| Ignite Events Ltd | Wholesale & retail | 2014 |
| Ignite Hockey Camp Ltd | Education | 2026 |
| Ignite Partners Ltd | Real estate | 2024 |
| IHP Design & Construction Ltd | Construction | 2021 |
| IIM Cars Limited | Transport & logistics | 2025 |
| Ijeme Properties Ltd | Real estate | 2024 |
| Ikene Services Ltd | Construction | 2024 |
| Ikky's Hair Studio Ltd | Other services | 2025 |
| Ikma Consultancy Limited | Information & communication | 2010 |
| IL Pellegrino Watford Ltd | Hospitality | 2024 |
| ILA Logistics Limited | Manufacturing | 2025 |
| ILC Legal Services LLP | | 2020 |
| Illanga Rays Ltd | Manufacturing | 2015 |
| Iltc Ltd | Wholesale & retail | 2023 |
| Iltoo Pharma UK Limited | Wholesale & retail | 2023 |
| Iltoo UK Limited | Wholesale & retail | 2023 |
| ILX2 Ltd | Real estate | 2023 |
| IM Hair Extensions UK Ltd | Other services | 2025 |
| Image & Motion Consultants Limited | Information & communication | 2007 |
| Image Interior Systems Holdings Ltd | Administrative & support | 2019 |
| Image Property Solutions Limited | Construction | 2015 |
| Imagination Aesthetics Limited | Health & social care | 2018 |
| Imaginative Reaction CIC | Administrative & support | 2023 |
| Imagine Kids Ltd | Education | 2018 |
| Imania Limited | Construction | 2016 |
| Imatter Health and Wellbeing Support CIC | Health & social care | 2022 |
| Imay Building Consultants Limited | Construction | 2022 |
| IMC Systems Development Ltd | Financial services | 2023 |
| Imcy Ltd | Other services | 2025 |
| Imeri H&S Partners Ltd | Professional & scientific | 2025 |
| IMG2014 Limited | Other services | 2018 |
| IMK Aycliffe Ltd | Real estate | 2024 |
| IMK Property Limited | Real estate | 2022 |
| Imka Consulting Limited | Professional & scientific | 2026 |
| Imkha Limited | Professional & scientific | 2008 |
| Immaculate Grounds Ltd | Professional & scientific | 2026 |
| Impact Accounting Solutions Ltd | Professional & scientific | 2025 |
| Impact Residential Limited | Real estate | 2017 |
| Impactful Governance - Community Interest Company | Professional & scientific | 2017 |
| Imperial Jewels Ltd | Wholesale & retail | 2025 |
| Imperial Weddings Ltd. | Other services | 2005 |
| Imperium Aerospace Limited | Professional & scientific | 2020 |
| Imperium Developers Ltd | Construction | 2018 |
| Imperium Properties Ltd | Real estate | 2020 |
| Impetus Occupational Therapy Ltd | Health & social care | 2022 |
| Impex Wines and Spirits Limited | Wholesale & retail | 2022 |
| Implant Solutions Direct Ltd | Wholesale & retail | 2018 |
| Implex Exports Limited | Wholesale & retail | 2005 |
| Impo-Expo Food Ltd | Wholesale & retail | 2019 |
| Imported Packaging Solutions Limited | Administrative & support | 2004 |
| Impressions of Time Ltd | Hospitality | 2016 |
| Impulse Trading Limited | Wholesale & retail | 2000 |
| Imran Advisory Group Ltd | Professional & scientific | 2026 |
| IMS Alpha Consulting Limited | Administrative & support | 2022 |
| IMS Internet Media Services Limited | Professional & scientific | 2010 |
| IMS Services London Limited | Information & communication | 2012 |
| IMS Solutions and Services Ltd. | Information & communication | 2013 |
| IN Therapy Ltd | Health & social care | 2026 |
| IN2WIN Limited | Extraterritorial | 2017 |
| IN8 Marketing Limited | Professional & scientific | 2012 |
| Inanswer AI Ltd | Information & communication | 2026 |
| Inara of London Ltd | Wholesale & retail | 2024 |
| Inaya Fresh Fish Limited | Wholesale & retail | 2025 |
| Inclusion & Resilience Research Hub CIC | Professional & scientific | 2024 |
| Inclusive Cultures Limited | Information & communication | 2005 |
| Inclusive Multi Academy Trust | Education | 2016 |
| Incrementum Ltd | Professional & scientific | 2022 |
| Independent Financial Advice Bureau (Watford) LLP | | 2014 |
| Independent Inspections (UK) Limited | Manufacturing | 2004 |
| Independent Mortgage Advice Bureau (Imab) Ltd | Financial services | 2006 |
| Independent Mortgage Advice Bureau (Stevenage) Ltd | Administrative & support | 2006 |
| Independent Mortgage Advice Bureau (Uxbridge) Ltd | Financial services | 2006 |
| Independent Neuropsychology Ltd | Health & social care | 2015 |
| Indesys Consulting Ltd | Professional & scientific | 2010 |
| INDIA2UK Ltd | Wholesale & retail | 2025 |
| Indian Food 1 Ltd | Hospitality | 2022 |
| Indian Sizzler Trading Limited | Hospitality | 2020 |
| Indicalabs PVT Ltd | Information & communication | 2010 |
| Indigo Clinic Ltd | Other services | 2025 |
| Indigo Properties & Management Ltd | Hospitality | 2026 |
| Indigo Rock Asset Management Limited | Real estate | 2025 |
| Indigo Rock Development Limited | Construction | 2025 |
| Indigo Rock Estates Limited | Real estate | 2024 |
| Indigo Stone Properties Ltd | Real estate | 2017 |
| Indigolodge Limited | Construction | 1994 |
| Indo Ceylone Ltd | Wholesale & retail | 2025 |
| Indo-Chi Kitchen Ltd | Hospitality | 2024 |
| Indurrah Management ( UK) Limited | Real estate | 1994 |
| Industrial Refrigeration Limited | Administrative & support | 2003 |
| Industryus Ltd | Education | 2025 |
| Ineeda Coffee Ltd | Manufacturing | 2017 |
| Infinite Computer Solutions Limited | Information & communication | 2004 |
| Infinite Connections Ltd | Professional & scientific | 2011 |
| Infinite Memories Ltd | Manufacturing | 2016 |
| Infinituum Limited | Professional & scientific | 2013 |
| Infinity 7 Investments Ltd | Real estate | 2020 |
| Infinity Financial Management Ltd | Professional & scientific | 2018 |
| Infinity Maths Ltd | Education | 2022 |
| Infintech Services Ltd | Information & communication | 2017 |
| Inflection ERP Limited | Information & communication | 2023 |