| Iceni Aerospace Solutions Limited | Manufacturing | 2011 |
| Icesys Ltd | Other services | 2013 |
| ICF Team Ltd | Construction | 2017 |
| Icknield Way Limited | Real estate | 2009 |
| Icme Training Ltd | Education | 2025 |
| Icmt Investments Ltd | Real estate | 2022 |
| ICO Trans Limited | Transport & logistics | 2015 |
| Icon Graphics Limited | Manufacturing | 2002 |
| Icon International Ltd | Health & social care | 2024 |
| Icon Medical Limited | Professional & scientific | 2023 |
| Icon Property Investment (Herts) Limited | Hospitality | 1995 |
| Iconic Cuts Hairdressors Ltd | Other services | 2024 |
| Iconic Cuts Kiosk Ltd | Other services | 2021 |
| Iconic Cuts Ltd | Other services | 2020 |
| Iconic Events & Entertainment (UK) Limited | Hospitality | 2024 |
| Iconic Furniture Co., Ltd | Wholesale & retail | 2025 |
| Iconic Games Cache Limited | Manufacturing | 2024 |
| Iconic Media Concepts Limited | Information & communication | 2019 |
| Iconic Wealth International Ltd | Administrative & support | 2021 |
| ICS Solutions Limited | Wholesale & retail | 2024 |
| ICT Transport Limited | Transport & logistics | 2025 |
| ID Medical Group Holdings Limited | Financial services | 2018 |
| ID Medical Group Limited | Administrative & support | 1999 |
| ID Medical Limited | Extraterritorial | 2002 |
| ID Medical US Limited | Extraterritorial | 2006 |
| ID Search & Selection Limited | Extraterritorial | 2002 |
| ID8 Consulting Limited | Information & communication | 2017 |
| Idaza Ltd | Professional & scientific | 2024 |
| Idea Pro AI Ltd | Information & communication | 2022 |
| Ideal Car Service Station Ltd | Wholesale & retail | 2024 |
| Ideal Courier Services Ltd | Transport & logistics | 2026 |
| Ideal Furniture Limited | Manufacturing | 1961 |
| Ideal Group International Limited | Wholesale & retail | 2018 |
| Ideal Incorporation Ltd | Wholesale & retail | 2016 |
| Ideal Properties MK Ltd | Real estate | 2026 |
| Idealcombi UK Limited | Wholesale & retail | 2011 |
| Idealogical Ltd | Professional & scientific | 2025 |
| IDEAS2IT Solutions Limited | Information & communication | 2025 |
| Identifi Global Resources Holdings Limited | Financial services | 2020 |
| Identifi Global Resources Limited | Administrative & support | 2015 |
| Identity Recruitment Limited | Administrative & support | 2022 |
| Idesigner Limited | Professional & scientific | 2024 |
| Idgas Holdings Limited | Administrative & support | 2016 |
| IDJ Photography Ltd | Professional & scientific | 2011 |
| IDK Builder Ltd | Construction | 2025 |
| Idmk Ltd | Other services | 2020 |
| IDP Logistics Ltd | Transport & logistics | 2025 |
| IDS Group III Limited | Financial services | 2021 |
| IE HA Assets Ltd | Real estate | 2025 |
| Ieagle Ltd | Administrative & support | 2019 |
| IEU Associates Limited | Administrative & support | 2013 |
| Ifleet (UK) LLP | | 2008 |
| Ifleet Ltd | Administrative & support | 2008 |
| Ifocus Technologies Ltd | Information & communication | 2026 |
| Ifybella Complexcare Services Ltd | Health & social care | 2017 |
| Igas Energy Solutions Ltd | Construction | 2024 |
| Igas Solutions Ltd | Administrative & support | 2017 |
| Igcentric Limited | Information & communication | 2025 |
| Ightee Limited | Information & communication | 1995 |
| Ignatia Sensors Ltd | Manufacturing | 2018 |
| Igneus Limited | Construction | 2011 |
| Ignis Fire Doors Ltd | Manufacturing | 2021 |
| Ignis Solar Ltd | Construction | 2025 |
| Ignite Learning Limited | Education | 2023 |
| Ignite Management Services Limited | Administrative & support | 2020 |
| Ignite Tutoring Ltd | Education | 2021 |
| Ignitia Innovation Limited | Information & communication | 2025 |
| Igun Studio Ltd. | Information & communication | 2017 |
| IH Associates Limited | Professional & scientific | 2010 |
| IH Foods Services Ltd | Hospitality | 2026 |
| Ihbo Ltd | Real estate | 2021 |
| Iheartstickers Ltd | Wholesale & retail | 2023 |
| IHS Group Limited | Financial services | 2025 |
| IHS Property Investment Ltd | Real estate | 2022 |
| Ihsan Quality Consulting Ltd | Professional & scientific | 2025 |
| Iila the Label Limited | Wholesale & retail | 2024 |
| Iizzat Group Ltd | Real estate | 2024 |
| IJ Cars Services Ltd | Wholesale & retail | 2024 |
| IJA East Africa Safaris Limited | Hospitality | 2023 |
| IJJ Consulting Limited | Administrative & support | 2025 |
| IJT Enterprises Limited | Professional & scientific | 2006 |
| Ikan Facilities Management Limited | Administrative & support | 2011 |
| Ikan Services Ltd | Information & communication | 2023 |
| IKE Healthcare Ltd | Health & social care | 2023 |
| Ikenet Solutions and Consultancy Ltd | Information & communication | 2017 |
| Ikeposh Media Ltd | Information & communication | 2020 |
| Ikigai Camps Ltd | Administrative & support | 2023 |
| Ikigai Psychotherapy Ltd | Health & social care | 2023 |
| IKU Property Investment Limited | Real estate | 2025 |
| Ikudu Tutoring Ltd | Education | 2024 |
| IL Carpentry London Ltd | Other services | 2023 |
| IL Cerro LLP | | 2005 |
| Ilab Solutions Ltd | Administrative & support | 2014 |
| Ilarte Foods Ltd | Hospitality | 2019 |
| Ilarte Ltd | Information & communication | 2018 |
| Ilbsuk Ltd | Professional & scientific | 2025 |
| Ilearn London Ltd | Education | 2019 |
| Ilife PVT Ltd | Information & communication | 2017 |
| Ilkley Martial Arts Centre Ltd | Arts & recreation | 2024 |
| Illuminance Fostering Services Ltd | Health & social care | 2021 |