| Idiagnose Ltd | Education | 2022 |
| Ididit Health and Social Care Wellbeing Solutions Ltd | Health & social care | 2020 |
| Idigital Graphics Limited | Information & communication | 2014 |
| Idigital Investments Holdings Ltd | Financial services | 2020 |
| Idigital Investments Ltd | Professional & scientific | 2014 |
| Idigital NO. 1 Limited | Administrative & support | 2019 |
| Idigital NO. 2 Limited | Administrative & support | 2019 |
| Idigital Services Limited | Professional & scientific | 2015 |
| Idioteque Dreamers Limited | Extraterritorial | 2019 |
| Idle Bradford Limited | Health & social care | 2023 |
| Idle Gifts & Cards Limited | Wholesale & retail | 2026 |
| Idle Greengrocers Ltd | Wholesale & retail | 2025 |
| Idmac Consulting Ltd | Information & communication | 2013 |
| Idol State Limited | Professional & scientific | 2022 |
| IDP Investments Limited | Financial services | 2019 |
| IDQ Consulting Limited | Information & communication | 2026 |
| IDS Logic UK Limited | Information & communication | 2010 |
| IDS Properties Limited | Real estate | 2021 |
| IDS York Ltd | Construction | 2018 |
| Idukki Gold Tea and Spices Ltd | Manufacturing | 2025 |
| Idwtryd Ltd | Information & communication | 2025 |
| IDY V. Fit Naturals Ltd | Wholesale & retail | 2025 |
| Idylec Services Ltd | Construction | 2022 |
| Idyllic Properties (Spain) Limited | Hospitality | 2001 |
| Idyllic Properties Limited | Hospitality | 1995 |
| Idynamics Group Limited | Financial services | 2025 |
| Idynamics Limited | Information & communication | 1994 |
| IE Property Ventures Ltd | Real estate | 2026 |
| Ie&D Hurford Limited | Other services | 2003 |
| IEL Wampum Limited | Administrative & support | 2017 |
| Ienarac Ltd | Wholesale & retail | 2020 |
| Ieremia's Ltd | Transport & logistics | 2026 |
| Iesp Ltd | Real estate | 2022 |
| IF Imagined Limited | Professional & scientific | 2022 |
| IF IT IS Entertainment Limited | Information & communication | 2025 |
| IF UP North Ltd | Hospitality | 2013 |
| Ifarada Community Interest Company | Information & communication | 2023 |
| Ifcfa Limited | Other services | 2018 |
| IFF Digital Media Ltd | Professional & scientific | 2021 |
| Ifia Investments Ltd | Real estate | 2018 |
| Iftikhaar N Limited | Manufacturing | 2026 |
| Ify-Ann Beauty World Limited | Other services | 2025 |
| IG Development Holdings Limited | Financial services | 2019 |
| IG Evolution Ltd | Professional & scientific | 2024 |
| IG Investments (SRC) Limited | Professional & scientific | 2021 |
| IG Properties & Investment Ltd | Real estate | 2026 |
| Igaming Tracker Limited | Information & communication | 2016 |
| Igbo Progressive Community CIC | Administrative & support | 2018 |
| Igbo Union Yorkshire CIC | Education | 2020 |
| IGD Sport (Compression) Ltd | Wholesale & retail | 2018 |
| IGD Sport (Holdings) Ltd | Financial services | 2021 |
| IGD Sport (Merchandising) Ltd | Wholesale & retail | 2021 |
| IGD Sport Ltd | Arts & recreation | 2013 |
| Iglobal (UK) Limited | Wholesale & retail | 2013 |
| Igloo Group Ltd | Wholesale & retail | 2022 |
| Igloo Holdco Limited | Financial services | 2020 |
| Igloo Housing Limited | Real estate | 2013 |
| Igloo Properties Ltd | Construction | 2026 |
| Igloo Street Ltd | Real estate | 2016 |
| Igloo-Uk Ltd | Wholesale & retail | 2022 |
| Igloorefrigeration Ltd | Wholesale & retail | 2022 |
| Ignacy Construction Limited | Construction | 2025 |
| Ignatius Ltd | Real estate | 2017 |
| Igneous Solutions Ltd | Professional & scientific | 2020 |
| Ignis Suppression Ltd | Construction | 2023 |
| Ignite EV Charge Ltd | Manufacturing | 2025 |
| Ignite Futures Group LLP | | 2022 |
| Ignite Group Services Limited | Professional & scientific | 2021 |
| Ignite Immersive Education Ltd | Education | 2025 |
| Ignition Club Ltd | Wholesale & retail | 2026 |
| Ignition Pro - School for Entrepreneurs Ltd | Education | 2019 |
| Ignored Customer Limited | Information & communication | 2026 |
| Ignyte Software Limited | Information & communication | 2018 |
| Igoe Studio Ltd | Professional & scientific | 2025 |
| Igoris Logistics Ltd | Transport & logistics | 2015 |
| IGS Welding Limited | Manufacturing | 2017 |
| IGT Properties Ltd | Real estate | 2023 |
| Iguru Solutions Limited | Information & communication | 2014 |
| Igwe Afro Caribbean Stores Limited | Wholesale & retail | 2025 |
| IH Enterprises Hub Limited | Wholesale & retail | 2026 |
| IH Imports Limited | Transport & logistics | 2025 |
| IH Lettings Ltd | Real estate | 2025 |
| IH Transport Limited | Transport & logistics | 2020 |
| IHF75 Limited | Administrative & support | 2017 |
| IHK Property Investments Limited | Real estate | 2024 |
| Iholloway Solutions Ltd | Information & communication | 2021 |
| IHS Lothian Corporate Holdings Limited | Administrative & support | 2014 |
| IHS Lothian Corporate Limited | Administrative & support | 2014 |
| IHS Lothian Holdings Limited | Financial services | 2014 |
| IHS Lothian Investments Limited | Financial services | 2014 |
| IHS Services Ltd | Hospitality | 2019 |
| Ihsan Properties Limited | Real estate | 2026 |
| Ihsn Property Investments Ltd | Real estate | 2024 |
| Ihubrightdecor Ltd | Construction | 2025 |
| Ihuff Properties Ltd | Real estate | 2025 |
| IIB Consulting Ltd | Information & communication | 2018 |
| IIB Dena Nanotech Ltd | Manufacturing | 2012 |
| IIC (C&T) Limited | Administrative & support | 2004 |
| IIC (Leeds Schools) Fund Investment Limited | Administrative & support | 2005 |
| IIC Barnet Funding Investment Limited | Administrative & support | 2006 |