| Infohub Digital Ltd | Information & communication | 2026 |
| Inform Media Publishing Ltd | Information & communication | 2020 |
| Infotech Consulting Limited | Professional & scientific | 2012 |
| Infra Safety Services Limited | Professional & scientific | 1998 |
| Infra SSR MRO Ltd | Transport & logistics | 2026 |
| Infracapital (Corelink) UK 1 Limited | Financial services | 2017 |
| Infracapital (Corelink) UK 2 Limited | Financial services | 2017 |
| Infracapital (Corelink) UK 3 Limited | Financial services | 2017 |
| Infracapital (Corelink) UK 4 Limited | Financial services | 2017 |
| Infralook Planning Services Ltd | Professional & scientific | 2024 |
| Infrastructure Measurement Solutions Ltd | Professional & scientific | 2008 |
| Infuse Security Limited | Information & communication | 2014 |
| Infuse Tech Limited | Information & communication | 2014 |
| Infuse Technology Limited | Information & communication | 2011 |
| Infusec Limited | Information & communication | 2022 |
| Inga Associates Limited | Hospitality | 2020 |
| Ingeniocity Limited | Professional & scientific | 2016 |
| Ingham & Holmes Ltd | Real estate | 2025 |
| Ingleby Investments (UK) Limited | Real estate | 2004 |
| Ingleby Living Limited | Real estate | 2018 |
| Ingleby Partners Limited | Real estate | 2019 |
| Inglenook Court (Derby) Management Company Limited | Real estate | 2004 |
| Ingrey Bespoke Sourcing Ltd | Real estate | 2026 |
| Ingrey Capital Ltd | Administrative & support | 2025 |
| Ingrey Lets Ltd | Real estate | 2018 |
| Injectaclad Ltd | Manufacturing | 2020 |
| INK Financial Management Limited | Financial services | 2004 |
| Inklusive C.I.C. | Manufacturing | 2011 |
| Inkshop Limited | Manufacturing | 2011 |
| Inna Heights Ltd | Administrative & support | 2024 |
| Inner City Revival Ltd | Construction | 2025 |
| Innerscape Media Ltd | Information & communication | 2025 |
| Inneva Group Limited | Professional & scientific | 2006 |
| Inneva Trustees Limited | Professional & scientific | 2015 |
| Inni Accounts Ltd | Professional & scientific | 2007 |
| Inni Ltd | Information & communication | 2004 |
| Innit Transport Ltd | Construction | 2019 |
| Innmeg Ltd | Information & communication | 2017 |
| Innocent Housing Agency Community Interest Company | Real estate | 2025 |
| Innotech Consultants Limited | Information & communication | 2023 |
| Innotech Solutions Ltd | Information & communication | 2026 |
| Innova Reactive Solutions Ltd | Administrative & support | 2024 |
| Innovace Designs Limited | Administrative & support | 2006 |
| Innovation Rewards Limited | Professional & scientific | 2019 |
| Innovative Engineering Ltd | Manufacturing | 2022 |
| Innovative Payment Solutions Ltd | Construction | 2025 |
| Innovative Support Solutions Ltd | Wholesale & retail | 2025 |
| Inodec Ltd | Construction | 2017 |
| Inovix Network Solutions Limited | Professional & scientific | 2014 |
| Insaaf Hajj & Umrah Ltd | Administrative & support | 2014 |
| Insane Fitness Ltd | Arts & recreation | 2020 |
| Insignia Properties Ltd | Real estate | 2025 |
| Insite Properties Ltd | Construction | 2025 |
| Insites Technologies Limited | Information & communication | 2021 |
| Insourcing Orthopaedics Ltd | Health & social care | 2026 |
| Inspirar Limited | Wholesale & retail | 2010 |
| Inspire & Enable Consulting Ltd | Professional & scientific | 2021 |
| Inspire Building Supplies Ltd | Other services | 2017 |
| Inspire Championship Boxing Limited | Arts & recreation | 2015 |
| Inspire Geniuses CIC | Education | 2021 |
| Inspire K9 Ltd | Other services | 2024 |
| Inspire Prototypes Ltd | Manufacturing | 2021 |
| Inspired Glass Ltd | Arts & recreation | 2011 |
| Inspired Plus Limited | Health & social care | 2020 |
| Inspired Quill | Information & communication | 2011 |
| Inspired Show Homes Limited | Construction | 2009 |
| Inspiring Wealth Ltd | Financial services | 2003 |
| Inspo Sport Limited | Arts & recreation | 2023 |
| Install Greener Solutions Ltd | Construction | 2023 |
| Instant Popup Shelters Ltd | Manufacturing | 2008 |
| Instant Valet Limited | Wholesale & retail | 2019 |
| Instauto Ltd | Wholesale & retail | 2024 |
| Insync Services (Nationwide) Ltd | Transport & logistics | 2019 |
| Intau Limited | Professional & scientific | 2009 |
| INTEGR8 Projects Ltd | Construction | 2020 |
| Integral MEP Limited | Construction | 2017 |
| Integral Wellbeing & Safety Consultancy Ltd | Professional & scientific | 2026 |
| Integral-Dent Ltd | Health & social care | 2016 |
| Integrated Program Solutions Ltd | Professional & scientific | 2017 |
| Integrated Web Solutions Ltd | Information & communication | 2021 |
| Integrity Chauffeurs Limited | Transport & logistics | 2024 |
| Integrity Handling Limited | Wholesale & retail | 2003 |
| Integrity Jersey Limited | Financial services | 2019 |
| Integrity Spine Care Limited | Health & social care | 2021 |
| Integrity Technical Services Limited | Construction | 2014 |
| Integrity Wealth Limited | Wholesale & retail | 2019 |
| Intellect Insight Consultants Ltd | Professional & scientific | 2024 |
| Intelligent Distributed Controls Limited | Information & communication | 2002 |
| Intense Rehab Medical Limited | Health & social care | 2025 |
| Inter-County Paramedic Ltd | Other services | 2005 |
| Intercity Railfreight Limited | Transport & logistics | 2015 |
| Interior Options (Derby) Limited | Wholesale & retail | 2003 |
| Interlude in Prague Limited | Information & communication | 2015 |
| International Auto Limited | Wholesale & retail | 2026 |
| International Bio-Consultancy Limited | Water & waste | 1996 |
| International Conference and Administrative Services for Health Ltd | Administrative & support | 2024 |
| International Electric Company Limited | Professional & scientific | 1999 |
| International Fruits Limited | Wholesale & retail | 2018 |
| International Mission Christian Centre | Other services | 2011 |
| International Protection Dogs Ltd | Other services | 2026 |