| Iqra Finance Ltd. | Financial services | 2025 |
| Iqra Promotions Ltd | Information & communication | 2016 |
| Iqra Retail Ltd | Wholesale & retail | 2022 |
| IQS Europe Ltd | Information & communication | 2011 |
| IRC (Windows & Doors) Ltd | Manufacturing | 2016 |
| Ire's Pots Limited | Hospitality | 2025 |
| Irepair Stop (Sales) Ltd | Wholesale & retail | 2020 |
| Irepair Stop Limited | Other services | 2017 |
| Iricris Ltd | Construction | 2021 |
| Iris Secure Ltd | Financial services | 2025 |
| Iris Shop Ltd | Wholesale & retail | 2026 |
| Iron AGE Archery Ltd | Arts & recreation | 2021 |
| Iron Oak Properties Limited | Real estate | 2024 |
| Ironcore Demolition Ltd | Construction | 2026 |
| Ironstone Investments Limited | Real estate | 2020 |
| Ironworks Property Investments Limited | Real estate | 2017 |
| Irs.Direct Ltd | Wholesale & retail | 2025 |
| Irshpick Ltd | Wholesale & retail | 2021 |
| Irtaza Farooq Ltd | Arts & recreation | 2021 |
| Irwin Mitchell Charities Foundation | Administrative & support | 2012 |
| Irwin Mitchell LLP | | 2009 |
| Irwin Mitchell Nominees Limited | Extraterritorial | 2008 |
| Irwin Mitchell Nominees Number Two Limited | Extraterritorial | 2008 |
| Irwin Mitchell Secretaries Limited | Professional & scientific | 1993 |
| Irwin Mitchell Trust Corporation Limited | Administrative & support | 2009 |
| Irwin Mitchell Trustees Corporation Limited | Extraterritorial | 2008 |
| Irwin Mitchell Trustees Limited | Financial services | 2010 |
| IS Logistics Ltd | Transport & logistics | 2026 |
| Isaac Nash & Sons Limited | Extraterritorial | 1997 |
| Isabella Roux Limited | Manufacturing | 2016 |
| Isam Holdings Limited | Real estate | 2024 |
| Isanow & Co Ltd | Financial services | 2015 |
| Isecondthat Ltd | Wholesale & retail | 2020 |
| Isedio Limited | Manufacturing | 2009 |
| Iseeu Ltd | Health & social care | 2026 |
| Ishaah Enterprise Ltd | Wholesale & retail | 2026 |
| Ishy Properties Limited | Real estate | 2023 |
| Isidore IT Ltd | Professional & scientific | 2010 |
| Isin Nippur Limited | Health & social care | 2009 |
| ISIVOR12 Ltd | Other services | 2018 |
| ISJ Specialist Assessments Limited | Health & social care | 2016 |
| Iskan Holdings Limited | Real estate | 2019 |
| Isla Hoque Ltd | Hospitality | 2026 |
| Isla Scores Limited | Professional & scientific | 2011 |
| Islamabad Curry House Ltd | Hospitality | 2021 |
| Islamabad Takeaway Ltd | Hospitality | 2025 |
| Islamic Radiance Ltd | Wholesale & retail | 2025 |
| Islamic Will Writers Limited | Professional & scientific | 2024 |
| Island Chef 2024 Ltd | Hospitality | 2025 |
| Island Life (South Yorkshire) Limited | Construction | 2016 |
| Island Site (General Partner) Limited | Real estate | 2018 |
| Island Site (Nominee) Limited | Real estate | 2018 |
| Islo Ltd | Professional & scientific | 2019 |
| Isnex Technologies Ltd | Wholesale & retail | 2024 |
| Isni Ltd | Health & social care | 2024 |
| Isobel Hulse Limited | Wholesale & retail | 2024 |
| Isopharm Limited | Manufacturing | 1999 |
| Isosceles Investments Limited | Real estate | 2019 |
| Isostatic Forging International Europe Limited | Other services | 2002 |
| Isostatix Limited | Manufacturing | 2017 |
| Isostock Limited | Information & communication | 1998 |
| Isra Trade Dynamics Ltd | Wholesale & retail | 2025 |
| Issa Sushi UK Ltd | Hospitality | 2015 |
| Issan Beauty Spa Limited | Other services | 2015 |
| Istvan Lakatos Ltd | Construction | 2019 |
| Isvr Consulting Limited | Extraterritorial | 2023 |
| Isys Care Limited | Health & social care | 2013 |
| IT - Community School & Subject Support | Education | 2002 |
| IT Centre Limited | Information & communication | 2018 |
| IT Experts Global Ltd | Information & communication | 2018 |
| IT Ferret Limited | Information & communication | 2004 |
| IT Mistry Limited | Information & communication | 2013 |
| IT Perfection Limited | Administrative & support | 2016 |
| IT Wireless (UK) Limited | Information & communication | 2011 |
| It's a Religion Limited | Professional & scientific | 2022 |
| It's Interventional Limited | Wholesale & retail | 1987 |
| It's Interventional Regulatory Limited | Administrative & support | 2020 |
| It's My Life Ltd | Health & social care | 2011 |
| It's Never Simple Limited | Arts & recreation | 2022 |
| It's Unknown Limited | Administrative & support | 2015 |
| Italian Delicatese Ltd | Construction | 2020 |
| Itch Innovation UK Limited | Manufacturing | 2020 |
| Itch Manufacturing Ltd. | Manufacturing | 2020 |
| Itech Diagnostics Limited | Information & communication | 2018 |
| Iteei Ltd | Construction | 2026 |
| Itendx Ltd | Wholesale & retail | 2022 |
| ITI Digital Solutions Limited | Information & communication | 1997 |
| ITI Engineering Group Limited | Financial services | 2018 |
| ITI Engineering Holdings Limited | Financial services | 2018 |
| ITI Network Services Limited | Information & communication | 1995 |
| ITI Operations Limited | Information & communication | 2002 |
| Iticy Ltd | Professional & scientific | 2020 |
| Itinerant IT Ltd | Information & communication | 2018 |
| ITM Power (Research) Limited | Manufacturing | 2000 |
| ITM Power (Shelfco) Limited | Manufacturing | 2013 |
| ITM Power PLC | Manufacturing | 2004 |
| ITM Power UK Limited | Manufacturing | 2007 |
| Itmspuk Limited | Information & communication | 2025 |
| ITN Corporation Limited | Arts & recreation | 2009 |
| Itqua Limited | Information & communication | 2019 |