| Imperial Care Group 3 Ltd | Financial services | 2024 |
| Imperial Care Group 4 Ltd | Financial services | 2025 |
| Imperial Care Group 5 Ltd | Financial services | 2025 |
| Imperial Care Group Ltd | Financial services | 2019 |
| Imperial Sandringham Group Limited | Professional & scientific | 2021 |
| Imperium Estates South East Limited | Real estate | 2024 |
| Implementationworks Ltd | Administrative & support | 2023 |
| Imposing Image Ltd | Information & communication | 2019 |
| Imprimi PS LLP | | 2013 |
| IMT Advisory Ltd | Professional & scientific | 2024 |
| IN Other Words Editing Ltd | Professional & scientific | 2023 |
| IN the A.M. Patisserie Ltd | Hospitality | 2025 |
| IN the Wild Music Limited | Information & communication | 2024 |
| In-Crease Finishers Limited | Manufacturing | 2006 |
| INCAHOOTS3D Limited | Wholesale & retail | 2025 |
| Incentivise for Growth U.K. Limited | Administrative & support | 2000 |
| Inck-D Ltd | Information & communication | 2010 |
| Incus Group Ltd | Households | 2024 |
| Independent Adult Social Work (Hove) Ltd | Health & social care | 2019 |
| Independent Scaffolding Brighton Limited | Construction | 2008 |
| Independent Social Work Matters Ltd | Health & social care | 2007 |
| India Moon Ltd | Professional & scientific | 2021 |
| Indigo Diagnostics Limited | Professional & scientific | 2016 |
| Indigo EYE Productions Ltd | Other services | 2017 |
| Indigo Leisure Investments Limited | Financial services | 2012 |
| Indigo Leisure Limited | Hospitality | 1999 |
| Indigo Talent Limited | Administrative & support | 2007 |
| Indigo Vesta Ltd | Professional & scientific | 2021 |
| Indigodent Education Limited | Health & social care | 2020 |
| Indo-Celtic Holdings Limited | Construction | 2019 |
| Indo-Celtic Limited | Construction | 2012 |
| Industrial Control and Communication Ltd. | Information & communication | 1995 |
| Ines Immobiliare Limited | Extraterritorial | 2009 |
| INF Dental Limited | Health & social care | 2020 |
| Infield MS LLP | | 2012 |
| Infinite Cloud IT Ltd | Information & communication | 2024 |
| Infiniti Holdco Ltd | Financial services | 2013 |
| Infinity Engineering Ltd | Professional & scientific | 2011 |
| Infinity Surveying Ltd | Construction | 2012 |
| Infraconsult Digital Limited | Professional & scientific | 2024 |
| Infraconsult Holdings Limited | Administrative & support | 2014 |
| Infraconsult Investment Management Limited | Professional & scientific | 2022 |
| Infraconsult Limited | Professional & scientific | 2012 |
| Infraconsult Management Services Limited | Professional & scientific | 2012 |
| Infraconsult Technical Services Ltd | Professional & scientific | 2022 |
| Infuse LAB Limited | Information & communication | 2013 |
| Ingham Jones Limited | Administrative & support | 2020 |
| Inkpin Decor Ltd | Construction | 2024 |
| Inky Press Ltd | Information & communication | 2001 |
| Inmo Ltd | Other services | 2006 |
| Innately Ltd | Professional & scientific | 2011 |
| Inner Healing World Ltd | Information & communication | 2024 |
| Inner-City Contracts Ltd | Administrative & support | 2011 |
| Innervaters Ltd | Administrative & support | 2018 |
| Innit Townhouse Limited | Real estate | 2023 |
| Innodata Limited | Information & communication | 2024 |
| Innovarex MS Limited | Wholesale & retail | 2024 |
| INNOVAT8 LAB Ltd | Professional & scientific | 2019 |
| Innovative Hair Beauty Ltd | Other services | 2024 |
| Inovris Ltd | Professional & scientific | 2026 |
| Inpeco Ltd | Information & communication | 2021 |
| Insa-Build Ltd | Construction | 2026 |
| Insa-Rend Ltd | Construction | 2011 |
| Inspired Collective Services Limited | Hospitality | 2025 |
| Inspired Motorhome Hire Limited | Administrative & support | 2020 |
| Instasolve Ltd | Wholesale & retail | 2024 |
| Instrive Limited | Professional & scientific | 2019 |
| Insure IT Direct Holdings Ltd | Financial services | 2017 |
| Insure IT Direct Ltd | Financial services | 2017 |
| Insure IT Holdings Ltd | Financial services | 2017 |
| Insuresat Ltd | Extraterritorial | 2008 |
| Integral Building & Decorating Ltd | Construction | 2019 |
| Integrated FM Solutions Limited | Construction | 2013 |
| Integrative Health Ltd | Health & social care | 2017 |
| Integrity Executive Coaching Limited | Professional & scientific | 2014 |
| Integrity Research Ltd | Professional & scientific | 2016 |
| Intel SRM Ltd | Financial services | 2024 |
| Intellexi Project Management Limited | Construction | 2023 |
| Intelligendo Ltd | Health & social care | 2010 |
| Intelligent Publishing Applications Limited | Information & communication | 2023 |
| Intelligent Travel Solutions Limited | Professional & scientific | 2016 |
| Intellitrade Investment Co., Ltd. | Manufacturing | 2019 |
| Intelva Ltd | Information & communication | 2020 |
| Intenso Cafe Limited | Hospitality | 2006 |
| Inter Connect Investments Ltd | Administrative & support | 2022 |
| Intercamps Ltd | Education | 2023 |
| Intercane Limited | Transport & logistics | 1988 |
| Interchange Films Limited | Other services | 1976 |
| Interia Design Ltd | Professional & scientific | 2022 |
| Interim Sales Consultants Ltd | Wholesale & retail | 2012 |
| International Independent Assure Limited | Real estate | 2017 |
| International Legal Mediation Centre Ltd | Professional & scientific | 2023 |
| International Responsible Leadership Ltd | Education | 2025 |
| International Technology Group Limited | Professional & scientific | 1993 |
| Interuni Limited | Real estate | 2003 |
| Intheflow Ltd | Wholesale & retail | 2022 |
| Intramek Limited | Professional & scientific | 2014 |
| Intrinsic Books Limited | Wholesale & retail | 2010 |
| Intro Protect Limited | Professional & scientific | 2015 |
| Intrusion Limited | Financial services | 2023 |