| Inspiring Goals Ltd | Arts & recreation | 2013 |
| Inspirit Developments Ltd | Real estate | 2021 |
| Insta Energy 67 Ltd | Energy | 2025 |
| Install Your Bathroom Limited | Construction | 2019 |
| Installation, Testing & Commissioning UK Ltd | Construction | 2016 |
| Instant Bathrooms & Tiles Ltd | Wholesale & retail | 2025 |
| Instant Care Ltd | Administrative & support | 2017 |
| Instant Investments (NW) Ltd | Real estate | 2025 |
| Instant Plumbing & Heating Supplies Ltd | Wholesale & retail | 2016 |
| Instant Property (Northwest) Ltd | Real estate | 2019 |
| Instant Tyre Solutions Ltd | Wholesale & retail | 2024 |
| Instone Homes Limited | Real estate | 2010 |
| Instruments to Industry Limited | Manufacturing | 2023 |
| Insync IT Limited | Information & communication | 2012 |
| Insyte IQ Limited | Other services | 2023 |
| Inta Leisure Limited | Hospitality | 2013 |
| Intact Energy Limited | Professional & scientific | 2018 |
| Intake Property Ltd | Real estate | 2023 |
| Integral Building Systems Ltd | Information & communication | 2024 |
| Integrated Corporate Risk Management Ltd | Professional & scientific | 2003 |
| Integrity Auto Group Limited | Wholesale & retail | 2026 |
| Intelatech Limited | Wholesale & retail | 2018 |
| Intelinsure Limited | Administrative & support | 2020 |
| Intelleon AI Limited | Wholesale & retail | 2025 |
| Intelligent Development Limited | Professional & scientific | 2003 |
| Intelligent Kitchen Ventilation Limited | Extraterritorial | 2009 |
| Intellinsure Limited | Administrative & support | 2020 |
| Intelpro Limited | Real estate | 2020 |
| Intelum Ltd | Financial services | 2015 |
| Inter Retail Limited | Wholesale & retail | 2014 |
| Interconect Ltd | Wholesale & retail | 2019 |
| Interface Solutions UK Limited | Administrative & support | 2007 |
| Intergame Events Limited | Administrative & support | 2018 |
| Intergame Holdings Limited | Financial services | 2002 |
| Intergame Limited | Information & communication | 1994 |
| Interiore Ltd. | Administrative & support | 2014 |
| Intermediation Services Ltd. | Extraterritorial | 2023 |
| International Aero Maintenance Ltd | Manufacturing | 2019 |
| International Central Ltd | Wholesale & retail | 2025 |
| International Standard Bureau Ltd. | Administrative & support | 2009 |
| Internationalbeverageslimited Ltd | Wholesale & retail | 2025 |
| Interpix Ltd | Manufacturing | 2007 |
| Interpreters & Translators Ltd | Administrative & support | 2013 |
| Interpreting Services Ltd | Professional & scientific | 2013 |
| Interurban Limited | Real estate | 1985 |
| Interwest Property Holding Ltd | Financial services | 2026 |
| Intex Construction Ltd | Construction | 2026 |
| Inthebackgroundva Ltd | Administrative & support | 2026 |
| Intimacy Insights Ltd | Health & social care | 2024 |
| Intl. Aero Maintenance Ltd | Manufacturing | 2024 |
| Intled IO PVT Ltd | Education | 2026 |
| Intouch Fire & Security Ltd | Manufacturing | 2011 |
| Intraquest Community CIC | Health & social care | 2013 |
| Intraquest Neuro Ltd | Education | 2023 |
| Introducing Events Ltd | Administrative & support | 2022 |
| Intuition Bmhc Ltd | Education | 2025 |
| Invest & Services Ltd | Wholesale & retail | 2017 |
| Invest in Care 2 Ltd | Health & social care | 2024 |
| Invest Peek Limited | Information & communication | 2023 |
| Investa Capital Advisors Ltd | Administrative & support | 2017 |
| Investa Group Limited | Financial services | 2016 |
| Investment Real Estate Ltd | Construction | 2017 |
| Investment Risk Management Ltd | Administrative & support | 2009 |
| Investment&Business Ltd. | Financial services | 2023 |
| Investmo Limited | Real estate | 2026 |
| Investwise Properties Ltd | Real estate | 2022 |
| Invicta Development Consultancy Ltd | Real estate | 2014 |
| Invictus Management Consultants Limited | Professional & scientific | 2019 |
| Invovibe Tech Ltd | Information & communication | 2025 |
| IOM Ventures Ltd | Hospitality | 2026 |
| ION Electrix Ltd | Construction | 2020 |
| ION Plumbing Ltd | Construction | 2024 |
| ION67 Ltd | Transport & logistics | 2021 |
| Ionflow Electricals Limited | Manufacturing | 2023 |
| Ipartysupplies Ltd | Wholesale & retail | 2024 |
| IPG Pipework & Welded Fabrications Ltd | Manufacturing | 2005 |
| Ips-Vss Ltd | Administrative & support | 2022 |
| Ipure Nutrition Limited | Manufacturing | 2014 |
| Iqbal Urdu Foundation Community Interest Company | Other services | 2015 |
| IR35 MA Locum Ltd | Health & social care | 2026 |
| Irah Property Solutions Ltd | Real estate | 2024 |
| IRB GAS Services Ltd | Professional & scientific | 2019 |
| IRB Group Ltd | Professional & scientific | 2025 |
| Irfa Property Ltd | Real estate | 2025 |
| Irfan ALI Nusrat Ltd | Wholesale & retail | 2025 |
| IRK NW Ltd | Real estate | 2025 |
| Iroko Healthcare Services Ltd | Health & social care | 2025 |
| Ironguarding Solutions Ltd | Administrative & support | 2023 |
| Irving Media Limited | Information & communication | 2010 |
| Irwell Property Services Ltd | Real estate | 2020 |
| Irwell Stays Property Management Ltd | Real estate | 2022 |
| IS Vision Ltd | Health & social care | 2024 |
| ISA Builders (Oldham) Limited | Construction | 2021 |
| Isaac HSM Ltd | Real estate | 2023 |
| Isaan Aspire CIC | Education | 2025 |
| Isaan Martial Arts Ltd | Arts & recreation | 2018 |
| Isecurity Solutions (UK) Ltd | Administrative & support | 2010 |
| Iside Wine Ltd | Wholesale & retail | 2022 |
| Isio Media Limited | Information & communication | 2024 |
| Island Accounting Ltd | Professional & scientific | 2017 |