| Ibioshield Limited | Manufacturing | 2021 |
| Ibookbinding Ltd | Manufacturing | 2023 |
| Ibrar Syed Ltd | Transport & logistics | 2025 |
| Icarus Court Management Company Limited | Households | 1995 |
| Ice (London) Limited | Professional & scientific | 2009 |
| Ice Global Contracts Limited | Administrative & support | 2008 |
| Ice-Cubes.Org Ltd | Hospitality | 2008 |
| Ichiban 3BZ Ltd | Hospitality | 2020 |
| Icon Hairdresser Limited | Other services | 2022 |
| Iconicmantras Limited | Wholesale & retail | 2025 |
| ICQ Management Ltd | Extraterritorial | 2014 |
| Ideal Settings Limited | Wholesale & retail | 2023 |
| Ideaology Ltd | Real estate | 2015 |
| Idenias Ltd | Professional & scientific | 2012 |
| Idiots Guide to SEO Ltd | Information & communication | 2025 |
| Idlecombe Limited | Real estate | 2026 |
| IDP Holding Ltd | Information & communication | 2012 |
| IGJ Property Limited | Real estate | 2020 |
| Ignite Social Enterprise LP | | 2013 |
| Igo-To-Market Ltd | Professional & scientific | 2016 |
| IHC Hotel Limited | Professional & scientific | 1988 |
| IHC MAY Fair Hotel Limited | Professional & scientific | 1988 |
| IHC Overseas (U.K.) Limited | Professional & scientific | 1988 |
| IHG Hotels Limited | Administrative & support | 1995 |
| IHG PS Nominees Limited | Professional & scientific | 2009 |
| IHG UK Leased Hotels Limited | Hospitality | 2018 |
| Ihuoma Limited | Manufacturing | 2021 |
| Iinskin Limited | Health & social care | 2014 |
| Ilaa Properties Limited | Real estate | 2020 |
| Ilift Material Handling Ltd | Wholesale & retail | 2020 |
| Ilion Property Ltd | Agriculture & fishing | 2025 |
| Illingworth Mortgages Limited | Financial services | 2013 |
| Illingworth Runnymede Limited | Professional & scientific | 2014 |
| Illume Analytical Limited | Professional & scientific | 2023 |
| Illustrious Inns Limited | Hospitality | 2018 |
| Imagine a Beautiful Life Ltd | Financial services | 2023 |
| Imca Highway Services Ltd | Construction | 2018 |
| Imcp Limited | Professional & scientific | 2015 |
| Immersive Cloud Solutions Group Ltd | Information & communication | 2024 |
| Imperial Acre Estates Limited | Real estate | 1999 |
| Imperial Court Residents Limited | Households | 1984 |
| Imperial House (Epsom) Management Company Limited | Households | 2020 |
| Imperial Property Maintenance Limited | Construction | 2007 |
| Impira Limited | Professional & scientific | 2024 |
| Impulsion Matters Ltd | Agriculture & fishing | 2018 |
| Inception Pro Ltd | Administrative & support | 2022 |
| Inceptua Limited | Wholesale & retail | 2011 |
| Indelibly Limited | Wholesale & retail | 2023 |
| Indelibly Retail Ltd | Wholesale & retail | 2024 |
| Independent Film Festival & Awards Siffa UK Limited | Information & communication | 2016 |
| Indiana Greene Limited | Information & communication | 2024 |
| Indie Rabble Ltd | Manufacturing | 2022 |
| Indigina Technologies Limited | Information & communication | 2007 |
| Indigo Compass Ltd | Wholesale & retail | 2021 |
| Indigo Park (Chichester) Management Company Limited | Households | 2022 |
| Infinite Accountants Limited | Professional & scientific | 2014 |
| Infinite Trading Limited | Information & communication | 2018 |
| Infynet Ltd | Construction | 2026 |
| Ingliston Management Limited | Real estate | 2008 |
| Inner Glow by the IV Girls Ltd | Health & social care | 2026 |
| Innovation for Impact Ltd | Professional & scientific | 2011 |
| Innovatus Holdings Ltd | Professional & scientific | 2017 |
| Inovative Solutions UK Limited | Information & communication | 2010 |
| Inside to Outside and Beyond Limited | Health & social care | 2017 |
| Insight Avenue Ltd | Professional & scientific | 2016 |
| Insite Structures Ltd | Construction | 2021 |
| Insparise Ltd. | Administrative & support | 2013 |
| Inspire Consulting UK Limited | Professional & scientific | 2005 |
| INSPIRE4GROWTH Limited | Administrative & support | 2024 |
| Inspired Glazing Limited | Construction | 2019 |
| Instinqt Limited | Information & communication | 2015 |
| INT Group Limited | Professional & scientific | 2014 |
| INT Research Limited | Administrative & support | 2005 |
| INT2MED Limited | Manufacturing | 2009 |
| Integral Relocation Ltd | Real estate | 2020 |
| Integrated Sustainable Living Limited | Construction | 2021 |
| Integration Guys Ltd | Information & communication | 2023 |
| Intellection Business Intelligence Limited | Information & communication | 2009 |
| Intellego Education Partners UK Limited | Financial services | 2024 |
| Intelligent Home Technology+ Ltd | Wholesale & retail | 2018 |
| Intercontinental (PB) 1 | Professional & scientific | 2008 |
| Intercontinental (PB) 3 Limited | Professional & scientific | 2009 |
| Intercontinental Hotels Group Healthcare Trustee Limited | Administrative & support | 1995 |
| Intercontinental Hotels Group PLC | Hospitality | 2004 |
| Intercontinental Hotels Group Services Company | Other services | 1956 |
| Intercontinental Hotels Limited | Administrative & support | 2002 |
| Interior Profiles Limited | Administrative & support | 2004 |
| International Corporate Management Academy Ltd | Information & communication | 2025 |
| International Equipment Distributors Limited | Manufacturing | 2004 |
| International Network Supplies Group Ltd | Information & communication | 2017 |
| International Network Supplies Holdings Limited | Financial services | 2024 |
| Intervas Limited | Information & communication | 2006 |
| Intrusion Productions Ltd | Manufacturing | 2003 |
| Invalleon Limited | Financial services | 2025 |
| Inver Retail Ltd | Wholesale & retail | 2019 |
| Investams Limited | Construction | 2014 |
| Invicta Staffing Ltd | Administrative & support | 2014 |
| Invision Interiors Limited | Construction | 2024 |
| IP Cafe Ltd | Hospitality | 2019 |
| IP Renewals Group Limited | Information & communication | 2025 |