| International Towbars Ltd | Wholesale & retail | 2023 |
| International Universities Strength and Conditioning Association | Professional & scientific | 2018 |
| Internetwork Communications Ltd | Information & communication | 2012 |
| Interneuron Group Limited | Financial services | 2024 |
| Interneuron Limited | Information & communication | 2019 |
| Interoperate Limited | Administrative & support | 2008 |
| Interquip Global Limited | Construction | 2019 |
| Interresolve Claims Limited | Administrative & support | 2008 |
| Interresolve Limited | Professional & scientific | 1996 |
| Interscopic Limited | Professional & scientific | 1946 |
| Intersection Change Ltd | Professional & scientific | 2020 |
| Intersection Healthcare Ltd | Health & social care | 2023 |
| Interserve Developments NO.1 Limited | Financial services | 2012 |
| Interserve Finance Limited | Administrative & support | 2008 |
| Interserve Group Holdings Limited | Financial services | 2007 |
| Interserve Group Limited | Financial services | 2019 |
| Interstellar Industries Limited | Manufacturing | 2020 |
| Interstellar Technologies Limited | Information & communication | 2015 |
| Intertrade Partners Limited | Wholesale & retail | 2018 |
| Interventions Consulting Limited | Professional & scientific | 2014 |
| Interworx Ltd | Manufacturing | 2018 |
| Intex Services Limited | Construction | 2016 |
| Intimalux Ltd | Wholesale & retail | 2025 |
| Intimas Limited | Transport & logistics | 1989 |
| Intime Homes Ltd | Real estate | 2024 |
| Intime Private Hire Ltd | Transport & logistics | 2025 |
| Intraa Ltd | Construction | 2015 |
| Intrakey Developments Limited | Information & communication | 1997 |
| Intralogica Solutions Limited | Information & communication | 2019 |
| Intricut Ltd | Arts & recreation | 2021 |
| Intrigue Fashions Ltd | Wholesale & retail | 2009 |
| Intrit Facilities Management Limited | Administrative & support | 2009 |
| Intro Hair & Beauty Ltd | Other services | 2016 |
| Intrpd Ltd | Wholesale & retail | 2024 |
| Intu Facilities Solutions Ltd | Administrative & support | 2022 |
| Intuitiq Limited | Information & communication | 2021 |
| Intuitive BI Limited | Extraterritorial | 2010 |
| Intuitive Business Intelligence Limited | Information & communication | 2010 |
| Intuitive Learning Limited | Information & communication | 2017 |
| Intune Psychology Limited | Education | 2022 |
| Intuo Hospitality Limited | Information & communication | 2023 |
| Intwest Ltd | Manufacturing | 2022 |
| INU Group Ltd | Real estate | 2024 |
| Invasive Land Remediation Ltd | Administrative & support | 2019 |
| Invasive Weed Management Franchising Limited | Administrative & support | 2021 |
| Invasive Weed Management Ltd | Agriculture & fishing | 2014 |
| Inve Limited | Hospitality | 2022 |
| Invenex Search Ltd | Administrative & support | 2023 |
| Invenia Group Limited | Administrative & support | 2009 |
| Inventive Ventures Ltd | Professional & scientific | 2021 |
| Inventory Programme Management Ltd | Wholesale & retail | 2020 |
| Inventry Holdings Ltd | Financial services | 2020 |
| Inventry Limited | Information & communication | 2010 |
| Invergare Properties Limited | Real estate | 2017 |
| Invergordon D GP Limited | Administrative & support | 2013 |
| Invergordon E GP LLP | | 2016 |
| Invergordon F GP LLP | | 2017 |
| Invergordon G LLP | | 2019 |
| Invergordon H LLP | | 2020 |
| Invergordon I LLP | | 2019 |
| Invergordon J LLP | | 2025 |
| Invergordon K LLP | | 2026 |
| Invergordon L LLP | | 2026 |
| Invergordon R Limited Partnership | | 2025 |
| Invergordon Z (Assetco) Limited | Administrative & support | 2026 |
| Invergrange Radiology Limited | Health & social care | 2020 |
| Inversiones Raudales Ltd | Hospitality | 2023 |
| Inversiones Rivera Ltd | Hospitality | 2024 |
| Inverted Spectrum Ltd | Information & communication | 2022 |
| Invest Consult Europe Ltd | Information & communication | 2015 |
| Invest in Citylife Limited | Real estate | 2019 |
| Invest Inc (Group) Limited | Real estate | 2018 |
| Invest Inc Management Limited | Construction | 2019 |
| Invest Leeds Limited | Real estate | 2016 |
| Invest Leisure Limited | Hospitality | 2020 |
| Invest Multilet & PPB Ltd | Real estate | 2021 |
| Invest North (Acquisitions) Limited | Real estate | 2021 |
| Invest North Limited | Real estate | 2012 |
| Invest North Property Ltd | Construction | 2021 |
| Invest UP Limited | Financial services | 2014 |
| Invest UP Nominees Limited | Information & communication | 2015 |
| Investium Capital Ltd | Financial services | 2023 |
| Investment (Midlands) Holdings Limited | Financial services | 2009 |
| Investment Champion Online Limited | Financial services | 2012 |
| Investment Properties (Leeds) Limited | Real estate | 2007 |
| Investment Shares Limited | Wholesale & retail | 2024 |
| Investments in Education Limited | Administrative & support | 2007 |
| Investors in Health (C&T) Holdings Limited | Administrative & support | 2004 |
| Investors in Health (C&T1) Limited | Administrative & support | 2004 |
| Investors in the Community (Bexley Schools) Limited | Administrative & support | 2002 |
| Investors in the Community (Buxton) Limited | Administrative & support | 2001 |
| Investors in the Community (Leeds Schools) Holding Company Limited | Professional & scientific | 2005 |
| Investors in the Community (Leeds Schools) Limited | Administrative & support | 2005 |
| Investors in the Community (Leeds Schools) Subdebt Limited | Administrative & support | 2005 |
| Investpro Limited | Administrative & support | 2019 |
| Investwide Limited | Real estate | 2004 |
| Invicta Forks & Attachments Limited | Manufacturing | 2015 |
| Invicta Group Holdings Ltd | Wholesale & retail | 2024 |
| INVIGOR8 LLP | | 2008 |
| Invigorate Face Ltd | Health & social care | 2017 |