| IIC Barnet Holding Company Limited | Administrative & support | 2005 |
| IIC Barnet Subdebt Limited | Administrative & support | 2006 |
| IIC Bristol Funding Investment Limited | Administrative & support | 2006 |
| IIC Bristol Infrastructure Limited | Administrative & support | 2006 |
| IIC Bristol Subdebt Limited | Administrative & support | 2006 |
| IIC by Education (Peterborough Schools) Limited | Administrative & support | 2005 |
| IIC Enfield Funding Investment Limited | Administrative & support | 2006 |
| IIC Enfield Holding Company Limited | Administrative & support | 2006 |
| IIC Enfield Subdebt Limited | Administrative & support | 2006 |
| IIC Lambeth Funding Investment Limited | Administrative & support | 2005 |
| IIC Lambeth Holding Company Limited | Administrative & support | 2005 |
| IIC Lambeth Subdebt Limited | Administrative & support | 2005 |
| IIC Northampton (Pendereds) Limited | Professional & scientific | 2007 |
| IIC Northampton Funding Investment Limited | Administrative & support | 2006 |
| IIC Northampton Holding Company Limited | Administrative & support | 2006 |
| IIC Northampton Limited | Administrative & support | 2005 |
| IIC Northampton Subdebt Limited | Administrative & support | 2006 |
| IIC Peterborough Funding Investment Limited | Administrative & support | 2006 |
| IIC Peterborough Holding Company Limited | Administrative & support | 2006 |
| IIC Peterborough Subdebt Limited | Administrative & support | 2006 |
| IIC Redcar and Cleveland Funding Investment Limited | Administrative & support | 2007 |
| IIC Redcar and Cleveland Holding Company Limited | Administrative & support | 2007 |
| IIC Redcar and Cleveland Subdebt Limited | Administrative & support | 2007 |
| Iiza Suites Ltd | Real estate | 2026 |
| IJ Estates Ltd Ltd | Real estate | 2023 |
| IJ Flight Training Limited | Education | 2024 |
| Ijatta Limited | Real estate | 2010 |
| IJC Property Limited | Real estate | 2020 |
| IJC Tech Ltd | Water & waste | 2026 |
| IJF Property Limited | Real estate | 2024 |
| Ijgb Entertainment Ltd | Arts & recreation | 2025 |
| IJI Rapid Tread Ltd | Wholesale & retail | 2026 |
| Ijjaz Irtiza Ltd | Transport & logistics | 2026 |
| IJP Consulting Limited | Information & communication | 2007 |
| IJR Talent Limited | Wholesale & retail | 2024 |
| IK POL Transport Ltd | Transport & logistics | 2026 |
| IKE Choice Couture Limited | Wholesale & retail | 2019 |
| Ikemproperties Ltd | Real estate | 2026 |
| Iken Associates Ltd | Professional & scientific | 2001 |
| Ikense Ltd | Wholesale & retail | 2023 |
| IKH Healthcare Ltd | Other services | 2021 |
| Ikigai Property Solutions Limited | Real estate | 2025 |
| Ikigai Tech 2 Limited | Information & communication | 2018 |
| IKK Lets Ltd | Hospitality | 2026 |
| IKO Supplies Ltd | Wholesale & retail | 2023 |
| Ikonix Telecoms Limited | Information & communication | 2006 |
| Ikrk Limited | Financial services | 2025 |
| Iksu Global Limited | Wholesale & retail | 2024 |
| IKX Consulting Ltd | Professional & scientific | 2023 |
| IL Bosco Ltd | Hospitality | 2023 |
| IL Magnifico Limited | Real estate | 2018 |
| IL Mantovano Limited | Hospitality | 2009 |
| IL Piatto Leeds Limited | Hospitality | 2023 |
| IL Sogno Ltd | Hospitality | 2019 |
| Ilans Investments Ltd | Real estate | 2025 |
| Ilas Healthcare Ltd | Professional & scientific | 2024 |
| ILB Holdings Ltd | Hospitality | 2019 |
| Ileaf Systems Limited | Agriculture & fishing | 2021 |
| Ilia Holdings Ltd | Financial services | 2026 |
| Ilia Properties Ltd | Real estate | 2024 |
| Iliad Group Limited | Wholesale & retail | 2024 |
| Iliad Solutions Limited | Information & communication | 2001 |
| Iliadis Locum Services Ltd | Wholesale & retail | 2025 |
| Iliahomes Ltd | Real estate | 2026 |
| Ilightthat Ltd | Wholesale & retail | 2024 |
| ILK Agency Holdings Ltd | Professional & scientific | 2017 |
| ILK Agency Ltd | Professional & scientific | 2007 |
| ILK Group Limited | Professional & scientific | 2020 |
| Ilkley Care Associates Ltd. | Health & social care | 1993 |
| Ilkley Developments Limited | Real estate | 2003 |
| Ilkley Floor Care Limited | Wholesale & retail | 2010 |
| Ilkley Vision Limited | Wholesale & retail | 2025 |
| ILL Group Ltd | Professional & scientific | 2025 |
| Illingworth and Comstive Limited | Construction | 1973 |
| Illingworth Supplies Limited | Wholesale & retail | 1987 |
| Illumina Education Ltd | Education | 2025 |
| Illuminate Psychology Limited | Health & social care | 2025 |
| Illuminate Wealth Management Ltd | Financial services | 2019 |
| Illuminous Brewing Limited | Extraterritorial | 2020 |
| Illy's Barber Ltd | Other services | 2025 |
| ILM Law Ltd | Professional & scientific | 2020 |
| Ilmarin Limited | Administrative & support | 2010 |
| ILS24HEALTH Care Limited | Health & social care | 2013 |
| ILT Events Limited | Administrative & support | 2020 |
| Iluminara | Financial services | 2024 |
| IM and FI Investments Ltd | Real estate | 2024 |
| Imaan & Anayah Limited | Health & social care | 2016 |
| Imab Healthcare Ltd | Financial services | 2025 |
| Imageco Holdings Limited | Professional & scientific | 2014 |
| Imageco Visual Imaging Limited | Manufacturing | 2000 |
| Imagent Limited | Health & social care | 2021 |
| Images Stock GB Ltd | Wholesale & retail | 2010 |
| Imaginary Jargon Ltd | Information & communication | 2025 |
| Imagine Asset Finance Limited | Financial services | 2019 |
| Imagine Universe CIC | Manufacturing | 2019 |
| Imaging 2 Intervention Limited | Health & social care | 2019 |
| Imaging to Sort Limited | Health & social care | 2026 |
| Imani Sweet Treats Ltd | Wholesale & retail | 2022 |
| Imarket Ltd | Information & communication | 2021 |
| Imarketing Solutions Ltd | Professional & scientific | 2020 |