| Innswood Homes Limited | Real estate | 2016 |
| INS Catering Ltd | Hospitality | 2024 |
| INS Developments Ltd | Real estate | 2023 |
| Insaf UK Motors Ltd | Wholesale & retail | 2024 |
| Insider Threat Ltd | Professional & scientific | 2024 |
| Inspection Services (Nationwide) Limited | Professional & scientific | 2009 |
| Inspired Elements Limited | Manufacturing | 2012 |
| Inspired Learning Group (London) (3) Limited | Financial services | 2024 |
| Inspired Learning Group (London) (4) Limited | Financial services | 2024 |
| Inspired Learning Group (London) (5) Limited | Financial services | 2025 |
| Inspired Learning Group (London) Limited | Professional & scientific | 2019 |
| Inspired Learning Group (LONDON)(1) Limited | Financial services | 2022 |
| Inspired Learning Group (LONDON)(2) Limited | Financial services | 2022 |
| Inspired Learning Group (UK) Limited | Education | 1981 |
| Inspired Learning Group Camps Limited | Health & social care | 2024 |
| Insquintive Limited | Information & communication | 2015 |
| Instinctive Behaviour Ltd | Arts & recreation | 2020 |
| Institute of Jainology Limited | Education | 2008 |
| Insulation Point Limited | Wholesale & retail | 2021 |
| Insys Systems Limited | Information & communication | 2017 |
| Integer Intelligent & Green Ltd. | Administrative & support | 1998 |
| Intellect Civil & Construction Limited | Construction | 2012 |
| Intellectwise Limited | Information & communication | 2025 |
| Intelligent Property Solutions Limited | Real estate | 2018 |
| Intense Fire Protection Ltd | Administrative & support | 2020 |
| Inter-Splash Limited | Wholesale & retail | 1997 |
| Interdeco Ltd | Construction | 2017 |
| Interface Industries Limited | Administrative & support | 1995 |
| Interiors Decore Limited | Construction | 2018 |
| International Alliance of Law Firms | Other services | 1997 |
| International Food Security Forum Limited | Administrative & support | 2023 |
| International Furniture Brands Limited | Wholesale & retail | 2007 |
| International Hospitality Holdings Ltd | Financial services | 2022 |
| International Leasing Partners Limited | Professional & scientific | 1998 |
| International London Management Ltd | Financial services | 2024 |
| Internet of Artists Ltd | Information & communication | 2015 |
| Interproperty Associates Limited | Real estate | 2013 |
| Into the Ether Limited | Information & communication | 2021 |
| Intoku Holdings Ltd | Hospitality | 2024 |
| Intraguard Limited | Professional & scientific | 2018 |
| Intraweb Solutions Limited | Administrative & support | 2003 |
| Investedge Limited | Information & communication | 2009 |
| Investments & Mortgages Ltd | Real estate | 2011 |
| Investments Global Limited | Financial services | 2006 |
| Investments Italia Ltd | Financial services | 2020 |
| Investwell Properties Ltd | Real estate | 2019 |
| Invitation London Limited | Information & communication | 2012 |
| IO Digital Limited | Information & communication | 2016 |
| Ioan Pintilie Ltd | Construction | 2014 |
| Iofero Ltd | Transport & logistics | 2026 |
| Ionelnico Limited | Transport & logistics | 2025 |
| Ionut & Luca (UK) Ltd | Construction | 2022 |
| Ionut Valu Haulage Ltd | Transport & logistics | 2021 |
| IOT Technology Limited | Information & communication | 2020 |
| IP Centrix Limited | Information & communication | 2009 |
| Ipdm. Ltd | Information & communication | 2022 |
| Ipharmpro Limited | Information & communication | 2012 |
| Ir.Pr Services Ltd | Administrative & support | 2025 |
| Irinel Trans Ltd | Transport & logistics | 2019 |
| IRO (UK) Limited | Wholesale & retail | 2013 |
| Iron Heart Studios Limited | Information & communication | 2012 |
| Isaac Pharma Limited | Manufacturing | 2022 |
| Ishanbi Limited | Wholesale & retail | 2021 |
| Ishkav Limited | Professional & scientific | 2024 |
| Ishya Solutions Limited | Information & communication | 2013 |
| Isik Ltd | Wholesale & retail | 2025 |
| Isoimages Limited | Professional & scientific | 2010 |
| Issey Consultancy Limited | Information & communication | 2010 |
| Isync AI Limited | Information & communication | 2020 |
| IT Skylight Limited | Information & communication | 2017 |
| It-Logix Ltd | Information & communication | 2007 |
| Italinvestments Holding Ltd | Financial services | 2020 |
| Itax Advisors Limited | Professional & scientific | 2019 |
| Itec Graphic Machinery Limited | Manufacturing | 2013 |
| Iten Fitness Ltd | Arts & recreation | 2025 |
| Ithaca Development Ltd | Professional & scientific | 2024 |
| Itinerant Works Limited | Information & communication | 2014 |
| ITM Automotive Consultancy Limited | Professional & scientific | 2021 |
| Itsmitul Ltd | Information & communication | 2026 |
| IV Near ME Ltd | Health & social care | 2019 |
| IVA Consulting Solutions Limited | Information & communication | 2024 |
| Iventure Online Limited | Professional & scientific | 2014 |
| IVG Services Limited | Manufacturing | 2015 |
| Ivneet Kaur Limited | Extraterritorial | 2018 |
| Ivory Indian Limited | Hospitality | 2018 |
| IVY Capital Limited | Construction | 2026 |
| IVY Cars Limited | Administrative & support | 2018 |
| IVY Chauffeur Drive Ltd | Transport & logistics | 2023 |
| Ivya Group Ltd | Construction | 2019 |
| Izeus Consultancy Limited | Other services | 2026 |
| J & J Law Limited | Professional & scientific | 2019 |
| J & L Jointing Ltd | Construction | 2026 |
| J & S Lyle Holdings Limited | Professional & scientific | 2011 |
| J a Legal Advisers Ltd | Professional & scientific | 2026 |
| J B Network Solutions Limited | Professional & scientific | 2006 |
| J Camps USA Limited | Extraterritorial | 2020 |
| J D Trading Limited | Real estate | 2009 |
| J G Builders (London) Limited | Construction | 2026 |
| J H Contract Services Limited | Construction | 2002 |
| J J Doshi Limited | Professional & scientific | 2011 |