Health Limited | Administrative & support | 2020 |
| Inventico Ltd | Wholesale & retail | 2025 |
| Invest Create Ltd | Construction | 2021 |
| Investbury Ltd | Construction | 2017 |
| Investmentco Ltd | Wholesale & retail | 2023 |
| Investments 360 Limited | Real estate | 2003 |
| IO Microservices Ltd | Information & communication | 2022 |
| Iofml UK Ltd | Wholesale & retail | 2026 |
| IP Health Ltd | Health & social care | 2025 |
| IPD Revolution UK Ltd | Construction | 2022 |
| IQ MOT and Auto Services Ltd | Wholesale & retail | 2023 |
| Iraq Football POD Ltd | Professional & scientific | 2026 |
| IRS and Sons Ltd | Real estate | 2019 |
| Isaacol Ltd | Real estate | 2024 |
| Ishaaron Limited | Education | 2025 |
| Ishan Electrical Service Limited | Construction | 2021 |
| Isher Carpenters Limited | Manufacturing | 2018 |
| ISI Construction Limited | Construction | 2017 |
| ISK Developments Limited | Real estate | 2025 |
| Islamia Limited | Extraterritorial | 2018 |
| Isolarity Ltd | Professional & scientific | 2011 |
| Istorage Limited | Wholesale & retail | 2009 |
| IT Network Consulting Ltd | Information & communication | 2015 |
| ITA Interpreting, Translation & Advice Co Ltd Limited | Professional & scientific | 2015 |
| Itbotnet Ltd | Information & communication | 2023 |
| Itec Security Limited | Administrative & support | 2014 |
| Itms London Limited | Information & communication | 2010 |
| Itnext Limited | Information & communication | 2025 |
| ITS Bargain Ltd | Wholesale & retail | 2015 |
| ITS Computers Limited | Wholesale & retail | 1995 |
| ITS Laboratories Ltd | Information & communication | 2013 |
| Iuvenis Aesthetics Limited | Wholesale & retail | 2016 |
| Ivaleo Limited | Information & communication | 2013 |
| Ivan & Stela Engneering Ltd. | Transport & logistics | 2019 |
| Iwaaz Ltd | Real estate | 2020 |
| Iyana Cosmetics Ltd | Wholesale & retail | 2020 |
| J & a Builders London Ltd | Construction | 2014 |
| J & B Bakery Ltd | Wholesale & retail | 2026 |
| J & B Property Ltd | Real estate | 2016 |
| J & D Properties (London) Limited | Real estate | 2006 |
| J & J Properties London Limited | Real estate | 2014 |
| J & J Transport Limited | Construction | 1993 |
| J & S K Ltd | Wholesale & retail | 2010 |
| J & S Removal Services Ltd | Transport & logistics | 2017 |
| J a Neill Property Limited | Real estate | 2025 |
| J J Coughlan (Holdings) Limited | Construction | 2014 |
| J Liss Ltd | Other services | 2024 |
| J P at the Swan Limited | Hospitality | 2019 |
| J R Automative Ltd | Wholesale & retail | 2024 |
| J V Partnership Ltd | Administrative & support | 2013 |
| J&A Homes Ltd | Real estate | 2026 |
| J&N Commercial Cleaning Ltd | Administrative & support | 2025 |
| J&R Investment Holdings Ltd | Real estate | 2020 |
| J&T Halai Limited | Real estate | 2024 |
| J. Conde Consulting Limited | Administrative & support | 2017 |
| J.H.Construction Limited | Construction | 2016 |
| J.J.Coughlan Limited | Construction | 1970 |
| J3SR LLP | | 2006 |
| JA Global Holdings Ltd | Financial services | 2024 |
| JAD Enterprises Ltd | Real estate | 2015 |
| Jaden Properties Ltd | Households | 2024 |
| Jaff Barber Shop Limited | Other services | 2023 |
| Jaffna Airways Limited | Administrative & support | 2025 |
| JAG and Land Properties Limited | Real estate | 2018 |
| JAG and Land UK Parts Ltd | Wholesale & retail | 2016 |
| Jagatt (Holdings) Limited | Other services | 2014 |
| Jagazi Limited | Wholesale & retail | 2014 |
| Jahans Trading UK Ltd | Wholesale & retail | 2023 |
| Jahnavi Limited | Professional & scientific | 2025 |