| Infinity Lettings (Midlands) Ltd | Real estate | 2024 |
| Influential Developments Limited | Transport & logistics | 2019 |
| Infofrenz Techops Ltd | Information & communication | 2018 |
| Inforica Ltd | Information & communication | 2014 |
| Inheris Limited | Real estate | 2025 |
| Initial Care Services (ICS) Limited | Administrative & support | 2017 |
| Injenius Artificial Intelligence Limited | Manufacturing | 2025 |
| Injenius Bike International Ltd | Manufacturing | 2023 |
| Injenius Group International Limited | Professional & scientific | 2023 |
| Inn-Vogue Limited | Wholesale & retail | 2013 |
| Innovation Holdings Ltd | Financial services | 2022 |
| Insane Buildings Ltd | Professional & scientific | 2023 |
| Insane Urban Scents Ltd | Wholesale & retail | 2022 |
| Insight Management Academy Limited | Professional & scientific | 2012 |
| Inspiratech 2000 Limited | Professional & scientific | 2000 |
| Inspire Technology Limited | Wholesale & retail | 2009 |
| Inspired Dreams Limited | Professional & scientific | 2007 |
| Inspired Services Limited | Professional & scientific | 2001 |
| Inspirehaus Limited | Wholesale & retail | 2026 |
| Inspirengage Limited | Administrative & support | 2011 |
| Install Direct Ltd | Construction | 2024 |
| Install Fit UK Limited | Construction | 2024 |
| Instant Information Systems Ltd | Professional & scientific | 2011 |
| Insuraswap Ltd | Information & communication | 2023 |
| Insureworks Ltd | Information & communication | 2025 |
| Intapart Limited | Extraterritorial | 2005 |
| Intec Business Colleges Limited | Education | 1990 |
| Integral Machine Tool Services LLP | | 2008 |
| Integrated Doorset Solutions Limited | Manufacturing | 2014 |
| Integrated Gown and Glove Solutions Limited | Manufacturing | 2025 |
| Integrum SPV 21004 Limited | Energy | 2022 |
| Integrum SPV 21014 Limited | Energy | 2022 |
| Integrum SPV 22029 Limited | Energy | 2022 |
| Integrum SPV 22051 Limited | Energy | 2024 |
| Integrum SPV 22153 Limited | Energy | 2023 |
| Integrum SPV 22298 Limited | Energy | 2022 |
| Integrum SPV 22451 Limited | Energy | 2023 |
| Integrum SPV 22455 Limited | Energy | 2022 |
| Integrum SPV 22566 Limited | Energy | 2023 |
| Integrum SPV 22571 Limited | Energy | 2023 |
| Integrum SPV 22790 Limited | Energy | 2024 |
| Integrum SPV 23101 Limited | Energy | 2024 |
| Integrum SPV 24002 Limited | Energy | 2024 |
| Intelligent Wills & Probate Ltd | Professional & scientific | 2015 |
| Intellitrend Ltd. | Information & communication | 2021 |
| Intent Services Limited | Professional & scientific | 2020 |
| Interface Farm Enterprises Limited | Manufacturing | 1993 |
| Interface Limited | Manufacturing | 1968 |
| Intergana Limited | Transport & logistics | 2017 |
| Interior Design Journey Ltd | Real estate | 2023 |
| Intermediate Technology Development Group Limited | Professional & scientific | 1971 |
| Intermediate Technology Publications Limited | Professional & scientific | 2007 |
| International Commissioning Management Ltd | Information & communication | 2024 |
| Intisar AI Ltd | Professional & scientific | 2025 |
| Intractābilis Limited | Information & communication | 2025 |
| Intu Fire Compliance Ltd | Public administration | 2026 |
| Intuative Styling Ltd | Professional & scientific | 2011 |
| INU Catering Ltd | Hospitality | 2026 |
| Invest in YOU Therapy Limited | Health & social care | 2024 |
| Investcorp Global Limited | Administrative & support | 2012 |
| Inwoods Park Limited | Real estate | 2022 |
| Ioan Civil Engineering Consulting Ltd | Construction | 2024 |
| Ionesei Limited | Transport & logistics | 2025 |
| Ions Investment Ltd | Transport & logistics | 2022 |
| Ionut Boby Ltd | Transport & logistics | 2019 |
| Ionut Toma Limited | Transport & logistics | 2017 |
| IP Construction (Rugby) Limited | Construction | 2006 |
| IPA - Impex Limited | Administrative & support | 2008 |
| Ipet Limited | Professional & scientific | 2014 |
| Iplt Property Rental Ltd | Real estate | 2025 |
| IQ Medical 2025 Limited | Health & social care | 2019 |
| IQ Medical Limited | Manufacturing | 2008 |
| Iris IOT Solutions Limited | Information & communication | 2017 |
| Irlik Ltd | Transport & logistics | 2014 |
| Isabel Davies Ltd | Information & communication | 2025 |
| Isac Logistics Ltd. | Transport & logistics | 2017 |
| Isarg Limited | Information & communication | 2015 |
| ISB Rugby Ltd | Construction | 2023 |
| IT Management Consultancy Services Limited | Professional & scientific | 2017 |
| ITS Time Rugby Ltd | Manufacturing | 2021 |
| Ivane on Rails Ltd | Information & communication | 2024 |
| Ivory Keys Ltd | Hospitality | 2025 |
| IVY Grange (Bilton) Management Company Limited | Households | 2005 |
| IW Hatfield Ltd | Real estate | 2025 |
| Iwan Training Ltd | Information & communication | 2024 |
| Iworld Limited | Information & communication | 2010 |
| Ixbcc Ltd. | Professional & scientific | 2022 |
| Izhaan Limited | Hospitality | 2025 |
| J & Jarvis Enterprises Ltd | Financial services | 2023 |
| J & L Coppard Minex Limited | Mining & quarrying | 2016 |
| J & M Rowbottom Limited | Real estate | 2020 |
| J & R Gerry Ltd | Wholesale & retail | 2023 |
| J a B Training & Consultancy Limited | Education | 2022 |
| J a Walters Limited | Professional & scientific | 2003 |
| J and J Carpentry LLP | | 2026 |
| J B C International Ltd | Transport & logistics | 2023 |
| J Beck Contracts Limited | Construction | 2023 |
| J Burgess Contracting Limited | Administrative & support | 2011 |
| J C R Consulting Associates Limited | Health & social care | 2014 |
| J Cico Limited | Transport & logistics | 2012 |