| I.Q.I.P. Limited | Real estate | 2017 |
| I.R. Clapham Plumbers (1984) Ltd | Construction | 2025 |
| I.Sawyu.Uk Ltd | Manufacturing | 2026 |
| I.Siddique Leeds Ltd | Administrative & support | 2024 |
| I.Siddique Ltd | Administrative & support | 2018 |
| I.X.P. Limited | Administrative & support | 1970 |
| I.Z Accountancy Ltd | Professional & scientific | 2024 |
| I.Z Accountants Ltd | Professional & scientific | 2017 |
| I.Z Investments Ltd | Construction | 2022 |
| I23 Capital Limited | Manufacturing | 2023 |
| I2I Technologies (UK) Limited | Information & communication | 2018 |
| I3M Property Holdings Ltd | Real estate | 2022 |
| IA Contractor Leeds Limited | Professional & scientific | 2015 |
| IA Marketing Services Ltd | Wholesale & retail | 2025 |
| IA Real Estate Group Ltd | Real estate | 2023 |
| IA Takeaway Ltd | Hospitality | 2023 |
| Iaaz Properties Ltd | Real estate | 2026 |
| Iacob B Delivery Ltd | Transport & logistics | 2024 |
| IAG 1919 Group Ltd | Financial services | 2023 |
| IAG Growth Ltd | Other services | 2023 |
| IAG1919 Ltd | Professional & scientific | 2021 |
| Iain Hall Holdings Limited | Financial services | 2017 |
| Iain Hall Sealant Supplies Limited | Construction | 2012 |
| Iain Hall Sealants Limited | Construction | 1998 |
| Iain Hall Sealants Trustees Limited | Other services | 2025 |
| Iain Starks Limited | Information & communication | 2008 |
| Iaju Ltd | Wholesale & retail | 2023 |
| IAM Facilities Management Limited | Other services | 2013 |
| Iamandi M Delivery Ltd | Transport & logistics | 2023 |
| Iamethod Limited | Information & communication | 2026 |
| Iamgaz Ltd | Professional & scientific | 2025 |
| Iamshanov Limited | Professional & scientific | 2018 |
| IAN Bell Limited | Administrative & support | 2011 |
| IAN Bowyer Limited | Information & communication | 2014 |
| IAN Brame Limited | Other services | 1999 |
| IAN Brannan Limited | Information & communication | 2013 |
| IAN Davies Installations Ltd | Construction | 2024 |
| IAN Duggleby Solutions Limited | Professional & scientific | 2025 |
| IAN Dunford (Properties) Limited | Extraterritorial | 1995 |
| IAN Dunford Limited | Wholesale & retail | 1975 |
| IAN Feber Ltd | Real estate | 2014 |
| IAN Firth Holdings Limited | Professional & scientific | 2008 |
| IAN Richards & Co (Leeds) Limited | Professional & scientific | 2009 |
| IAN Simmons Ophthalmics Limited | Health & social care | 2010 |
| IAN Smith Holdings Limited | Administrative & support | 2018 |
| IAN Stokes Education Ltd | Education | 2016 |
| IAN Underwood Consulting Limited | Professional & scientific | 2025 |
| IAN Vickers Marketing Ltd | Professional & scientific | 2010 |
| Ian's Helping Hands Ltd | Other services | 2019 |
| Ian-Den Trans Ltd | Transport & logistics | 2019 |
| Ianbrant Limited | Health & social care | 2023 |
| Iancu IVG Ltd | Transport & logistics | 2023 |
| Iancwilson Ltd | Health & social care | 2023 |
| Iands Property Investments Ltd | Real estate | 2024 |
| Iane Limited | Energy | 2003 |
| Ians Auto Repairs Ltd | Wholesale & retail | 2026 |
| IAR Property Holdings Limited | Real estate | 2025 |
| Iarep Ltd | Education | 2007 |
| IAS Developments Ltd | Real estate | 2014 |
| Iasm Consulting Limited | Information & communication | 2013 |
| IB Autos Limited | Wholesale & retail | 2009 |
| IB Direct Ltd | Wholesale & retail | 2025 |
| IB Holding Leeds Ltd | Financial services | 2020 |
| IB Sports Ltd | Arts & recreation | 2026 |
| IBA Consulting Ltd | Information & communication | 2018 |
| Ibase Media Services Ltd | Information & communication | 2005 |
| Ibbetas Maintenance & Developments Ltd | Construction | 2024 |
| Ibbetas Property Group Ltd | Construction | 2024 |
| Ibbotson Brady Solicitors Limited | Professional & scientific | 2013 |
| Ibbotson Roofing Ltd | Construction | 2026 |
| Ibbys Car Recovery Ltd | Wholesale & retail | 2024 |
| Ibee's Social Care Limited | Health & social care | 2016 |
| Ibex Healthcare Ltd | Health & social care | 2023 |
| Ibiab Property and Investments Ltd | Real estate | 2023 |
| Ibiab Systems Ltd | Information & communication | 2020 |
| Ibidlots Ltd | Wholesale & retail | 2026 |
| Ibikhan Limited | Wholesale & retail | 2025 |
| IBN Traders Worldwide Limited | Wholesale & retail | 2020 |
| Ibox Healthcare Limited | Information & communication | 2012 |
| Ibrahim Halal Meat Ltd | Wholesale & retail | 2012 |
| Ibrahim Peadiatric Ltd | Health & social care | 2010 |
| Ibusinesstransformation Ltd | Information & communication | 2019 |
| IC Accounting Limited | Professional & scientific | 2023 |
| IC Blue Electronics Limited | Wholesale & retail | 2006 |
| IC Blue Limited | Wholesale & retail | 2002 |
| IC Blue Technology Limited | Professional & scientific | 2012 |
| IC Italian Ltd | Hospitality | 2023 |
| Ican London Ltd | Wholesale & retail | 2023 |
| Icando UK Limited | Financial services | 2013 |
| Icapital Ltd | Financial services | 2021 |
| Icare Accountancy Limited | Professional & scientific | 2025 |
| Icare World Ltd | Health & social care | 2014 |
| Icarus DW Limited | Manufacturing | 2025 |
| Icarus International Energy Group Ltd | Professional & scientific | 2023 |
| ICB Holdings Limited | Financial services | 2001 |
| ICB Securities 1 Limited | Administrative & support | 2006 |
| ICB Securities 2 Unlimited | Administrative & support | 1998 |
| ICD Property Group Ltd | Real estate | 2026 |
| Ice Cold Events Ltd | Manufacturing | 2023 |
| Ice Cream TUK Ltd | Hospitality | 2023 |