| IL Maranese Limited | Hospitality | 2022 |
| IL Ponte Limited | Hospitality | 2001 |
| IL Vicoletto Limited | Hospitality | 2024 |
| ILA Holdings Ltd | Administrative & support | 2025 |
| ILD Builders Limited | Construction | 2013 |
| Ilda Europe Limited | Professional & scientific | 2012 |
| Ildiko Cleaning Service Ltd | Administrative & support | 2016 |
| Ilhouseofbeauty Ltd | Other services | 2024 |
| Ilian Hristov Ltd | Construction | 2016 |
| Ilianna Apartments Ltd | Real estate | 2022 |
| ILK Builders Ltd | Construction | 2022 |
| Illyria Limited | Households | 2001 |
| Iluxe Ltd | Transport & logistics | 2020 |
| Ilys Organic Ltd | Wholesale & retail | 2017 |
| IM Ambassador Ltd | Education | 2024 |
| IM Baig Services Ltd | Professional & scientific | 2024 |
| IM Just Dicee Ltd | Administrative & support | 2021 |
| IMA Creative Limited | Professional & scientific | 2019 |
| Imaalia Limited | Real estate | 2021 |
| Image of Dorking Limited | Manufacturing | 2012 |
| Imakh Limited | Real estate | 2013 |
| Iman Cleaning Services Limited | Administrative & support | 2025 |
| IMB BIA Services Limited | Health & social care | 2026 |
| Imco Offices Limited | Real estate | 2019 |
| IMG Builders (Surrey) Limited | Construction | 2021 |
| IMH Waseems Limited | Manufacturing | 2025 |
| Imid Ltd | Wholesale & retail | 2023 |
| Imimerchants Ltd | Wholesale & retail | 2025 |
| Immaculate Business Solutions Ltd | Transport & logistics | 2022 |
| Immaculate Travel Ltd | Transport & logistics | 2019 |
| Immortal Jewellery Limited | Manufacturing | 2021 |
| Immourse Ltd | Information & communication | 2019 |
| Impackta Limited | Information & communication | 2002 |
| Impact Boxing Club C.I.C. | Education | 2021 |
| Impact Investment Partners LLP | | 2011 |
| IMPACTMEDIA624 Limited | Information & communication | 2025 |
| Impel London Limited | Information & communication | 2020 |
| Imperial B&R Ltd | Hospitality | 2019 |
| Imperial City Development Limited | Construction | 2014 |
| Imperial Gold Holdings Ltd | Other services | 2024 |
| Imperial House Banqueting Ltd | Hospitality | 2023 |
| Imperial Oaks Ltd | Education | 2024 |
| Imperial Security Services Limited | Administrative & support | 2017 |
| Imperial Square Ltd | Real estate | 2017 |
| Imperial Tutoring Limited | Extraterritorial | 2023 |
| Imperial Visas DOT COM Ltd | Professional & scientific | 2011 |
| Imperial Wooden Doors Ltd | Construction | 2019 |
| Imperium Rentals Ltd | Administrative & support | 2025 |
| Implement (UK) Limited | Construction | 2009 |
| Impress Kitchens Ltd | Wholesale & retail | 2009 |
| Improvecx Limited | Information & communication | 2015 |
| Impulse Management and Accounting Limited | Administrative & support | 2008 |
| Imraja Consult Ltd | Information & communication | 2018 |
| Imraja Properties Limited | Real estate | 2021 |
| IMZ Ventures Ltd | Information & communication | 2025 |
| IN 2 Deep Ltd | Information & communication | 2025 |
| IN Control Ltd | Professional & scientific | 2024 |
| IN Wisdom Ltd | Construction | 2019 |
| In&G Services Ltd | Construction | 2023 |
| In-Tel Limited | Information & communication | 2024 |
| In-Terr-Connect Ltd | Information & communication | 2023 |
| Inalytics Holdings Limited | Financial services | 2014 |
| Inalytics Ltd | Information & communication | 1998 |
| Inaventure UK Limited | Information & communication | 2014 |
| Inbro Citygate Insurance Brokers Ltd. | Financial services | 1984 |
| Ince Staffing & Recruitment Ltd | Administrative & support | 2026 |
| Ince&Son Ltd | Construction | 2025 |
| Increase the Value Ltd | Administrative & support | 2017 |
| Incredibles Removals Ltd | Transport & logistics | 2025 |
| Independent Care Partners Ltd | Health & social care | 2025 |
| Independent Research Limited | Professional & scientific | 2000 |
| Index Group UK & EU Ltd | Professional & scientific | 2025 |
| Indexme Limited | Other services | 2018 |
| India Development Group (U.K.) Limited | Professional & scientific | 1980 |
| Indian Mermaid Hair Xtension Ltd | Professional & scientific | 2013 |
| Indiano Westino Couture London Limited | Wholesale & retail | 2025 |
| Indie House PR Limited | Professional & scientific | 2020 |
| Indigo Fostering Ltd | Health & social care | 2023 |
| Indigo Instincts Management Services Limited | Real estate | 2010 |
| Indigo Technologies Ltd | Information & communication | 2016 |
| Indigroid Interiors Limited | Real estate | 1972 |
| Indira's Kitchen Ltd | Hospitality | 2026 |
| Inditherm (Medical) Limited | Extraterritorial | 1998 |
| Indra One Limited | Wholesale & retail | 2025 |
| Indus PVT Ltd | Hospitality | 2019 |
| Industrial Outlet Limited | Wholesale & retail | 2013 |
| Inemisart Ltd | Professional & scientific | 2016 |
| Infa (UK) Ltd | Wholesale & retail | 2011 |
| Infiiniity Ltd | Wholesale & retail | 2019 |
| Infina Creations Ltd | Wholesale & retail | 2025 |
| Infinankh Holdings Limited | Financial services | 2025 |
| Infinite Advisory Services Ltd | Professional & scientific | 2024 |
| Infinite Community Consultant Limited | Professional & scientific | 2025 |
| Infinite Grace Consultancy Ltd | Professional & scientific | 2022 |
| Infinite Phrases Limited | Wholesale & retail | 2024 |
| Infiniti Property Investments Ltd | Construction | 2025 |
| Infiniti Property Limited | Information & communication | 2020 |
| Infiniti-Net Ltd | Other services | 2016 |
| Infinitude Outcomes Ltd | Transport & logistics | 2017 |
| Infinity Coffee Croydon Ltd | Hospitality | 2026 |