| IM First Limited | Health & social care | 2026 |
| Imadene Gardens Ltd | Other services | 2017 |
| Imaeco Projects Limited | Professional & scientific | 2026 |
| Image Cars Limited | Wholesale & retail | 2015 |
| Image Cars Swindon Ltd | Wholesale & retail | 2024 |
| Image Cars Transportation (ICT) Ltd | Transport & logistics | 2025 |
| Image Interiors and Developments Limited | Real estate | 2018 |
| Image Plastering & Drylining Limited | Construction | 2014 |
| Image Property Developments Limited | Real estate | 2020 |
| Image Styles (Swindon) Limited | Construction | 2002 |
| Imagination Childcare Ltd | Administrative & support | 2015 |
| Imagination Photography Limited | Arts & recreation | 2017 |
| Imagine Media Ltd. | Professional & scientific | 2013 |
| Imaniharry's Care Ltd | Health & social care | 2023 |
| Imersia Ltd | Education | 2025 |
| Immediate Care & Support UK Limited | Health & social care | 2013 |
| IMMIGRATION4UK Limited | Professional & scientific | 2004 |
| Immobilarium Ltd | Real estate | 2020 |
| Immovation Limited | Professional & scientific | 2002 |
| Immz Limited | Real estate | 2024 |
| Immz Solutions Limited | Professional & scientific | 2026 |
| Immz Trader Limited | Wholesale & retail | 2026 |
| Imnet Limited | Administrative & support | 2016 |
| Impact Bricklaying Ltd | Construction | 2020 |
| Impact Horizon Limited | Extraterritorial | 2023 |
| Impact Land Promotion Limited | Professional & scientific | 2013 |
| Impact Planning Services Ltd | Professional & scientific | 2005 |
| Impartic Limited | Information & communication | 2001 |
| Impeckable Cleaning Ltd | Administrative & support | 2023 |
| Imperial Facilities Solutions Ltd | Wholesale & retail | 2019 |
| Imperial Importers Limited | Wholesale & retail | 2024 |
| Imperial Logistics International (UK) Limited | Transport & logistics | 2002 |
| Imperial Property Solutions (Swindon) Ltd | Real estate | 2017 |
| Imperial Tech Companies Limited | Manufacturing | 2020 |
| Imperial Tyres Limited | Wholesale & retail | 1975 |
| Implantar Ltd | Manufacturing | 2020 |
| Impleo Professional Services Limited | Information & communication | 2007 |
| Improbable Books Limited | Arts & recreation | 2026 |
| Improve International Ltd. | Education | 1998 |
| IN Good Company (UK) Ltd | Professional & scientific | 2011 |
| In-House Research Limited | Professional & scientific | 1998 |
| Inara Holdings (UK) Ltd | Financial services | 2025 |
| Incent Ltd | Information & communication | 2023 |
| Incentive Studio Limited | Information & communication | 2006 |
| Inception Business Technology Limited | Administrative & support | 2004 |
| Incorporated British and Foreign Bible Society Association (the) | Extraterritorial | 1907 |
| Indbroks Ltd | Financial services | 2025 |
| Independence Works Limited | Health & social care | 2013 |
| Independent Business Resource Limited | Administrative & support | 2003 |
| Independent GAS (UK) Limited | Wholesale & retail | 2022 |
| Independent Integrity Inspection Limited | Professional & scientific | 2001 |
| Index Medical Services Limited | Information & communication | 2018 |
| India Bazzar (PVT) Ltd | Wholesale & retail | 2018 |
| Indie Beer Fridge Limited | Wholesale & retail | 2020 |
| Indie Properties Limited | Professional & scientific | 2019 |
| Indiecrew Limited | Other services | 2015 |
| Indietwist Ltd | Hospitality | 2025 |
| Indigo (Swindon) Limited | Construction | 2016 |
| Indigo Property Solutions Limited | Administrative & support | 2015 |
| Indipac Logistics Limited | Transport & logistics | 2013 |
| Individual Entertainment Limited | Arts & recreation | 2013 |
| Indtech Investments Limited | Financial services | 2019 |
| Indtech Limited | Wholesale & retail | 2013 |
| Indtech Properties Limited | Administrative & support | 2019 |
| Industrial Asset Services Limited | Administrative & support | 2016 |
| Industrial Electric Limited | Wholesale & retail | 2014 |
| Industrial Electronic Wiring Limited | Manufacturing | 1996 |
| Industrial Printer Services Limited | Manufacturing | 2012 |
| Industrial Printer Services NO.2 Limited | Manufacturing | 2021 |
| Indyland Limited | Hospitality | 2017 |
| Infinite 12 Ltd | Transport & logistics | 2025 |
| Infinite Group Holdings Limited | Financial services | 2015 |
| Infinite Group Limited | Professional & scientific | 2005 |
| Infinite Procurement Solutions Ltd | Professional & scientific | 2017 |
| Infinithoughts Consulting Ltd | Information & communication | 2017 |
| Infiniti Consultants Limited | Professional & scientific | 2024 |
| Infiniti Hair & Nails Limited | Other services | 2017 |
| Infinity CIS Ltd | Information & communication | 2017 |
| Infinity Control Solutions Ltd | Administrative & support | 2013 |
| Infinity Fit Ltd | Wholesale & retail | 2020 |
| Infinity Motors Ltd | Wholesale & retail | 2021 |
| Infinity Nation Ltd | Information & communication | 2007 |
| Infinity Shore Limited | Construction | 2024 |
| Infinity Square Development Limited | Construction | 2019 |
| Infinity Square Investments Limited | Real estate | 2019 |
| Infitech Ltd | Information & communication | 2019 |
| Infix Ltd | Wholesale & retail | 2024 |
| Influence Sales Limited | Professional & scientific | 2011 |
| Inform PA Limited | Administrative & support | 2020 |
| Information Systems Examinations Board Limited | Education | 1990 |
| Informed Safeguarding Ltd | Education | 2025 |
| Infovate Consulting Ltd | Information & communication | 2026 |
| INFRA3 Limited | Professional & scientific | 2017 |
| Infratec Resource Solutions Limited | Administrative & support | 2024 |
| Inga Financial Limited | Administrative & support | 2017 |
| Ingenious (Events & Consultancy) Ltd | Professional & scientific | 2021 |
| Ingram International Ltd | Information & communication | 2022 |
| Inhabitus Developments Limited | Administrative & support | 2025 |
| Inhabitus Limited | Administrative & support | 2024 |
| Inhouse Hospitality Limited | Hospitality | 2016 |