| Inshoeition Limited | Wholesale & retail | 2019 |
| Inside-Out People Development Partners Limited | Professional & scientific | 2022 |
| Insight by SY Limited | Professional & scientific | 2024 |
| Insightful Corporate Finance Limited | Professional & scientific | 2024 |
| Insightful Recruitment Ltd | Administrative & support | 2025 |
| Insights Global Ltd | Professional & scientific | 2025 |
| Insley Digital Ltd | Professional & scientific | 2020 |
| Insley Estates Holdings Ltd | Financial services | 2022 |
| Insley Estates Ltd | Real estate | 1987 |
| Insley Family Ltd | Professional & scientific | 2025 |
| Inspire Accountants Ltd | Professional & scientific | 2024 |
| Inspire CBT Limited | Health & social care | 2018 |
| Inspire Consulting Services Ltd | Information & communication | 2013 |
| Inspire Delivery Solution Limited | Professional & scientific | 2016 |
| Inspire Furniture Hire Limited | Other services | 2007 |
| Inspire Performance Psychology Limited | Arts & recreation | 2026 |
| Inspire Property Management Limited | Real estate | 2011 |
| Inspired Collaboration Ltd | Professional & scientific | 2020 |
| Inspired Funnels Limited | Information & communication | 2023 |
| Inspired Traders Ltd | Wholesale & retail | 2024 |
| INSTAKICKSZ247 Limited | Wholesale & retail | 2021 |
| Institute of Payroll Professionals | Education | 1997 |
| Intastream Limited | Health & social care | 2025 |
| Integrate Engineering Resources Ltd | Administrative & support | 2015 |
| Integrate Hope CIC | Education | 2024 |
| Integrate Property Investments Ltd | Real estate | 2019 |
| Integrated DNA Technologies UK, Ltd | Wholesale & retail | 2015 |
| Integrationers Limited | Information & communication | 2020 |
| Integrecty Limited | Administrative & support | 2026 |
| Integricore Consulting Ltd | Information & communication | 2024 |
| Integrus Global Limited | Information & communication | 2006 |
| Intelex Systems Limited | Information & communication | 2008 |
| Intellect Mind Tech Limited | Information & communication | 2009 |
| Intelliga Care Ltd | Real estate | 2025 |
| Intelligencia Limited | Other services | 2025 |
| Intelligent Business Systems Ltd | Information & communication | 2004 |
| Intelligent Logistics Solutions Ltd | Transport & logistics | 2026 |
| Intelligent Mass Spec Solutions Limited | Professional & scientific | 2025 |
| Intelligent Telecommunications Ltd | Information & communication | 2012 |
| Intelligent Widget Ltd | Wholesale & retail | 2024 |
| Intelligentsia SR Limited | Information & communication | 2025 |
| Intellisell Limited | Information & communication | 2007 |
| Intelliweave Ltd | Information & communication | 2026 |
| Inter Continental Logistics Limited | Transport & logistics | 2006 |
| Interactive Software Limited | Information & communication | 1992 |
| Interface Data Power Limited | Construction | 2024 |
| Interface Developers Ltd. | Information & communication | 1996 |
| Interfit Kitchens Limited | Construction | 2019 |
| Interhaze Limited | Health & social care | 1994 |
| Interim Goals Limited | Professional & scientific | 2013 |
| Interior Perfection ( Midlands ) Limited | Wholesale & retail | 2011 |
| Interior Ways Limited | Wholesale & retail | 2017 |
| Internal Control Limited | Financial services | 2014 |
| International Electrical Services Ltd | Construction | 2023 |
| International Management and Consulting Ltd | Professional & scientific | 2018 |
| International Motors Limited | Professional & scientific | 1976 |
| International Stock Distributors Limited | Wholesale & retail | 1997 |
| International Trade Shows Link Limited | Administrative & support | 1997 |
| Interoperable Ltd | Information & communication | 2020 |
| Interscope Creative Ltd | Professional & scientific | 2026 |
| Intertain (Bars) II Limited | Hospitality | 2015 |
| Intertain (Bars) III Limited | Wholesale & retail | 2015 |
| Intertain (Bars) IV Limited | Wholesale & retail | 2015 |
| Intertain (Bars) Limited | Hospitality | 2009 |
| Intertain Limited | Arts & recreation | 2009 |
| Interwork Careers Limited | Administrative & support | 2017 |
| Intraedge Limited | Information & communication | 2018 |
| Intransit Networks Limited | Information & communication | 2026 |
| Intrflex Limited | Information & communication | 2019 |
| Intrinity Ltd | Professional & scientific | 2021 |
| Intro-Drive Ltd | Education | 2016 |
| Intruder Alarm Academy Ltd | Education | 2021 |
| Inturail Limited | Construction | 2022 |
| Inventive Software Ltd | Administrative & support | 2022 |
| Inventor-E Holdings Limited | Financial services | 2017 |
| Inventor-E Limited | Manufacturing | 2001 |
| Inveresk Estates Limited | Real estate | 1999 |
| Invest in Houses Holdings Limited | Financial services | 2021 |
| Invest in Houses Limited | Real estate | 2014 |
| Invest in Learning Limited | Education | 2012 |
| Invest RR Ltd | Real estate | 2022 |
| Investin Acton Limited | Real estate | 2024 |
| Investin Ashford Properties Limited | Real estate | 2013 |
| Investin Asset Management LLP | | 2012 |
| Investin Beeston Limited | Real estate | 2019 |
| Investin Brandon Limited | Real estate | 2014 |
| Investin Bristol Street Limited | Real estate | 2022 |
| Investin Capital Limited | Real estate | 2023 |
| Investin Finance Limited | Real estate | 2011 |
| Investin Globe House Limited | Real estate | 2021 |
| Investin Greenwich Properties Limited | Real estate | 2021 |
| Investin Management (Westminster) LLP | | 2013 |
| Investin Properties (Brandon) Limited | Real estate | 2011 |
| Investin Properties Bournville Limited | Real estate | 2011 |
| Investin Properties PLC | Real estate | 2011 |
| Investin Sheldon Falmouth Developments Limited | Real estate | 2018 |
| Investin Slindon Hotels Limited | Real estate | 2023 |
| Investin Slindon Residential Limited | Real estate | 2023 |
| Investin Snow Hill Limited | Real estate | 2013 |
| Investin Solihull Limited | Real estate | 2018 |