| Irada Supplies Company Ltd | Manufacturing | 2025 |
| Irat Parcel Delivery Limited | Transport & logistics | 2016 |
| Irba Ltd | Wholesale & retail | 2025 |
| Ireland Properties Ltd | Real estate | 2020 |
| Iremia Global Ltd | Information & communication | 2026 |
| Irepresent CIC | Information & communication | 2025 |
| Irfanlocums Ltd | Health & social care | 2019 |
| IRG Management Ltd | Professional & scientific | 2012 |
| IRH Consultancy Limited | Professional & scientific | 2007 |
| Irha Jewellers Ltd | Wholesale & retail | 2025 |
| Irifelix Limited | Manufacturing | 2016 |
| Iris Commercial Consulting Ltd | Professional & scientific | 2025 |
| Iris Finance Ltd | Other services | 2016 |
| Iris Productions Ltd | Information & communication | 2019 |
| Iris Signs Ltd | Professional & scientific | 2018 |
| Irom Service Ltd | Transport & logistics | 2016 |
| Iron Auto Ltd | Wholesale & retail | 2025 |
| Iron Forge Gym Ltd | Arts & recreation | 2025 |
| Iron Horse Garage Ltd | Wholesale & retail | 2025 |
| Iron Sight Analysis Limited | Information & communication | 2015 |
| Iron Swan Limited | Administrative & support | 2018 |
| Ironbridge Prime Ltd | Transport & logistics | 2014 |
| Ironcrest Builders Ltd | Construction | 2025 |
| Ironstone Development (East Midlands) Limited | Construction | 2013 |
| IRP Consulting Limited | Other services | 2010 |
| IRRI-G8 Limited | Water & waste | 2013 |
| Irrifence Ltd | Water & waste | 2007 |
| Irro Property Management Ltd | Hospitality | 2022 |
| Irro Property Solutions Ltd | Real estate | 2019 |
| Irsip Construction Ltd | Manufacturing | 2024 |
| Irsmarketing Limited | Administrative & support | 2005 |
| Irst Ltd | Hospitality | 2019 |
| IRST2 Ltd | Hospitality | 2019 |
| Irum Ltd | Health & social care | 2008 |
| IS Energy Consulting Limited | Households | 2024 |
| IS Eyecare Ltd | Health & social care | 2023 |
| IS86 Trading Limited | Wholesale & retail | 2024 |
| Isa-Computec Limited | Real estate | 2004 |
| Isaac Care Solutions Ltd | Professional & scientific | 2018 |
| Isaac Chili Ltd | Transport & logistics | 2023 |
| Isaac's Treasures Ltd | Wholesale & retail | 2020 |
| Isaacstephen Ltd | Wholesale & retail | 2025 |
| Isabel Lane Kibworth Limited | Households | 2006 |
| Isabella's Cafe Limited | Hospitality | 2020 |
| Isabelle Stratford Ltd | Real estate | 2019 |
| Isak Leic Ltd | Manufacturing | 2020 |
| Isaura Properties Limited | Professional & scientific | 2006 |
| Ischool Online Global Ltd | Education | 2024 |
| Ischool Online Ltd | Education | 2020 |
| ISE Pharma Ltd | Health & social care | 2024 |
| Isella & Margjoni Ltd | Real estate | 2026 |
| Iseran Ltd | Real estate | 2026 |
| ISF Coatings Limited | Manufacturing | 1982 |
| ISF Group Holdings Limited | Financial services | 2026 |
| ISG Contracts Limited | Professional & scientific | 2011 |
| ISG Homes Limited | Real estate | 2006 |
| Isha Patisserie Limited | Wholesale & retail | 2020 |
| Ishan-Sattva Development Services Limited | Health & social care | 2025 |
| Isher Automotors Limited | Manufacturing | 2023 |
| Isher Financial Ltd | Financial services | 2019 |
| Ishgram Ltd | Wholesale & retail | 2018 |
| Ishiv 1 Ltd | Wholesale & retail | 2015 |
| Ishiv Group Ltd | Real estate | 2016 |
| Ishna Limited | Wholesale & retail | 2014 |
| Ishwar Solicitors Ltd | Professional & scientific | 2026 |
| Ishween Ltd | Wholesale & retail | 2023 |
| Ishwood Properties Ltd | Real estate | 2025 |
| Isinstore Ltd | Professional & scientific | 2020 |
| ISJ Independent Financial Planning Limited | Financial services | 2016 |
| ISJ Limited | Administrative & support | 2021 |
| Iskan Group Ltd | Construction | 2020 |
| Iskan Ltd | Construction | 2022 |
| ISL Leicester Ltd | Construction | 2022 |
| Isla Fennell Limited | Other services | 2017 |
| Islah Group Ltd | Hospitality | 2025 |
| Islamic Finance Training & Advisory Limited | Professional & scientific | 2020 |
| Islamic Ratings Ltd | Professional & scientific | 2025 |
| Island Lighting Limited | Arts & recreation | 1996 |
| Island Pride Foods Ltd | Wholesale & retail | 2021 |
| Isle of Social Ltd | Professional & scientific | 2022 |
| Ismail Builders Ltd | Construction | 2020 |
| Ismail K Catering Ltd | Hospitality | 2025 |
| Ismail Services Ltd | Health & social care | 2012 |
| Ismail Ventures Limited | Financial services | 2025 |
| Ismart Electrical Solutions Ltd | Construction | 2019 |
| Ismart Energy Solution Ltd | Other services | 2024 |
| ISN Distributors Ltd | Wholesale & retail | 2013 |
| Isnacks Ltd | Extraterritorial | 2018 |
| ISO Security Systems Ltd | Manufacturing | 2018 |
| ISO2ISO Ltd | Information & communication | 2023 |
| Isogon Systems Limited | Professional & scientific | 2015 |
| Isometric Product Design Limited | Professional & scientific | 2011 |
| Ispoke Languages Ltd | Administrative & support | 2016 |
| Ispy Solutions Limited | Information & communication | 2006 |
| Issa Logistics Ltd | Transport & logistics | 2025 |
| Isse Food Court Ltd | Hospitality | 2022 |
| Isshoni Limited | Hospitality | 2018 |
| IST Holdings Limited | Information & communication | 2017 |
| IST Power Holdings Limited | Financial services | 2020 |
| Istana Limited | Extraterritorial | 2012 |