| IMO Investment Holdings Ltd | Financial services | 2022 |
| IMO Investments Ltd | Professional & scientific | 2022 |
| IMO Management Limited | Professional & scientific | 1991 |
| Impact 17+1 Club Limited | Education | 2019 |
| Impactful Care Limited | Administrative & support | 2025 |
| Imperial Nest Makers Limited | Real estate | 2018 |
| Imperium Electrical Ltd | Construction | 2023 |
| Inclusive Asset Management Ltd | Real estate | 2019 |
| Inclusive FM Limited | Administrative & support | 2014 |
| Indigo FS Ltd | Professional & scientific | 2025 |
| Individo Ltd | Construction | 2022 |
| Inertially Ltd | Information & communication | 2019 |
| Infermata Limited | Information & communication | 2017 |
| Infinite Direction Limited | Arts & recreation | 2012 |
| Infinite Opportunities Academy Limited | Education | 2024 |
| Infinitus Partners Limited | Professional & scientific | 2017 |
| Infinity Construct Ltd | Manufacturing | 2016 |
| Infinity Property Investment Group Limited | Construction | 2020 |
| Infinity Valeting 2 Ltd Ltd | Administrative & support | 2021 |
| Infintree Limited | Wholesale & retail | 2026 |
| Infoline Consultancy Limited | Information & communication | 2011 |
| Infornics Solutions Ltd | Information & communication | 2025 |
| Infrastructure Project Development Ltd | Professional & scientific | 1996 |
| Infused Pawfection Limited | Wholesale & retail | 2022 |
| Ingenious Video Limited | Administrative & support | 2015 |
| INH Services Ltd | Wholesale & retail | 2023 |
| Inhub Services Ltd | Wholesale & retail | 2025 |
| Inna Transport Ltd | Transport & logistics | 2024 |
| Inrail Solutions Limited | Construction | 2017 |
| Insight Data Analytics Limited | Information & communication | 2018 |
| Insight Vision Ltd | Information & communication | 2024 |
| Instaresource Ltd | Administrative & support | 2023 |
| Integraiq Holdings Limited | Financial services | 2021 |
| Integraiq Limited | Construction | 2018 |
| Integral Global Ltd | Information & communication | 2015 |
| Intelligent Fabric Technologies Holdings Limited | Manufacturing | 2016 |
| Intelligent Fabric Technologies Limited | Manufacturing | 2001 |
| Intense Velocity Group Limited | Information & communication | 2017 |
| Interface Holdings Limited | Financial services | 2020 |
| Interhome Construction Ltd | Construction | 2025 |
| Interstaff Services Ltd | Administrative & support | 2019 |
| Intimate Health by Kate Waters Limited | Health & social care | 2025 |
| Intrad Architectural Systems Limited | Administrative & support | 1999 |
| Invecotech Limited | Information & communication | 2021 |
| Investmanage Limited | Professional & scientific | 2006 |
| Investments at Number 23 Limited | Extraterritorial | 2023 |
| Invicta Automobiles Limited | Wholesale & retail | 1994 |
| Invicta Motors (Maidstone) Limited | Wholesale & retail | 2010 |
| Invicta Motors Limited | Wholesale & retail | 1922 |
| Invisible Inc Creative Limited | Professional & scientific | 2008 |
| IO Entertainment Ltd | Information & communication | 2023 |
| Ionut Solutions Ltd | Transport & logistics | 2024 |
| Ippocrates Medical Consultancy Ltd | Real estate | 2015 |
| Iraco Real Estate Limited | Real estate | 2011 |
| Iron Arrow Investments Ltd | Financial services | 2026 |
| Iron Hand Film Lighting Limited | Administrative & support | 2021 |
| Iron Hills Group Limited | Professional & scientific | 2024 |
| Irvin Point Management Company Limited | Households | 1968 |
| IS Property Consultants Ltd | Real estate | 2023 |
| Isawan Thai Massage Limited | Other services | 2024 |
| Ispeakforyou Limited | Professional & scientific | 2024 |
| Isuzu Truck (UK) Limited | Wholesale & retail | 2003 |
| Isyoma Limited | Health & social care | 2019 |
| Ital Living Ltd | Wholesale & retail | 2012 |
| Italia Stone Ltd | Manufacturing | 2007 |
| Italy Roncott Co., Ltd | Mining & quarrying | 2025 |
| Itan London Limited | Wholesale & retail | 2026 |
| Itisat Solutions Ltd | Professional & scientific | 2012 |
| Itoma Ltd. | Manufacturing | 2017 |
| Ivan Services Ltd | Health & social care | 2015 |
| Ivan Trans Ltd | Transport & logistics | 2021 |
| Ivor Court Freehold Limited | Households | 2011 |
| IVY Advisory Limited | Financial services | 2002 |
| IVY Hill Residential Management Company Limited | Households | 2022 |
| Iztrust Design Studio Ltd | Information & communication | 2025 |
| J a Moro Consulting Ltd | Health & social care | 2012 |
| J C Practice Managers Limited | Administrative & support | 2019 |
| J Day Electrical Limited | Construction | 2015 |
| J E P Surveying Ltd | Professional & scientific | 2011 |
| J Law Holding Limited | Professional & scientific | 2021 |
| J P Tailoring Limited | Wholesale & retail | 2014 |
| J Pearson Consulting Limited | Professional & scientific | 2016 |
| J&U Estates Ltd | Real estate | 2021 |
| J.Dorling Management Services Limited | Construction | 2013 |
| J.Huba Ltd | Construction | 2019 |
| J.L.R Rigging Ltd | Construction | 2025 |
| J.P.M. Haulage Limited | Transport & logistics | 2004 |
| J65 Ltd | Construction | 2026 |
| Jabo Properties Limited | Real estate | 2020 |
| Jack & PAT Shine Ltd | Information & communication | 2019 |
| Jack Bailey Built Ltd | Construction | 2026 |
| Jacobus Bean Consulting Ltd | Professional & scientific | 2019 |
| JAG Management Ltd | Real estate | 2022 |
| Jah'Srock Ltd | Administrative & support | 2026 |
| Jake M and Sons Limited | Wholesale & retail | 2011 |
| Jamag Ltd | Health & social care | 2023 |
| James ALI Transport Ltd | Transport & logistics | 2025 |
| James Taylor Design and Build Limited | Construction | 2018 |
| James Taylor Development Management Limited | Construction | 2023 |
| James Taylor Developments Limited | Extraterritorial | 2011 |