| International Student Accommodation Limited | Real estate | 2010 |
| International Supermarket Fruits & Vegetables Limited | Wholesale & retail | 2021 |
| International Support Company for Trade and Services Ltd | Wholesale & retail | 2025 |
| International Syndicate of Health and Aesthetic Services Workers and Psychotherapists and Special Education Specialists Ltd | Education | 2026 |
| International Venue Limited | Arts & recreation | 2008 |
| Interpid Care & Support Limited | Administrative & support | 2017 |
| Interpid Group Limited | Health & social care | 2024 |
| Interplus Ltd | Professional & scientific | 2020 |
| Intersat (UK) Ltd | Information & communication | 2005 |
| Interscape Interiors Limited | Construction | 2018 |
| Interstellar Academy Limited | Education | 2019 |
| Interstellar Corp Ltd | Real estate | 2023 |
| Interstellar Managed Investments Limited | Other services | 2019 |
| Intersyncmedia Ltd | Professional & scientific | 2025 |
| Intervent Cardio Ltd | Manufacturing | 2024 |
| Intervention Ltd | Hospitality | 2008 |
| Interweb UK Consulting Ltd | Information & communication | 2019 |
| Interxport Ltd | Wholesale & retail | 2018 |
| Interzone Property Management Ltd | Real estate | 2017 |
| Interzone Wealth Management Limited | Financial services | 2014 |
| Intext Systems Limited | Construction | 2011 |
| Intimate Apparel Digital UK Limited | Wholesale & retail | 2020 |
| Intimite Risk Consultancy Ltd | Information & communication | 2014 |
| Intouch Mortgage Services Ltd | Financial services | 2020 |
| Intrepid Media Ltd | Information & communication | 2006 |
| Intrinsic Works Ltd | Manufacturing | 2018 |
| Intro Sales Limited | Wholesale & retail | 2019 |
| Intrusted Pension Services Ltd | Financial services | 2020 |
| Intu Green Energy Limited | Construction | 2023 |
| Intumescent Chemicals Ltd | Professional & scientific | 2010 |
| Inunet Solutions Ltd | Information & communication | 2013 |
| Invella Associates Limited | Professional & scientific | 2016 |
| Invenna Limited | Information & communication | 2024 |
| Invent Learning Ltd | Education | 2019 |
| Invent Training Ltd | Education | 2021 |
| Inventive Ingredients Ltd | Wholesale & retail | 2007 |
| Inventoree.Io Ltd | Information & communication | 2024 |
| Invest Johal Ltd | Financial services | 2025 |
| Invest One Limited | Real estate | 2021 |
| Invest Sage Ltd | Financial services | 2023 |
| Invest Singla Ltd | Financial services | 2025 |
| Investabrix Ltd | Real estate | 2021 |
| Investco Dingley Limited | Construction | 2023 |
| Invested Group Limited | Construction | 2024 |
| Investica Finance Ltd | Administrative & support | 2025 |
| Investment Alliance Group Limited | Financial services | 2023 |
| Investment Alliance Ltd | Financial services | 2004 |
| Investment Boss Limited | Real estate | 2020 |
| Investment Consolidations Ltd | Other services | 2018 |
| Investmentproperties.Co.Uk Limited | Real estate | 1993 |
| Investmys Limited | Real estate | 2017 |
| Investoor Limited | Real estate | 2021 |
| Investzilla Ltd | Real estate | 2022 |
| Invicta Education Limited | Extraterritorial | 2014 |
| Invicta Point of Sale Limited | Extraterritorial | 2014 |
| Invicta Universal Limited | Real estate | 2002 |
| Invictus Electrical Ltd | Construction | 2022 |
| Invictus Health Group Ltd | Professional & scientific | 2026 |
| Invictus Organisation Ltd | Administrative & support | 2023 |
| Invincible 1 Ltd | Transport & logistics | 2026 |
| Inviso Building Surveying and Energy Assessment Limited | Construction | 2009 |
| Invito Services Limited | Information & communication | 2023 |
| Invonex Healthcare Limited | Health & social care | 2022 |
| Invonex Housing Limited | Real estate | 2016 |
| Invonex Limited | Wholesale & retail | 2011 |
| Invonex Properties Limited | Real estate | 2015 |
| Inwood Construction Ltd | Construction | 2022 |
| Inxs 1 Ltd | Manufacturing | 2017 |
| Inza Catering Ltd | Hospitality | 2024 |
| IOA Capital Limited | Financial services | 2025 |
| Iodi Private Limited | Wholesale & retail | 2022 |
| ION Animation Limited | Information & communication | 2014 |
| Ionel Limited | Transport & logistics | 2014 |
| Ionic Technologies International Limited | Professional & scientific | 2016 |
| Ioups Limited | Information & communication | 2025 |
| IP by Design Ltd | Professional & scientific | 2010 |
| IP Land Investment Ltd | Real estate | 2025 |
| IP Trustees Ltd | Financial services | 2020 |
| IPA Consulting Ltd | Information & communication | 2019 |
| Ipbb Properties Ltd | Real estate | 2022 |
| Iplan Consulting Limited | Financial services | 2011 |
| IPR Property Services Limited | Other services | 2015 |
| Iprovide Ltd | Wholesale & retail | 2025 |
| IPS (Coventry) Limited | Wholesale & retail | 2017 |
| IPS Couriers Limited | Transport & logistics | 2021 |
| IPS Property Services Limited | Real estate | 2025 |
| Ipswich Care Solutions Limited | Health & social care | 2014 |
| IQ Catering Ltd | Hospitality | 2025 |
| Iqbal Accounting Services Ltd | Professional & scientific | 2019 |
| Iqbal Driving Academy Ltd. | Education | 2021 |
| Iqbal Umar Ltd | Wholesale & retail | 2023 |
| Iqon Automotive Ltd | Wholesale & retail | 2023 |
| Iqon Investment Ltd | Wholesale & retail | 2017 |
| Iqra Infotech Ltd | Wholesale & retail | 2019 |
| Iqra Noor Estates Limited | Real estate | 2025 |
| Iqra Trading Investments Limited | Wholesale & retail | 2019 |
| Iqra Trading Limited | Wholesale & retail | 2020 |
| Ir-Taxi Limited | Transport & logistics | 2018 |
| Ir.Medical Ltd | Health & social care | 2025 |
| Iraad Taxis Ltd | Transport & logistics | 2019 |