| International College of Islamic Sciences London Ltd | Education | 2025 |
| International Company MAN LLP | | 2024 |
| International Creativity Academy Limited | Education | 2025 |
| International Develop Learning Instruction Limited | Education | 2021 |
| International Electric Projects Ltd | Professional & scientific | 2025 |
| International Fertility Company Ltd | Information & communication | 2017 |
| International Financial Services London Ltd | Professional & scientific | 2018 |
| International Forensic Engineers Ltd | Professional & scientific | 2020 |
| International Halal Trust | Administrative & support | 2021 |
| International Healthcare Resourcing Limited | Administrative & support | 2013 |
| International Immo Invest Ltd | Financial services | 2017 |
| International Immobilien Service Ltd | Administrative & support | 2014 |
| International Influence Hub Ltd | Information & communication | 2023 |
| International Investment Bureau Ltd | Professional & scientific | 2014 |
| International Jorel Found Limited | Professional & scientific | 2025 |
| International Justice Organization in London Ltd | Public administration | 2025 |
| International Land & Marine Engineers Limited | Information & communication | 1991 |
| International Land Development Construction and Civil Engineering Limited | Construction | 2018 |
| International Learning Exchange Programme Limited | Education | 2021 |
| International Legal English Limited | Professional & scientific | 2012 |
| International Links (Global) Ltd | Education | 2018 |
| International Marine Engineering Specialists Ltd | Administrative & support | 2016 |
| International Media Labs PC | | 2016 |
| International Medical Group Holdings Limited | Financial services | 2016 |
| International Medical Group Limited | Financial services | 2001 |
| International Organization for Complementary and Alternative Medicine Ltd | Education | 2024 |
| International Packaging Solutions Limited | Manufacturing | 2001 |
| International Passage Trading Ltd | Wholesale & retail | 2025 |
| International Peer Assist Aviation Coalition Ltd | Health & social care | 2023 |
| International PRE Schools Ltd | Education | 2019 |
| International RC Company Ltd | Health & social care | 2019 |
| International Recruitment PVT Ltd | Information & communication | 2019 |
| International Research Publisher (IRP) Limited | Information & communication | 2021 |
| International Resource Corporation Ltd | Wholesale & retail | 2014 |
| International Seasonings Limited | Wholesale & retail | 2020 |
| International Sports Tax Association Limited | Other services | 2022 |
| International Steel Inspection Ltd | Professional & scientific | 2025 |
| International Student Guardianship & Education Services Limited | Education | 2020 |
| International Student Study Centres Limited | Administrative & support | 2017 |
| International TY Market Ltd | Wholesale & retail | 2025 |
| International Union of Academics, Researchers and Specialized Trainers Ltd | Education | 2025 |
| Internet Security Ltd | Information & communication | 2020 |
| Internet Services (EU) Limited | Information & communication | 2004 |
| Internet Supermarket Ltd | Information & communication | 2017 |
| Internet Trade Limited | Wholesale & retail | 2013 |
| Internos Management Limited | Professional & scientific | 2018 |
| Interplan Contracts Ltd | Construction | 2013 |
| Interplan Fit-Out Ltd | Construction | 2018 |
| Interpretations Services Ltd | Administrative & support | 2017 |
| Interservice DNS Limited | Construction | 2018 |
| Interstate Investments Ltd | Real estate | 2019 |
| Interstrand Projects Limited | Real estate | 2022 |
| Intervia Ltd | Wholesale & retail | 2025 |
| Interweld Nuclear Services Ltd | Construction | 2024 |
| Intesa (Leicester) Ltd | Administrative & support | 2019 |
| Intevia Group Ltd | Information & communication | 2025 |
| Intezio Worldwide Limited | Information & communication | 2025 |
| Intfcat Mart Ltd | Wholesale & retail | 2025 |
| Inthebathroom Limited | Wholesale & retail | 2010 |
| Inthera Ltd | Health & social care | 2021 |
| Intimate Education Limited | Education | 2021 |
| Intiox Ltd | Manufacturing | 2018 |
| Intisby (International) Electrical Technology Group Co., Ltd | Manufacturing | 2021 |
| Intl Certification Limited | Professional & scientific | 2023 |
| Intl Commerce Management Ltd | Professional & scientific | 2013 |
| Into Cool Consultancy Limited | Professional & scientific | 2024 |
| Into Investments London Ltd | Financial services | 2019 |
| Intosol Holdings PLC | Professional & scientific | 2017 |
| Intra Properties Limited | Real estate | 2024 |
| Intra Telecare Limited | Administrative & support | 2015 |
| Intraberg PC | | 2018 |
| Intracare Limited | Information & communication | 2013 |
| Intraders Ltd | Wholesale & retail | 2018 |
| Intramay Limited | Information & communication | 2024 |
| Intravenous Solutions Ltd | Health & social care | 2020 |
| Intrinsic Flow Ltd | Information & communication | 2018 |
| Intrld Limited | Other services | 2025 |
| Introlet Limited | Real estate | 2017 |
| Introteach Limited | Administrative & support | 2015 |
| Intruder Watch Limited | Administrative & support | 2019 |
| Intua Ltd | Information & communication | 2026 |
| Intuitive Early Years Ltd | Education | 2018 |
| Intustudios Ltd | Arts & recreation | 2025 |
| Invari Group Ltd | Information & communication | 2025 |
| Inven Green Recycling Ltd | Water & waste | 2020 |
| Inventables Ltd | Wholesale & retail | 2015 |
| Inventaria Co Ltd | Households | 2019 |
| Invention Technology (U.K.) Limited | Professional & scientific | 2008 |
| Inventive Interiors Ltd | Professional & scientific | 2016 |
| Inventive Medical Limited | Education | 2008 |
| Inventive Travel Ltd | Administrative & support | 2025 |
| Inventorx Technologies Ltd | Information & communication | 2025 |
| Inventory Control Systems Limited | Professional & scientific | 2025 |
| Inventory Management Online Ltd | Administrative & support | 2015 |
| Inventra Vision Ledger Ltd | Information & communication | 2025 |
| Inverley Ltd | Wholesale & retail | 2026 |
| Invermead Ltd | Information & communication | 2014 |
| Inverness Bars Ltd | Administrative & support | 2016 |
| Invest Construction Africa Ltd | Financial services | 2022 |
| Invest Properties Ltd | Extraterritorial | 2021 |