| Ignite Brandworks Ltd | Professional & scientific | 2024 |
| Igtham Holdings Limited | Financial services | 2021 |
| Ihsan’S Limited | Hospitality | 2026 |
| Iiza Construction Limited | Construction | 2015 |
| IJ Mobile Repair Ltd | Wholesale & retail | 2019 |
| IJB Healthcare Ltd. | Health & social care | 2017 |
| IJJ Company Ltd | Professional & scientific | 2020 |
| IJR Interior Limited | Construction | 2013 |
| IKA Construction Ltd | Construction | 2018 |
| Iknowa ADR Limited | Education | 2024 |
| Iknowa Consumer Code Limited | Financial services | 2023 |
| Iknowa Infrastructure Advisory Group Ltd | Financial services | 2026 |
| Iknowa Shared Services Limited | Professional & scientific | 2026 |
| Iknowa Technology Limited | Financial services | 2023 |
| Ikos Properties Ltd | Real estate | 2023 |
| Ilford Wanderers Rugby Football Club Limited | Hospitality | 2011 |
| Ilhami Chef Ltd | Hospitality | 2026 |
| Illustrated by Weezy Ltd | Professional & scientific | 2024 |
| IM Dental Care Limited | Health & social care | 2015 |
| Imagematic Limited | Health & social care | 2000 |
| Impact Care Holdings Limited | Financial services | 2024 |
| Impact Care Limited | Health & social care | 2016 |
| Impactwin Partner Ltd | Manufacturing | 2016 |
| Imperial Social Media Ltd | Professional & scientific | 2025 |
| Imursif Limited | Information & communication | 2020 |
| IN & OUT (UK) Ltd. | Real estate | 1999 |
| IN DI Street Entertainment Limited | Arts & recreation | 2025 |
| IN the Mane Limited | Extraterritorial | 2024 |
| Inalgesco Ltd | Manufacturing | 2020 |
| Inbright Contractors Ltd | Construction | 2010 |
| Independentpersons Ltd | Administrative & support | 2025 |
| Indi's Lash & Beauty Ltd | Other services | 2025 |
| Indigo Array Ltd | Information & communication | 2016 |
| Industrial Boiler Management Limited | Administrative & support | 2022 |
| Infenics Limited | Administrative & support | 2018 |
| Infinite Property Management Ltd | Real estate | 2020 |
| Infinity N Beyond Events Ltd | Arts & recreation | 2021 |
| Infinityhub UK Ltd | Wholesale & retail | 2026 |
| Inflex Electrical Ltd | Construction | 2014 |
| Inforoot Ltd | Wholesale & retail | 2018 |
| Infosight Consultancy Limited | Information & communication | 2012 |
| Initiate Productions Ltd | Arts & recreation | 2025 |
| Initium Construction Ltd | Construction | 2025 |
| Inkom Ltd | Construction | 2021 |
| Inkubee Ltd | Professional & scientific | 2021 |
| Inline Electrical Limited | Manufacturing | 2017 |
| Inner Purpose Limited | Other services | 2018 |
| Inner Space Decorating Ltd | Construction | 2026 |
| Innovative Medicare Limited | Administrative & support | 2018 |
| Innovative Signs Limited | Other services | 2022 |
| Inovation by RBT Ltd | Public administration | 2025 |
| Inovative Housing Limited | Real estate | 2024 |
| Inrealty Ltd | Real estate | 2023 |
| Inspect Elect Limited | Construction | 1999 |
| Inspiration Build Ltd | Construction | 2025 |
| Inspire to Sign Ltd | Education | 2023 |
| Inspired Wood Ltd | Wholesale & retail | 2013 |
| Inspiro Education Consultancy Ltd | Education | 2019 |
| Insta Care Ltd | Health & social care | 2024 |
| Instagas & Heating Services Ltd | Construction | 2022 |
| Install GAS Fitters Ltd | Professional & scientific | 2023 |
| Instant Mortgage Solutions Limited | Financial services | 2020 |
| Instant R Ltd | Transport & logistics | 2022 |
| Insulation Element Ltd | Construction | 2025 |
| Insurance Accounting and Compliance Ltd | Professional & scientific | 2013 |
| INT Superstore 2 Ltd | Wholesale & retail | 2021 |
| Integral Smoke and Fire Solutions Ltd | Construction | 2025 |
| Integral Solutions MEP Group Limited | Financial services | 2022 |
| Integral Solutions MEP Limited | Construction | 2014 |
| Integral Solutions MEP Residential Ltd | Construction | 2022 |
| Integrated Financial Solutions (UK) Limited | Financial services | 1999 |
| Integrated People Solutions Ltd | Administrative & support | 2023 |
| Intellitext Ltd | Education | 2025 |
| Inter Actum Ltd | Professional & scientific | 2020 |
| Interface Supported Living Ltd | Health & social care | 2019 |
| Interior Pro-Build Services Limited | Construction | 2016 |
| Interlec Renewable Energy Ltd | Construction | 2024 |
| Internal Talent Partners Limited | Administrative & support | 2021 |
| International Movement for Tamil Culture Imtc | Education | 2020 |
| Internet Traffic Ltd | Information & communication | 2013 |
| Intertronic Solutions Limited | Information & communication | 2010 |
| Intex Services Group Ltd | Transport & logistics | 2026 |
| Intexco Build Ltd | Administrative & support | 2022 |
| Intexco Design Limited | Administrative & support | 2008 |
| Intexco Holdings Limited | Administrative & support | 2022 |
| Intown Property Services Ltd | Construction | 2020 |
| Introline Properties Limited | Construction | 1992 |
| Inuvil Onrium U.K | Extraterritorial | 2012 |
| INV Capital Limited | Real estate | 2019 |
| Invenio Information Management Ltd | Information & communication | 2025 |
| Inventify Ltd | Wholesale & retail | 2023 |
| Invescap Ltd | Professional & scientific | 2013 |
| Invisij Limited | Professional & scientific | 2018 |
| IOL Limited | Information & communication | 2020 |
| Ipseita Limited | Information & communication | 2017 |
| IQ Brickwork Limited | Construction | 2023 |
| IQ Repairs Limited | Other services | 2023 |
| Iqra: Read in the Name of Allah Ltd | Extraterritorial | 2011 |
| IRL Group Limited | Construction | 1991 |
| IRL Holdings Limited | Professional & scientific | 2004 |