| ICT Hero Limited | Information & communication | 2008 |
| ID Trans Ltd | Transport & logistics | 2020 |
| Ideal Cleaning, Airbnb Management Ltd | Administrative & support | 2025 |
| Idyllic Pubs Ltd | Hospitality | 2023 |
| Idyllic Retreats Limited | Hospitality | 2022 |
| Iglaze Aluminium Limited | Manufacturing | 2016 |
| Igoe Tradings Limited | Information & communication | 2017 |
| IGX Capital UK, Ltd. | Wholesale & retail | 2016 |
| ILE Afrik Limited | Hospitality | 2018 |
| Ilektra Limited | Financial services | 2022 |
| Illuminate Events Ltd | Other services | 2013 |
| Imaging Ltd | Health & social care | 2021 |
| Imec Care Limited | Health & social care | 2022 |
| Imec Consult Ltd | Professional & scientific | 2023 |
| Immy Davis Limited | Administrative & support | 2023 |
| Imocat Limited | Professional & scientific | 2015 |
| Imogen Distribution Limited | Administrative & support | 2014 |
| IMP Studio & Live Limited | Professional & scientific | 2019 |
| Imperium Dwellings Ltd | Real estate | 2020 |
| Imperium Engineering Ltd | Construction | 2017 |
| Imperium Engineering Services Ltd | Construction | 2023 |
| Imperium Enterprises Ltd | Financial services | 2024 |
| Imperium Fuels Ltd | Wholesale & retail | 2025 |
| Imperium Property Advisory Ltd | Real estate | 2025 |
| Imperium Property Leases Kent Ltd | Real estate | 2025 |
| Imperium Property Leases Ltd | Real estate | 2025 |
| Imperium Property Maintenance Ltd | Construction | 2024 |
| Imperium Trading International Ltd | Wholesale & retail | 2025 |
| Impress Promotions Ltd | Wholesale & retail | 2014 |
| IN Conversation Limited | Professional & scientific | 2011 |
| IN the Moment Productions Limited | Information & communication | 2010 |
| IN the Night Sky Limited | Information & communication | 2024 |
| Inca Engineering Limited | Professional & scientific | 2023 |
| Incedo Culture Limited | Professional & scientific | 2020 |
| Incepta Ltd | Information & communication | 2023 |
| Incorporated Church Institute,Upper Tooting(The) | Other services | 1891 |
| Indigo Assets Ltd | Real estate | 2021 |
| Indraminimart Ltd | Wholesale & retail | 2025 |
| Infinite Oasis Healthcare Ltd | Health & social care | 2023 |
| Infinity Kent Ltd | Wholesale & retail | 2022 |
| Ingenium Biometric Laboratories Limited | Information & communication | 2019 |
| Inizio TRE Ltd | Professional & scientific | 2025 |
| Inner Soul Revolution Ltd | Other services | 2023 |
| Inovaspire Limited | Administrative & support | 2001 |
| Inphase Communications Limited | Information & communication | 1995 |
| Inprojex Automotive Limited | Professional & scientific | 2002 |
| Inramen UK Ltd | Hospitality | 2019 |
| Insconic Ltd | Extraterritorial | 2017 |
| Insight Screening Limited | Administrative & support | 2025 |
| Insightful Healthy Lifestyle Solutions C.I.C. | Health & social care | 2011 |
| Inspire Contract Services Group Limited | Construction | 2026 |
| Inspire Contract Services Holdings Limited | Financial services | 2023 |
| Inspire Contract Services Limited | Construction | 2014 |
| Inspired Assets Ltd | Real estate | 2013 |
| Inspired Canterbury Ltd | Professional & scientific | 1995 |
| Inspired Music Ltd. | Arts & recreation | 2015 |
| Inspired Property Ltd. | Real estate | 2014 |
| Inspired Technology Services Limited | Information & communication | 2002 |
| Inspirit Investments Limited | Other services | 2023 |
| Instaconnect Limited | Information & communication | 2023 |
| Institute for Children, Youth and Mission | Education | 2000 |
| Institute of Heraldic and Genealogical Studies(The) | Professional & scientific | 1982 |
| Instrument Tutor Ltd | Other services | 2016 |
| Instrumental Limited | Arts & recreation | 2004 |
| Integral Brickwork Ltd | Construction | 2026 |
| Integrate Economics Ltd | Professional & scientific | 2025 |
| Integrated Medical Services Management Limited | Health & social care | 2019 |
| Integrity Control Systems Ltd | Administrative & support | 2011 |
| Intelligent Business Group Limited | Information & communication | 2018 |
| Intenco Ltd | Wholesale & retail | 2021 |
| Interactive Logistic Solutions Ltd. | Information & communication | 2016 |
| Interactive Media Investor LLP | | 2005 |
| International Alliance of Dietary/Food Supplement Associations (Iadsa) Ltd | Other services | 2014 |
| International Association of Language Centres Limited | Other services | 2014 |
| International Creative Industries Group Limited | Wholesale & retail | 2019 |
| Into the NOW CIC | Education | 2023 |
| Invenimus UK Ltd | Manufacturing | 2025 |
| Invicta Bass Limited | Administrative & support | 2025 |
| Invicta Catering Equipment Limited | Construction | 1995 |
| Invicta Catering Repair Ltd | Construction | 2004 |
| Invicta Commercials Ltd | Wholesale & retail | 2020 |
| Invicta Group Limited | Professional & scientific | 2015 |
| Invicta Health Community Interest Company | Health & social care | 2008 |
| Invicta IT Solutions Limited | Information & communication | 2005 |
| Invicta Land Limited | Real estate | 1999 |
| Invicta Metal Services Ltd | Water & waste | 2016 |
| Invicta Planning Ltd | Professional & scientific | 2019 |
| Invicta Produce Limited | Wholesale & retail | 2015 |
| Invicta Ratio London Limited | Financial services | 2012 |
| Invicta Stone Ltd | Construction | 2025 |
| Invicta Tools & Fixings Limited | Wholesale & retail | 1996 |
| Invicta Tweed Ltd | Manufacturing | 2022 |
| Invicta Tyres Ltd | Wholesale & retail | 2023 |
| Invicta Ventures Group Ltd | Financial services | 2025 |
| Inway Investments Limited | Real estate | 2000 |
| Inyougo Group Limited | Information & communication | 2025 |
| Ioassn Ltd | Other services | 2024 |
| Ioncube Limited | Information & communication | 2002 |
| Iorigins Ltd | Information & communication | 2021 |
| IOT Cloud Controls Ltd | Manufacturing | 2024 |