| Ibuyphones Ltd | Wholesale & retail | 2025 |
| IBZ Autoz Ltd | Wholesale & retail | 2025 |
| IC Roofing Limited | Construction | 2019 |
| ICA Bargain Ltd | Wholesale & retail | 2025 |
| Ice & Slice Restaurants Ltd | Hospitality | 2022 |
| Ice and Slice Events Ltd | Hospitality | 2026 |
| Ice Cream Alliance Limited(The) | Other services | 1944 |
| Ice Hotels Ltd | Hospitality | 2023 |
| Iceberg (Eco) Ltd | Agriculture & fishing | 2021 |
| Ickonic Enterprises Limited | Other services | 1998 |
| Ickonic Media Group Limited | Other services | 2019 |
| Iclean Community Car Wash Ltd | Administrative & support | 2025 |
| Iconia Investments Ltd | Real estate | 2024 |
| Iconic Store Ltd | Hospitality | 2022 |
| Iconic Transport INT Ltd | Transport & logistics | 2018 |
| Iconiq Ltd | Information & communication | 2017 |
| Icons Group Holdings Limited | Financial services | 2024 |
| Icons Talent Limited | Administrative & support | 2017 |
| Icreate Moments Ltd | Information & communication | 2023 |
| ICT Business Advice Ltd | Wholesale & retail | 2018 |
| ICT Green Ltd | Information & communication | 2013 |
| ICT Recycle Ltd | Information & communication | 2025 |
| ICT Technical Services Ltd | Information & communication | 2014 |
| ID Derby CIC | Education | 2024 |
| ID Travel Ltd | Transport & logistics | 2022 |
| ID Vehicle Solutions Limited | Wholesale & retail | 2019 |
| IDB Accountancy Limited | Professional & scientific | 2018 |
| IDB Rail Services Limited | Construction | 2019 |
| IDC One Limited | Financial services | 2019 |
| IDC Two Limited | Financial services | 2019 |
| Idcp Ltd | Professional & scientific | 2011 |
| Ideal Logistics U.K. Ltd | Transport & logistics | 2021 |
| Ideal RE & Movers Ltd | Transport & logistics | 2025 |
| Ideal Sweets Derby Ltd | Wholesale & retail | 2025 |
| IDEAS365 Ltd | Wholesale & retail | 2024 |
| Ideeal Flooring Ltd | Construction | 2026 |
| Identity Leader Development Ltd | Professional & scientific | 2023 |
| Idepat Consulting Limited | Information & communication | 2024 |
| Idol Technology Ltd | Information & communication | 2016 |
| Idreece Ltd | Transport & logistics | 2019 |
| Ie-Design (London) Limited | Construction | 2017 |
| Ieducate Ltd | Real estate | 2016 |
| Ifedapoige Ltd | Health & social care | 2023 |
| Iflorj Healthcare Ltd | Health & social care | 2023 |
| Ifox Trading Ltd | Other services | 2014 |
| Iframe Services Limited | Information & communication | 2015 |
| Iftikhar Plastic & Company UK Ltd | Wholesale & retail | 2020 |
| IG Consultancy Holdings Ltd | Professional & scientific | 2021 |
| IGC Property Limited | Real estate | 2019 |
| Igfsa Limited | Real estate | 2026 |
| IGN Projects Ltd | Financial services | 2025 |
| Ignite (Grantham) Limited | Wholesale & retail | 2010 |
| Ignite (North) Limited | Wholesale & retail | 2013 |
| Ignite Blue Limited | Other services | 2024 |
| Ignt Store Ltd | Wholesale & retail | 2021 |
| Igor Trans Express Limited | Transport & logistics | 2017 |
| IGT Property Services Ltd | Hospitality | 2021 |
| IH Academy Limited | Education | 2025 |
| IH Building Works Ltd | Construction | 2025 |
| Ihefeny Ltd | Information & communication | 2015 |
| IHN Asset Holdings Limited | Real estate | 2022 |
| IHS Training Ltd | Education | 2025 |
| Ihsan Pharma (East Grinstead) Ltd | Wholesale & retail | 2025 |
| Ihsan Pharma Group Ltd | Financial services | 2025 |
| Ihsan Pharma Ltd | Wholesale & retail | 2016 |
| II Consulting Ltd | Information & communication | 2011 |
| IJA Commercial Limited | Construction | 2017 |
| IJD Confectionary Ltd | Manufacturing | 2025 |
| IJD2 Confectionary Ltd | Manufacturing | 2026 |
| IK Adas Dynamic Radar Calibration Ltd | Manufacturing | 2021 |
| Ikhlas Education Centre Limited | Education | 2009 |
| Ikla Ltd | Construction | 2023 |
| Ikld Ltd | Health & social care | 2015 |
| IKM Accountants Ltd | Professional & scientific | 2020 |
| Ikos Consulting UK Limited | Professional & scientific | 1997 |
| Ikos Property Investments Ltd | Real estate | 2026 |
| IKP Convenience Store Private Limited | Real estate | 2024 |
| IKP Group Limited | Real estate | 2024 |
| IKP Health Ltd | Health & social care | 2025 |
| IKP Limited | Real estate | 2025 |
| Iktravel Ltd | Transport & logistics | 2026 |
| Ikube Holding Ltd | Financial services | 2020 |
| Ikube Limited | Information & communication | 2017 |
| Ikube Property Services Ltd | Real estate | 2020 |
| IL Building Services Ltd | Construction | 2019 |
| Iledna Limited | Information & communication | 2012 |
| Ilkeston Community Boxing Club Limited | Education | 2025 |
| Illumineatre Ltd | Arts & recreation | 2025 |
| Illusconnex Ltd | Real estate | 2021 |
| Ilos Accounts Ltd | Professional & scientific | 2023 |
| ILR Homes Ltd | Real estate | 2021 |
| ILS Automotive and Logistics Limited | Wholesale & retail | 2026 |
| ILW Consultancy Ltd | Information & communication | 2015 |
| Imagewise Ltd | Health & social care | 2024 |
| Imago Estates Ltd | Real estate | 2020 |
| Imansky Consulting Ltd | Professional & scientific | 2024 |
| Imansky Investments Ltd | Real estate | 2024 |
| Imbue Ventures Limited | Education | 2023 |
| IMG Print Management Ltd | Manufacturing | 2022 |
| IMH Homes Limited | Real estate | 2017 |