| Integral Bulk Packaging Ltd | Administrative & support | 2017 |
| Integral Care Solutions Limited | Health & social care | 2014 |
| Integral Development Solutions Limited | Construction | 2020 |
| Integral Electrical Solutions Limited | Construction | 2016 |
| Integral GAS Limited | Construction | 2023 |
| Integrated Group Services Limited | Information & communication | 1985 |
| Integrated Property Maintenance Ltd | Administrative & support | 2019 |
| Integrated Vehicle Technology Ltd. | Professional & scientific | 1999 |
| Integrative Supported Living Care Ltd | Health & social care | 2019 |
| Intellect Suites and Properties Limited | Real estate | 2022 |
| Intellectminds Consult Ltd | Professional & scientific | 2014 |
| Intellectual Mindset CIC | Education | 2026 |
| Intelligent 3D Consulting Ltd | Information & communication | 2018 |
| Intelligent Draughting Solutions Limited | Professional & scientific | 2016 |
| Intelligent Processes Ltd | Extraterritorial | 2012 |
| Intelligent Telemetry Limited | Manufacturing | 2008 |
| Intent 2 Improve Personal Training Ltd | Arts & recreation | 2017 |
| Intents Marquees Limited | Administrative & support | 2005 |
| Inter Co Solutions Ltd | Transport & logistics | 2023 |
| Inter Marine Logistics Ltd | Transport & logistics | 2017 |
| Intera Geosciences UK Limited | Professional & scientific | 2024 |
| Interactive Facilities Management Limited | Other services | 2000 |
| Interactive Services (UK) Ltd | Education | 2014 |
| Interactive Transaction Solutions Limited | Information & communication | 1990 |
| Intercar and Van Ltd | Wholesale & retail | 2021 |
| Intercard Group Ltd | Manufacturing | 2024 |
| Interdirect Limited | Information & communication | 1995 |
| Interiors DC Ltd | Construction | 2024 |
| Intermode UK Limited | Transport & logistics | 1999 |
| International Academy for Certified Disaster & Emergency Management, Criminology and Forensic Professionals - (Iacdecfp) UK, Limited | Information & communication | 2021 |
| International Business Studies Ltd | Education | 2023 |
| International Construction Group Ltd | Construction | 2017 |
| International Identification Database Management Inc Limited | Information & communication | 2023 |
| International Lighthouse CIC | Administrative & support | 2018 |
| International SCH of Leadership and Diplomacy Ltd | Administrative & support | 2024 |
| International Technology Ventures Limited | Wholesale & retail | 2023 |
| International Vapes and Shisha Limited | Wholesale & retail | 2025 |
| International Venture Holdings Limited | Financial services | 2019 |
| Internetwork Comms Limited | Information & communication | 2023 |
| Internetwork Media Holdings Ltd | Information & communication | 2025 |
| Internetwork Media Limited | Information & communication | 2000 |
| Internetwork Security Limited | Information & communication | 2013 |
| Interrodata Ltd | Information & communication | 2018 |
| Intervest Holdings UK Ltd | Financial services | 2025 |
| Interzon Ltd | Wholesale & retail | 2025 |
| Intject Ltd | Professional & scientific | 2019 |
| Intmar Ltd | Wholesale & retail | 2019 |
| Intok Limited | Wholesale & retail | 2019 |
| Intosert Limited | Professional & scientific | 1987 |
| Intothesticks.Life Ltd | Arts & recreation | 2021 |
| Intouch Monitoring Limited | Information & communication | 1998 |
| Intteco Limited | Wholesale & retail | 2013 |
| Intu K Ltd | Wholesale & retail | 2023 |
| Intuition Music MK Ltd | Education | 2014 |
| Intuitive Partners Ltd | Information & communication | 2016 |
| Invest in U Ltd | Other services | 2020 |
| Invest One Property Group Ltd | Real estate | 2018 |
| Investa Route Ltd | Households | 2019 |
| Investland Group Limited | Financial services | 1999 |
| Investment Club 3 Ltd | Financial services | 2023 |
| Investments TR Ltd | Real estate | 2022 |
| Investo Investment Ltd | Professional & scientific | 2025 |
| Investprim Limited | Construction | 2019 |
| Investright Real Estate Ltd | Real estate | 2023 |
| Invicta Leisure Limited | Extraterritorial | 2013 |
| Invictus Care Services Ltd | Health & social care | 2018 |
| Invictus Haulage Ltd | Transport & logistics | 2025 |
| Invictus Physio Care Ltd | Other services | 2025 |
| Invology Ltd | Information & communication | 2020 |
| Inwood Investments Limited | Professional & scientific | 2010 |
| Inwood Property Developments Limited | Real estate | 2003 |
| IO Pro Limited | Information & communication | 2017 |
| Ioan Stoica Ltd | Construction | 2021 |
| Iodine Limited | Construction | 2015 |
| ION Ambulance Care Ltd | Transport & logistics | 2014 |
| Ion's Driving School Limited | Education | 2013 |
| Iona Group Limited | Hospitality | 2026 |
| Ionas ION Ltd | Construction | 2025 |
| Ioncu Limited | Transport & logistics | 2020 |
| Ionel Butnaru Ltd | Administrative & support | 2016 |
| Ionel&Co Car Body Shop Limited | Wholesale & retail | 2024 |
| Ioni Logistic Ltd | Administrative & support | 2020 |
| Ionie Technologies Limited | Information & communication | 2007 |
| Ionut Delivery Dragan Ltd | Transport & logistics | 2025 |
| Ionutmd Ltd | Manufacturing | 2019 |
| Iosif Sardi Limited | Construction | 2016 |
| IP Matters Limited | Professional & scientific | 2016 |
| Ipeople Solutions Limited | Administrative & support | 2015 |
| IPP Drylining Ltd | Construction | 2021 |
| IPR License Ltd | Administrative & support | 2012 |
| Iprecedents Ltd | Information & communication | 2010 |
| Iproperty Finders Limited | Real estate | 2012 |
| Ipsa Limited | Information & communication | 1997 |
| Iqrisk Limited | Professional & scientific | 2017 |
| Irate Group IR Limited | Information & communication | 2025 |
| Irchester Residents Management Company Limited | Real estate | 2022 |
| Irem Bakery Ltd | Hospitality | 2026 |
| Irenyalum Limited | Health & social care | 2013 |
| Irinos Catering Ltd | Hospitality | 2018 |
| Iris Commercial & Domestic Cleaning Services Ltd | Administrative & support | 2022 |