| Intake Construction Solutions Ltd | Construction | 2011 |
| Intaprint Ltd | Administrative & support | 2009 |
| Integrated Energy Building Services Limited | Construction | 2014 |
| Integrated Interest Ltd | Information & communication | 2016 |
| Integratexpro Ltd | Information & communication | 2026 |
| Integrity Home Improvements Limited | Construction | 2025 |
| Intelligent Holdings Ltd | Financial services | 2008 |
| Intelligent Vending Ltd | Wholesale & retail | 2005 |
| Intelligently Automated Ltd | Extraterritorial | 2018 |
| Intelligently Automated Systems Ltd | Extraterritorial | 2018 |
| Intemax Ltd | Extraterritorial | 2025 |
| Intensive Property Solutions Ltd | Real estate | 2019 |
| Interactive Weather Limited | Information & communication | 2024 |
| Interhatch Limited | Extraterritorial | 2020 |
| International Learning Limited | Administrative & support | 1997 |
| International NDT Solutions Limited | Professional & scientific | 2022 |
| International Precision Engineering Limited | Manufacturing | 2022 |
| International Solutions Direct Ltd | Professional & scientific | 2021 |
| International Sustainable Development Research Society Limited | Education | 2026 |
| Interpreting BSL Services Ltd | Administrative & support | 2019 |
| Interpunkt Ltd | Manufacturing | 2021 |
| Intertec Ltd | Professional & scientific | 2015 |
| Inthenorth Ltd | Information & communication | 2022 |
| Intoo (UK) Limited | Administrative & support | 2016 |
| Intraderm (UK) Limited | Other services | 2005 |
| Intras Limited | Other services | 1984 |
| Intrax Limited | Financial services | 2015 |
| Intuitive Electrical Ltd | Construction | 2021 |
| Inverse Square Audio Ltd | Information & communication | 2017 |
| Invest Flip Ltd | Financial services | 2024 |
| Invest Home Property Ltd | Real estate | 2025 |
| Invest in Skills People Limited | Education | 2008 |
| Investment Analytics Limited | Professional & scientific | 2023 |
| Invictus Scaffolding & Safety Ltd | Construction | 2026 |
| Invision Secondary Glazing Limited | Construction | 2021 |
| IO Commercial Property Limited | Real estate | 2024 |
| IO Connect Ltd | Education | 2025 |
| IP Property Solutions Ltd | Real estate | 2019 |
| Ipera Services Limited | Administrative & support | 2022 |
| Ipsum Asset Management Limited | Extraterritorial | 2017 |
| Ipsum Capital (GB) Limited | Administrative & support | 2017 |
| Ipsum Capital (UK) Limited | Administrative & support | 2017 |
| Ipsum Capital Holdings Limited | Financial services | 2022 |
| Ipsum Capital Limited | Administrative & support | 2016 |
| Ipsum Commercial Limited | Extraterritorial | 2016 |
| Ipsum Finance Limited | Extraterritorial | 2016 |
| Ipsum Holdings Limited | Financial services | 2016 |
| IR Estates Limited | Extraterritorial | 2013 |
| Iridium Property Services Ltd | Real estate | 2011 |
| IRM (UK) Ltd | Wholesale & retail | 2020 |
| IRM Contractors Limited | Construction | 2013 |
| Iron Foundry Gym & Fitness Limited | Arts & recreation | 2021 |
| Isaab Consultancy Limited | Information & communication | 2017 |
| Isafe - Health Safety & Quality Services Limited | Professional & scientific | 2016 |
| Isaiahzion Ltd | Wholesale & retail | 2026 |
| Isara Capital Limited | Financial services | 2022 |
| Island Bay Design Ltd | Information & communication | 2021 |
| IT3000 Limited | Information & communication | 2006 |
| Itab Safety Consultancy Limited | Professional & scientific | 2023 |
| Itrack Ltd. | Wholesale & retail | 2018 |
| Ivolve 1 Head Office Limited | Professional & scientific | 2022 |
| Ivolve 2 Head Office Limited | Professional & scientific | 2022 |
| Ivolve Care Holdings Limited | Real estate | 2018 |
| Ivolve Care Management (Gresham Cavendish) Limited | Professional & scientific | 2020 |
| Ivolve Care Management (Heathcotes) Limited | Professional & scientific | 2020 |
| Ivolve Care Management (New Directions) Limited | Professional & scientific | 2020 |
| Ivolve Care Management (TLC) Limited | Professional & scientific | 2020 |
| Ivolve Fieldbay Bidco Ltd | Financial services | 2019 |
| Ivolve Group Limited | Health & social care | 2020 |
| Ivolve NO2 Limited | Health & social care | 2021 |
| Ivolve NO3 Limited | Health & social care | 2021 |
| Ivolve TY Heulog Ltd | Health & social care | 2023 |
| IVY Blue Homes Ltd | Real estate | 2020 |
| Iwan James Joinery Ltd | Construction | 2026 |
| Ixiom Limited | Information & communication | 2017 |
| J & H Fire Systems Limited | Construction | 2017 |
| J & J Contract Flooring Limited | Construction | 2011 |
| J & J Hamilton Plant Transport & Crane Hire Ltd | Transport & logistics | 2021 |
| J & M Lister Plumbing & Heating Limited | Construction | 2014 |
| J & P Contracts (Derby) Limited | Construction | 2003 |
| J & R Self Storage Chesterfield Ltd | Other services | 2016 |
| J & S Property Empire Ltd | Real estate | 2018 |
| J . Clark Haulage Ltd | Professional & scientific | 2025 |
| J a Builders (NED) Limited | Construction | 2016 |
| J a Ogden Plumbing and Heating Limited | Construction | 2012 |
| J a Scaffolding Solutions Limited | Construction | 2025 |
| J Ashton Limited | Construction | 2018 |
| J B King & SON Ltd | Construction | 2004 |
| J B Littlewood (Chesterfield) Limited | Wholesale & retail | 2011 |
| J Bamford Roofing Ltd | Construction | 2026 |
| J Bingham Homes Limited | Real estate | 2024 |
| J C Electrical Developments Limited | Construction | 2005 |
| J C Wilson Hairdressing Limited | Other services | 2015 |
| J Coupe Decorating Ltd | Construction | 2024 |
| J D Gibson Plumbing & Heating Ltd | Construction | 2017 |
| J E Wood & Sons Ltd | Real estate | 2025 |
| J F Heating Services Limited | Construction | 2017 |
| J G Cartwright Limited | Construction | 2017 |
| J G Electrical Services Ltd | Construction | 2007 |
| J G G Electrical and Maintenance Ltd | Other services | 2020 |