| Iron Oath Ltd | Wholesale & retail | 2026 |
| Iron World Fabrication Ltd | Manufacturing | 2019 |
| Ironbark Investment Partners (UK) Ltd | Financial services | 2022 |
| Ironbase Capital Ltd | Real estate | 2026 |
| Ironbase Properties Ltd | Real estate | 2026 |
| Ironbridge Revenue Ltd | Professional & scientific | 2026 |
| Ironclad Security Solutions Ltd | Administrative & support | 2026 |
| Ironclean Services Limited | Administrative & support | 2026 |
| Irongate Securities Ltd | Wholesale & retail | 2025 |
| Irongates Property Limited | Real estate | 2025 |
| Ironhand Security Services Ltd | Administrative & support | 2026 |
| Ironpaw Pro Ltd | Manufacturing | 2026 |
| Ironphenatix Ltd | Wholesale & retail | 2024 |
| Ironsmart Limited | Financial services | 2025 |
| Irontec Safety Limited | Wholesale & retail | 2025 |
| Ironwheels Transport Ltd | Wholesale & retail | 2025 |
| Ironwood Capital Limited | Real estate | 2023 |
| Ironwood Flooring Services Ltd | Construction | 2012 |
| Ironwood Homes Ltd | Construction | 2023 |
| Ironwood Installation Services Ltd. | Construction | 2015 |
| Ironwood Investments Ltd | Real estate | 2021 |
| Ironwood Property Management Ltd | Real estate | 2016 |
| Ironwood Rental Ltd | Real estate | 2024 |
| Iroot Limited | Information & communication | 2019 |
| Irreplaceable Taste Ltd | Hospitality | 2018 |
| Irritable Monkey Productions Ltd | Information & communication | 2022 |
| Irro Commercial East & Travel Limited | Other services | 2016 |
| Irsam Clothing 19 Limited | Wholesale & retail | 2026 |
| Irsha Energies Ltd | Construction | 2025 |
| Irshad Ullah Ltd | Wholesale & retail | 2025 |
| Irshtak Properties Limited | Real estate | 2002 |
| Irsq Ltd | Real estate | 2023 |
| Irtiqqa Business Group Ltd | Wholesale & retail | 2021 |
| Irum Saleem Interpreting Ltd | Professional & scientific | 2026 |
| Irums Consulting Limited | Information & communication | 2021 |
| Irums Property Management Limited | Real estate | 2022 |
| Irwell Asset Solutions Limited | Financial services | 2025 |
| Irwell Chambers Estates Limited | Construction | 2012 |
| Irwell Chambers Management Company Limited | Real estate | 2008 |
| IS Guarding Limited | Administrative & support | 2025 |
| IS Logistics London Limited | Transport & logistics | 2024 |
| IS Mechanics Ltd | Wholesale & retail | 2024 |
| IS Portfolio Limited | Real estate | 2021 |
| IS Property Holdings Limited | Real estate | 2024 |
| IS Telecom Ltd | Information & communication | 2019 |
| IS2 Ltd | Information & communication | 1996 |
| ISA LGV Express Ltd | Transport & logistics | 2019 |
| ISA Furniture Ltd | Wholesale & retail | 2023 |
| ISA Halal Ltd | Wholesale & retail | 2014 |
| ISA Invest Ltd | Real estate | 2020 |
| ISA LGV Transport Ltd | Transport & logistics | 2025 |
| ISA Plumbing and Carpenter Ltd | Construction | 2025 |
| ISA Property Holdings Ltd | Financial services | 2025 |
| ISA Property Investment Ltd | Real estate | 2024 |
| ISA Security Ltd | Extraterritorial | 2018 |
| ISA Support Services Limited | Administrative & support | 2011 |
| ISA Supported Living Ltd | Real estate | 2025 |
| Isa-Uk Ltd | Education | 2014 |
| ISA1 Ltd | Wholesale & retail | 2025 |
| Isaac Court Limited | Real estate | 2012 |
| Isaac Tyres Birmingham Limited | Wholesale & retail | 2022 |
| Isaacos Limited | Wholesale & retail | 2019 |
| Isaacs Growth Ltd | Professional & scientific | 2026 |
| Isaacs Law Limited | Professional & scientific | 2020 |
| Isaacs Legal Services Limited | Professional & scientific | 2020 |
| Isaacs Property Holdings Ltd | Financial services | 2025 |
| Isabella City Gate Ltd | Information & communication | 2026 |
| Isabella Rowles Limited | Real estate | 2019 |
| Isak Daniel Ltd | Construction | 2026 |
| Isak Properties Limited | Real estate | 2022 |
| Isamax Midlands Ltd | Administrative & support | 2024 |
| Isamrailengineering Ltd | Construction | 2023 |
| Isatech Ltd | Wholesale & retail | 2022 |
| Isba Holdings Ltd | Real estate | 2022 |
| ISC Enterprise Ltd | Real estate | 2025 |
| Iscope Eyewear Limited | Wholesale & retail | 2025 |
| Isda Properties Ltd | Other services | 2022 |
| Isdm Investment Ltd | Real estate | 2022 |
| Isearch International Ltd | Administrative & support | 2025 |
| Isecurity Force Ltd | Administrative & support | 2025 |
| Isfaf Tutors Ltd | Education | 2025 |
| Isfahan Real Estate Limited | Real estate | 2025 |
| ISG Pharmaceuticals Ltd | Health & social care | 2025 |
| ISH TM Ltd | Construction | 2022 |
| Isha & Maya Ltd | Extraterritorial | 2016 |
| Isha Academy Ltd | Education | 2021 |
| Isha Events Limited | Administrative & support | 2025 |
| Ishaq Financial Consulting Ltd | Administrative & support | 2014 |
| Ishaque Spinal Services Limited | Health & social care | 2010 |
| Ishastonproperties Limited | Real estate | 2026 |
| Ishatech Limited | Information & communication | 2024 |
| Ishaw Solutions Ltd | Transport & logistics | 2025 |
| Ishfaq Ahmad Store Ltd | Wholesale & retail | 2025 |
| Ishi AI Platforms Ltd | Information & communication | 2026 |
| Ishi AI Research Ltd | Information & communication | 2026 |
| Ishida Europe Ltd. | Manufacturing | 1984 |
| Ishine Express D Ltd | Administrative & support | 2023 |
| Ishine Express GM Ltd | Administrative & support | 2022 |
| Ishk Ltd | Wholesale & retail | 2023 |
| Ishmael Property Group Ltd | Real estate | 2025 |