| Interlink Real Estate Investments UK Ltd | Real estate | 2024 |
| Interlink Services Ltd | Construction | 2015 |
| Interlock Flexible Products Limited | Manufacturing | 1995 |
| Interlock Metal Products Limited | Extraterritorial | 1997 |
| Interlok Group Limited | Other services | 2023 |
| Intermediary Management Limited | Information & communication | 2006 |
| International Artists Limited | Extraterritorial | 2017 |
| International Assets and Investments Limited | Real estate | 2025 |
| International Association of Management Accountants | Education | 2024 |
| International Association of Qualified Accountants Ltd | Professional & scientific | 2017 |
| International Builders Limited | Construction | 2024 |
| International Building Press C.I.C. | Professional & scientific | 2025 |
| International Car Exports Limited | Wholesale & retail | 2011 |
| International Cargo Limited | Transport & logistics | 2008 |
| International Christian Youthworks Ministries Limited | Extraterritorial | 2013 |
| International Compliance Association Limited | Professional & scientific | 2002 |
| International Council of Tanners | Professional & scientific | 2012 |
| International Currency Exchange (U.K) Ltd. | Extraterritorial | 2012 |
| International Currency Exchange Limited | Administrative & support | 1986 |
| International Day of Birmingham CIC | Arts & recreation | 2025 |
| International Deal Network LLP | | 2015 |
| International Education Academy Ltd | Education | 2023 |
| International Education and Business Solutions Limited | Administrative & support | 2018 |
| International Educational Links Ltd | Professional & scientific | 2010 |
| International Export and Import Limited | Wholesale & retail | 2010 |
| International Junior Golf Academy Limited | Wholesale & retail | 2025 |
| International Kashmir Rural AID Ltd | Other services | 2013 |
| International Language Centre Limited | Administrative & support | 2014 |
| International Link Services Limited | Wholesale & retail | 2003 |
| International Mass Private Limited | Agriculture & fishing | 2025 |
| International Medical Professions Association Ltd | Health & social care | 2024 |
| International Mining & Infrastructure Corporation PLC | Mining & quarrying | 2004 |
| International Motorcyclists Tour Club | Other services | 2012 |
| International Moving Expert Limited | Transport & logistics | 2018 |
| International Nanny Consultancy Ltd | Households | 2023 |
| International Nanny Ltd | Households | 2016 |
| International Nepal Fellowship | Health & social care | 1995 |
| International OFF Licence Rose Ltd | Wholesale & retail | 2025 |
| International Proinvestments Limited | Real estate | 2025 |
| International School of Business and Technology Ltd | Education | 2025 |
| International Share Health | Health & social care | 2009 |
| International Sprout Holdings Ltd | Wholesale & retail | 2025 |
| International Super Ltd | Wholesale & retail | 2019 |
| International Synergies Limited | Professional & scientific | 2005 |
| International Trading and Consulting Services Ltd | Professional & scientific | 2024 |
| International Umbrella Limited | Financial services | 2011 |
| International Visual Arts Exchange CIC | Arts & recreation | 2024 |
| International Waqf Fund | Financial services | 2013 |
| International Warrior Academy Ltd | Education | 2025 |
| International Windows Limited | Manufacturing | 2026 |
| International Wrought Copper Council | Other services | 2013 |
| Internet Cable Ltd. | Wholesale & retail | 2023 |
| Internet Marketing and Events Management Ltd | Professional & scientific | 2024 |
| Internet Tax Company Limited | Professional & scientific | 1999 |
| Internet UP Ltd | Wholesale & retail | 2025 |
| Interpreting & Translation Enterprise Ltd | Professional & scientific | 2022 |
| Interpreting Signvox Languages Ltd | Professional & scientific | 2025 |
| Interserve Holdings Limited | Financial services | 1930 |
| Interserve International Fellowship | Other services | 2018 |
| Interservice Logistics Ltd | Construction | 2022 |
| Interstellar Fella Ltd | Information & communication | 2025 |
| Interstellar Group Limited | Financial services | 2016 |
| Interstellar Homes Limited | Real estate | 2022 |
| Intersteller Sellers Ltd | Wholesale & retail | 2021 |
| Intertool Limited | Wholesale & retail | 1984 |
| Intervention Architecture Ltd | Professional & scientific | 2014 |
| Interventional Radiology Limited | Health & social care | 2010 |
| Interview a Ltd | Information & communication | 2026 |
| Interware Ltd | Information & communication | 2017 |
| Interweave Software Limited | Information & communication | 2025 |
| Interweb Media Design Limited | Information & communication | 2014 |
| Intesys Limited | Professional & scientific | 1992 |
| Intex Hall and Graham Ltd | Construction | 2006 |
| Intima Textiles Limited | Wholesale & retail | 1994 |
| Intimate Events Studio Ltd | Administrative & support | 2026 |
| Into the White Ltd | Administrative & support | 2011 |
| Intogreat Housing and Support Services CIC | Health & social care | 2025 |
| Intogreat Housing Ltd | Hospitality | 2024 |
| Intorno Inter LP | | 2015 |
| Intown Materials Ltd | Wholesale & retail | 2026 |
| Intra Energy Limited | Professional & scientific | 2024 |
| Intra Strukt CS Limited | Wholesale & retail | 2025 |
| Intrada Software Ltd | Information & communication | 2024 |
| Intraveland Ltd | Professional & scientific | 2026 |
| Intrepia Ltd | Information & communication | 2014 |
| Intrepid Technology Limited | Wholesale & retail | 1998 |
| Intrepid Venture Ltd | Wholesale & retail | 2023 |
| Intrinsic (Homebuy) Limited | Financial services | 2014 |
| Intrinsic Corporate Solutions Ltd | Real estate | 2019 |
| Intrinsic Eco Energy Limited | Construction | 2024 |
| Intrinsic Equity Limited | Professional & scientific | 2002 |
| Ints UK Limited | Wholesale & retail | 2006 |
| Intsonic Limited | Professional & scientific | 2017 |
| Intuch Limited | Administrative & support | 2021 |
| Intuitive Cloud Management Ltd | Information & communication | 2024 |
| Intuprint Holdings Limited | Financial services | 2018 |
| Intution Limited | Education | 2016 |
| Inunity Ltd | Arts & recreation | 2011 |
| Invacore Limited | Information & communication | 2010 |
| Invasive Vegetation Management and Treatment Limited | Administrative & support | 2007 |