| Inkjet Prints Ltd | Manufacturing | 2022 |
| Inner Resources Psychotherapy Limited | Professional & scientific | 2021 |
| Inner Rhythm Ltd | Administrative & support | 2006 |
| Innermost Global Ltd | Information & communication | 2025 |
| Inniverse Ltd | Wholesale & retail | 2025 |
| Innomovate Management Consultants Ltd | Professional & scientific | 2024 |
| Innovateal Technology Services Ltd | Information & communication | 2025 |
| Innovative People Limited | Information & communication | 2025 |
| Innovative Plastering Limited | Construction | 2013 |
| Innovo Data LLP | | 2026 |
| Innoworld Limited | Wholesale & retail | 2017 |
| Inova Digital Solutions Ltd | Information & communication | 2025 |
| Inproperties Limited | Real estate | 2013 |
| Insight Interior Solutions Limited | Construction | 2010 |
| Inspire Nails Limited | Other services | 2022 |
| Instaderm Ltd | Health & social care | 2018 |
| Institute of Seamanship Community Interest Company | Professional & scientific | 2010 |
| Insync Technologies Limited | Information & communication | 2010 |
| Intact Accounting Limited | Professional & scientific | 2014 |
| Intact Tax Limited | Financial services | 2021 |
| Integrated Care West Limited | Health & social care | 2022 |
| Interface Travel (UK) Limited | Administrative & support | 2016 |
| Intergreen Limited | Wholesale & retail | 1993 |
| Interim Cosmetics Limited | Other services | 2004 |
| International Global Services (IGS) Ltd | Administrative & support | 2020 |
| International Immigration Limited | Professional & scientific | 2020 |
| International Messe Service Ltd | Professional & scientific | 2022 |
| Intevora Ltd | Construction | 2026 |
| Inti RAY Ltd | Construction | 2025 |
| Into the Meadow Limited | Wholesale & retail | 2022 |
| Introworld Technology Limited | Information & communication | 2009 |
| Intuit Wellbeing Limited | Wholesale & retail | 2019 |
| Invenzant Technologies Ltd | Information & communication | 2024 |
| Inverborne Limited | Administrative & support | 2018 |
| Invesco (Development) Limited | Real estate | 2006 |
| Invest in Time Ltd | Administrative & support | 2020 |
| Investment House International Limited | Construction | 2009 |
| Invictus Motors Limited | Wholesale & retail | 2017 |
| Invictus Porsche Ltd | Wholesale & retail | 2025 |
| Ioachim Carpentry Ltd | Manufacturing | 2025 |
| Ioana Profir Ltd | Transport & logistics | 2016 |
| ION Mironescu Ltd | Construction | 2020 |
| ION Paragina Ltd | Construction | 2014 |
| Ionut Iordache Transport Ltd | Transport & logistics | 2025 |
| Iony Transport Limited | Construction | 2025 |
| Iorga Driving Ltd | Wholesale & retail | 2017 |
| Iorgadraiving Ltd | Transport & logistics | 2026 |
| Iosif&Claudiu Limited | Construction | 2020 |
| IP Builders Brickwork Limited | Construction | 2015 |
| IP Builders Scaffolding Limited | Construction | 2024 |
| Ipca Capital Limited | Financial services | 2013 |
| Ipca Real Estate Limited | Real estate | 2015 |
| IPN Academy Limited | Professional & scientific | 2024 |
| IR Concepts Ltd | Wholesale & retail | 2021 |
| Iraq Morning Sun Ltd | Wholesale & retail | 2017 |
| Iris Vista Ltd | Real estate | 2024 |
| Ironcrest Dynamics Ltd | Administrative & support | 2026 |
| Ironside Greener Ltd | Professional & scientific | 2018 |
| Irregular Choice Limited | Professional & scientific | 2003 |
| Irvan Creative GB Limited | Professional & scientific | 2005 |
| IS Applied Intelligence Limited | Professional & scientific | 2026 |
| IS Shah Properties Ltd | Real estate | 2026 |
| ISA Design LAB Limited | Professional & scientific | 2016 |
| Isaac Florence Ltd | Administrative & support | 2010 |
| Isabel's Salon Limited | Other services | 2011 |
| Isabella Florists Online Ltd | Wholesale & retail | 2025 |
| Isakamazon Ltd | Transport & logistics | 2023 |
| Isek 145 Ltd | Real estate | 2020 |
| Isek Ltd | Real estate | 2019 |
| Ishaq & Irshan Ltd | Real estate | 2025 |
| Ishar Consulting Limited | Professional & scientific | 2023 |
| Ishisha Edgware Limited | Hospitality | 2017 |
| Ishq Tandoori Ltd | Hospitality | 2018 |
| Isisplace Limited | Wholesale & retail | 1996 |
| Iskcon Construction Limited | Construction | 2023 |
| Isla Pine Ltd | Wholesale & retail | 2025 |
| Isla Property Holdings Ltd | Real estate | 2024 |
| Islacare Ltd | Information & communication | 2019 |
| Islamic Solutions Ltd | Wholesale & retail | 2024 |
| Islands Spice Company Limited | Wholesale & retail | 2008 |
| Isle of Dogs Sushi Ltd | Hospitality | 2020 |
| Isover Limited | Professional & scientific | 2025 |
| Issai Teach Ltd | Education | 2021 |
| IT Home Solutions Ltd | Information & communication | 2021 |
| IT Pro Limited | Information & communication | 2007 |
| IT4UHELPDESK Limited | Information & communication | 2015 |
| Itali Limited | Professional & scientific | 2012 |
| Italia Domus Ltd | Wholesale & retail | 2019 |
| Italiahome Online Ltd | Wholesale & retail | 2021 |
| Italian Drilling Consultants Ltd | Wholesale & retail | 2010 |
| Italy Insight Ltd | Administrative & support | 2017 |
| Itaris Management Ltd | Real estate | 2023 |
| Itech Corporate Solutions Ltd | Information & communication | 2023 |
| Itlyst Limited | Information & communication | 2025 |
| ITM Europe Ltd | Information & communication | 2021 |
| Itod Ltd | Transport & logistics | 2017 |
| ITR Exhibitions Ltd | Wholesale & retail | 2025 |
| Itrade Solutions Ltd | Wholesale & retail | 2024 |
| Iuli Media Ltd | Professional & scientific | 2024 |
| Iulidan Construction Ltd | Construction | 2024 |