| Infinitelife Real Estates Ltd | Real estate | 2026 |
| Infinity Diadem Limited | Health & social care | 2021 |
| Infinity Drones Ltd | Professional & scientific | 2024 |
| Inflatables Limited | Extraterritorial | 2021 |
| Info Green Limited | Professional & scientific | 2022 |
| Infobee Consulting Limited | Information & communication | 2022 |
| Infoclaruz Ltd | Information & communication | 2010 |
| Infolens Limited | Information & communication | 2011 |
| Information Grid Ltd. | Information & communication | 2017 |
| Infosecworld Limited | Information & communication | 2017 |
| Ingatestone Developments Limited | Construction | 2006 |
| Ingatestone Governance and Compliance Limited | Financial services | 2010 |
| Ingenious Data Consulting Limited | Professional & scientific | 2024 |
| Ingenious Pixies Ltd | Information & communication | 2024 |
| Ingenti Limited | Professional & scientific | 2024 |
| Ingleton 7 Limited | Real estate | 2014 |
| Ingleton Group Limited | Construction | 2020 |
| Ingleton Homes Limited | Construction | 2020 |
| Ingleton Properties Limited | Construction | 1994 |
| Ingram Services Limited | Professional & scientific | 1998 |
| Ingrave House Rentals Limited | Construction | 2022 |
| Inisop Ltd | Information & communication | 2020 |
| INK in Bloom Ltd | Arts & recreation | 2024 |
| Inkwell Insights Limited | Wholesale & retail | 2025 |
| Inlightened Limited | Real estate | 2025 |
| Inline Logistics Limited | Professional & scientific | 1991 |
| Innasol Group Ltd | Professional & scientific | 2013 |
| Innasol Heat POD Ltd | Manufacturing | 2011 |
| Innasol Ltd | Administrative & support | 2010 |
| Innasol SPV1 Limited | Energy | 2025 |
| Innasol Super Power One Ltd | Energy | 2017 |
| Inner Circle Essex Ltd | Arts & recreation | 2023 |
| Inner Circle Property Limited | Administrative & support | 2026 |
| Inner City Plumbers Ltd | Construction | 2016 |
| Inner London Maintenance Limited | Construction | 2010 |
| Innovation Capital Advisory Ltd | Financial services | 2025 |
| Innovation Properties and Lettings Ltd | Real estate | 2021 |
| Innovations by Simply Limited | Information & communication | 2022 |
| Innovative Product Designs Ltd | Manufacturing | 2011 |
| Innovision Global Consulting Ltd | Professional & scientific | 2014 |
| Innoweb Ventures Ltd | Information & communication | 2024 |
| Innrcircle Ltd | Administrative & support | 2023 |
| Inovanta Limited | Professional & scientific | 1999 |
| Insaga Ltd | Professional & scientific | 2017 |
| Insaga Properties Ltd | Real estate | 2021 |
| Inscribe Creative Limited | Professional & scientific | 2009 |
| Inside News Limited | Administrative & support | 2007 |
| Insight and Impact Ltd | Professional & scientific | 2025 |
| Insightful Systems Ltd | Professional & scientific | 2010 |
| Inspection Services Limited | Professional & scientific | 2004 |
| Inspirational Training Solutions Limited | Education | 2011 |
| Inspire Wellbeing Services Community Interest Company | Health & social care | 2019 |
| Inspired Consultancy Solutions Ltd | Professional & scientific | 2021 |
| Inspiring Support Solutions Limited | Administrative & support | 2022 |
| Instrument Management Solutions Limited | Other services | 2015 |
| Instruments of the Arcane Limited | Wholesale & retail | 2021 |
| Insure Telematics Solutions Limited | Financial services | 2013 |
| Integ Limited | Administrative & support | 2024 |
| Integra Business Technology Limited | Wholesale & retail | 2026 |
| Integra Cleaning Group Limited | Administrative & support | 2018 |
| Integra Data Solutions Limited | Professional & scientific | 2019 |
| Integrated Leadership Coaching Ltd | Professional & scientific | 2024 |
| Integrated Mobile Solutions Limited | Information & communication | 2019 |
| Integrity Films Limited | Information & communication | 2021 |
| Intelek Limited | Professional & scientific | 1949 |
| Intelek Pension Trustees Limited | Professional & scientific | 1983 |
| Intelianalytics Limited | Information & communication | 2023 |
| Intellectual Business Services UK Ltd | Professional & scientific | 2016 |
| Intellectual Services Ltd | Information & communication | 2019 |
| Intellego Financial Planning Ltd | Financial services | 2024 |
| Intellifit Ltd | Manufacturing | 2016 |
| Intelmedix Resourcing Ltd | Administrative & support | 2023 |
| Intense Records Limited | Wholesale & retail | 2025 |
| Intentional Living Consultancy Ltd | Education | 2024 |
| Inter Market Derivatives Limited | Administrative & support | 2001 |
| Inter Yola Co Ltd | Wholesale & retail | 2019 |
| Interacss Limited | Professional & scientific | 2004 |
| Interact Chelmsford Limited | Education | 1995 |
| Intercools Holdings Ltd | Financial services | 2026 |
| Interglobe Imports & Exports Ltd | Wholesale & retail | 2004 |
| Intergroup Global Forwarding Ltd | Transport & logistics | 2023 |
| Interhold Holdings Ltd | Financial services | 2022 |
| Interim FC Ltd | Professional & scientific | 2025 |
| Interior Fit-Out Services Ltd | Construction | 2021 |
| Interiordeluxe Limited | Wholesale & retail | 2025 |
| Interlock Logistics Ventures Limited | Financial services | 2025 |
| International Bible Students Association | Other services | 1914 |
| International Bridge Excellence Limited | Information & communication | 2020 |
| International Drinks Agency Limited | Wholesale & retail | 2011 |
| International Green Shipping and Trading Ltd | Administrative & support | 2020 |
| International Horseracing Lottery Ltd | Extraterritorial | 2001 |
| International Hotel Awards Ltd | Professional & scientific | 2010 |
| International Hotel Property Ltd | Real estate | 2009 |
| International Marketing Partners Limited | Professional & scientific | 1996 |
| International Pathway Limited | Arts & recreation | 2023 |
| International Property Awards Licensing Limited | Administrative & support | 2016 |
| International Property Awards Limited | Information & communication | 2000 |
| International Property Media Limited | Information & communication | 1989 |
| International Salvage Union | Other services | 2009 |
| International Society for the Study of Emerging Drugs CIC | Other services | 2020 |