| Investin USA Limited | Real estate | 2013 |
| Investinjersey (Bristol Street) Limited | Real estate | 2010 |
| Invicta Partnership Limited | Administrative & support | 2021 |
| Invytr Limited | Information & communication | 2017 |
| ION Communications Limited | Information & communication | 2013 |
| IOT Data Ltd | Information & communication | 2021 |
| IP Centrum Annuities Limited | Professional & scientific | 2013 |
| IP Centrum Global Services Limited | Extraterritorial | 2014 |
| IP Centrum Group Limited | Financial services | 2014 |
| IP Centrum Limited | Professional & scientific | 2009 |
| IPC Renewals Limited | Extraterritorial | 2014 |
| IPC Technologies Limited | Extraterritorial | 2014 |
| IPG Automotive UK Limited | Professional & scientific | 2018 |
| IPP Education Limited | Professional & scientific | 1998 |
| IQ Partnership Limited | Administrative & support | 2010 |
| Iqbal Prime Properties Limited | Real estate | 2022 |
| Iqbal Properties Limited | Real estate | 2019 |
| Iqbal Property Investments Limited | Real estate | 2020 |
| Iqbino Software Limited | Information & communication | 2024 |
| IQZ Limited | Health & social care | 2018 |
| Irbis Capital Partners Limited | Administrative & support | 2023 |
| Ireland Property Ventures Ltd | Real estate | 2026 |
| Iris Inspirations Ltd | Education | 2024 |
| Irise Horizon Ltd | Real estate | 2025 |
| Irkla Brothers Ltd | Wholesale & retail | 2026 |
| IRM Plumbing Ltd | Construction | 2024 |
| Iron Stone Place Management Company Limited | Households | 2019 |
| Ironstone Capital Limited | Financial services | 2023 |
| IRV Aesthetics Limited | Health & social care | 2019 |
| Irving Systems Ltd | Information & communication | 2004 |
| IS Bhohie Limited | Health & social care | 2014 |
| Isaac Property Management Ltd | Professional & scientific | 2022 |
| Isaiah Oldbury Limited | Extraterritorial | 1985 |
| Isamy Estates Ltd | Real estate | 2024 |
| Isdel Energy Limited | Administrative & support | 2017 |
| Iseg Limited | Financial services | 2016 |
| Ishaji Properties Ltd | Administrative & support | 2018 |
| Isis Property Group Limited | Financial services | 2023 |
| Isis Property Lettings Limited | Real estate | 2023 |
| Isis Property Sales Limited | Real estate | 2023 |
| Isla Vida Beauty & Aesthetics Ltd | Health & social care | 2018 |
| Islamic Divorces Ltd | Other services | 2025 |
| Isle of Wight Holiday Homes Limited | Extraterritorial | 2019 |
| ISM Limited | Arts & recreation | 1992 |
| Ismay Property Solutions Ltd | Real estate | 2016 |
| Isnuug Ltd | Administrative & support | 2025 |
| Isobel Higgins Limited | Professional & scientific | 2003 |
| Isoft Testing Ltd | Information & communication | 2021 |
| Isolab Limited | Manufacturing | 2021 |
| Isotech Solutions Ltd | Information & communication | 2025 |
| Isra Global Ltd | Professional & scientific | 2023 |
| Issak Ltd | Other services | 2022 |
| Istiophorus LLP | | 2024 |
| Isuzu (UK) Limited | Wholesale & retail | 1986 |
| IT Stream Limited | Information & communication | 2024 |
| It's a Wrap Car Care Limited | Wholesale & retail | 2019 |
| Itala Limited | Professional & scientific | 1999 |
| Item Registry Ltd | Information & communication | 2020 |
| ITK Training Ltd | Education | 2025 |
| Itsa Digital Tax Ltd | Professional & scientific | 2026 |
| Itsl Management Limited | Administrative & support | 1970 |
| It’S Lahore Ltd | Hospitality | 2026 |
| Iuvo Limited | Information & communication | 1998 |
| Ivaehu Creative Ltd | Wholesale & retail | 2020 |
| Ivita Ltd | Health & social care | 2020 |
| Ivor Carter Consultancy Services Ltd | Professional & scientific | 2022 |
| Ivory Tower Bridal Couture Limited | Wholesale & retail | 2004 |
| IVY Mews Management Company Limited | Households | 2004 |
| Iwcam Limited | Real estate | 2021 |
| Ixcloud Limited | Information & communication | 2024 |
| Izfa Group Ltd | Real estate | 2025 |
| Izla Technologies Limited | Information & communication | 2024 |
| Izzy and Emily Properties Ltd | Real estate | 2026 |
| J & I Catering Limited | Hospitality | 2021 |
| J & J Fabrications Limited | Manufacturing | 2025 |
| J & M Property (Birmingham) Ltd | Real estate | 2024 |
| J & S Oral Health Care Ltd | Health & social care | 2012 |
| J & S Properties (B'Ham) Ltd | Real estate | 2018 |
| J & V Kelly Limited | Mining & quarrying | 1997 |
| J a & a J Rose Properties Limited | Construction | 2013 |
| J a Brown Building Solutions Ltd | Administrative & support | 2015 |
| J a FOX Properties Limited | Real estate | 2021 |
| J a Health Solutions Ltd | Health & social care | 2018 |
| J a Ridley & Sons Limited | Manufacturing | 1988 |
| J Alexander Contractors Ltd. | Other services | 2016 |
| J Broad Limited | Other services | 2025 |
| J C L Wills & Estate Planning Limited | Professional & scientific | 2025 |
| J C R Solutions Limited | Construction | 2008 |
| J Cardin Holdings Limited | Financial services | 2026 |
| J Castle Construction Ltd | Construction | 2019 |
| J Chagger Pharm Ltd | Health & social care | 2013 |
| J D Brickwork Contractors Ltd | Construction | 2023 |
| J Daly & Sons Building Contractors Limited | Construction | 2000 |
| J Evans Property Developments Ltd | Construction | 2023 |
| J FAY Plastering Ltd | Construction | 2020 |
| J G Flooring Limited | Construction | 2015 |
| J G Sharkey Limited | Construction | 2011 |
| J Holland Construction Limited | Construction | 2014 |
| J L Automotive Limited | Wholesale & retail | 2016 |
| J M V Excavations Ltd. | Construction | 1997 |