| Ihome Limited | Other services | 2013 |
| Iilm Consultants Ltd | Professional & scientific | 2018 |
| IIM Bangalore UK Alumni Limited | Other services | 2024 |
| Iimt Studies Ltd | Education | 2018 |
| IJ Heating & GAS Limited | Construction | 2019 |
| IJ Heating and Plumbing Ltd | Construction | 2023 |
| Ijar Limited | Financial services | 2024 |
| Ijaz Management Limited | Real estate | 2004 |
| IJX Ltd | Information & communication | 2015 |
| IK-2000 Ltd | Information & communication | 2023 |
| Ikaa Properties Limited | Real estate | 2020 |
| Ikabal Limited | Wholesale & retail | 2025 |
| IKB Eventworks Ltd | Administrative & support | 2024 |
| IKB Property Development Ltd | Real estate | 2024 |
| Ikigai Innovations Limited | Information & communication | 2023 |
| Ikigai Rising Limited | Information & communication | 2023 |
| Ikloud Ltd | Administrative & support | 2015 |
| IKR Investments Ltd | Real estate | 2026 |
| Ikram Group Limited | Financial services | 2017 |
| IL Buono Caffe Ltd | Hospitality | 2021 |
| Il-Uk Fresh Produce Limited | Wholesale & retail | 2011 |
| Ila.Life Limited | Health & social care | 2017 |
| Iland Marketing and Construction Ltd | Professional & scientific | 2025 |
| Ilanelle Limited | Administrative & support | 2025 |
| Ilas Plastering Ltd | Construction | 2018 |
| Ilas Plumbing Ltd | Construction | 2018 |
| Ilaser Limited | Other services | 2019 |
| Ilashcorner Ltd | Hospitality | 2023 |
| ILC Carpentry Limited | Manufacturing | 2022 |
| Ildy Limited | Wholesale & retail | 2025 |
| Ilham and Dayr Ltd | Administrative & support | 2024 |
| Ilisoi Construction Ltd | Construction | 2019 |
| Ilka Ltd | Manufacturing | 2025 |
| Illi Rugs Limited | Wholesale & retail | 2024 |
| Illicit Hair Salon Ltd | Other services | 2026 |
| Illika Medical Limited | Health & social care | 2023 |
| Illuma Research Limited | Professional & scientific | 2013 |
| Illumeducation Ltd | Education | 2012 |
| Illyrian Flowers Ltd | Wholesale & retail | 2023 |
| ILM Services Limited | Other services | 2015 |
| Ilmo Aqoon Ltd | Education | 2018 |
| Ilmoveai Ltd | Information & communication | 2026 |
| Ilocksmiths.London Ltd | Manufacturing | 2026 |
| ILT Building Solutions Ltd | Construction | 2026 |
| Ilton Property Developments Limited | Construction | 2025 |
| Iluminaire Ltd | Wholesale & retail | 2023 |
| Ilymedia Ltd | Administrative & support | 2017 |
| Ilynx Limited | Other services | 2011 |
| Imaan Consultants Ltd | Professional & scientific | 2014 |
| Imaar Construction Ltd | Construction | 2026 |
| Image Builders Limited | Construction | 2013 |
| Imagico Limited | Professional & scientific | 2025 |
| Imagimake Play Solutions Ltd | Manufacturing | 2024 |
| Imagimosaic Ltd | Wholesale & retail | 2024 |
| Imaginaery Limited | Information & communication | 2023 |
| Imagine a World Limited | Real estate | 2016 |
| Imagine Beyond Limited | Administrative & support | 2019 |
| Imagine Innovation Ltd | Other services | 2023 |
| Imaging Endpoints Limited | Health & social care | 2021 |
| Imagitax Ltd | Professional & scientific | 2014 |
| Imamia Pilgrims Ltd | Other services | 2019 |
| Imap Orbital Limited | Real estate | 2018 |
| Imap Properties Ltd | Construction | 2011 |
| Imara Prime Limited | Financial services | 2025 |
| Imaxigreen Limited | Information & communication | 2014 |
| IMB SLT Ltd | Health & social care | 2026 |
| IMC Drive Ltd | Transport & logistics | 2026 |
| IMC Properties Limited | Construction | 1999 |
| IMC Solutions Ltd | Construction | 2026 |
| Imco International Ltd | Extraterritorial | 2007 |
| IME Global Holdings Ltd | Real estate | 2012 |
| Imedicus Limited | Health & social care | 2015 |
| IMK Properties (2) Ltd | Real estate | 2018 |
| Immaculate & Co. Ltd | Administrative & support | 2024 |
| Immerse X Limited | Other services | 2023 |
| Immersionn Limited | Information & communication | 2018 |
| Immerso Media Technologies Limited | Information & communication | 2025 |
| Immiworks Limited | Information & communication | 2026 |
| Immunition Ltd | Wholesale & retail | 2018 |
| Imodal Europe Limited | Professional & scientific | 2008 |
| Impact Investing Limited | Information & communication | 2014 |
| Impact Outreach Network Limited | Health & social care | 2004 |
| Impakt Properties Limited | Real estate | 1996 |
| Impendium Solutions Ltd | Construction | 2021 |
| Imperial Bay Ltd | Construction | 2026 |
| Imperial Care Management Limited | Professional & scientific | 2026 |
| Imperial Chariot Motors Limited | Wholesale & retail | 2025 |
| Imperial Developments Limited | Real estate | 2001 |
| Imperial Diagnostic Imaging Limited | Health & social care | 2022 |
| Imperial Drive (Harrow) Management Limited | Households | 2000 |
| Imperial Drive Properties Ltd | Real estate | 2021 |
| Imperial Garden Service Limited | Administrative & support | 2021 |
| Imperial Health and Nutrition Limited | Health & social care | 2013 |
| Imperial Luxury Homes Limited | Real estate | 2025 |
| Imperial Securities Ltd | Real estate | 2023 |
| Imperial Spirits Limited | Wholesale & retail | 2026 |
| Imperial Threads Company Ltd | Manufacturing | 2024 |
| Imperio CNC Ltd | Manufacturing | 2026 |
| Imperio Components Ltd | Manufacturing | 2026 |
| Imperium Growth Ltd | Information & communication | 2024 |