| I Love Coffee Ltd | Hospitality | 2024 |
| I&G Electric Ltd | Construction | 2026 |
| I.J. Parkash (U.K.) Limited | Extraterritorial | 1985 |
| I.J.Parkash Limited | Wholesale & retail | 1963 |
| I4C Services Ltd | Administrative & support | 2025 |
| IA Pharma Limited | Health & social care | 2019 |
| Iain Campbell Garden Maintenance Limited | Other services | 2002 |
| Iali Pharm Ltd | Wholesale & retail | 2023 |
| Iasecurity Limited | Information & communication | 2008 |
| Iaspire Healthcare Ltd | Health & social care | 2016 |
| IB Construction Gatley Ltd | Construction | 2019 |
| Ibra Care Ltd | Wholesale & retail | 2023 |
| Ibrahim Shah Ltd | Wholesale & retail | 2025 |
| Ibrayan Limited | Hospitality | 2025 |
| Ibreez Trading Ltd | Construction | 2024 |
| Ibrews Ltd | Professional & scientific | 2015 |
| Ice Manchester Ltd. | Wholesale & retail | 2018 |
| Iconic Design and Build Limited | Construction | 2019 |
| Iconic Financial Limited | Professional & scientific | 2025 |
| ICT Technology Limited | Information & communication | 2026 |
| Ideactory Limited | Information & communication | 2024 |
| Ideal Heating Ltd | Manufacturing | 2019 |
| Ideas to Prototype Limited | Professional & scientific | 2024 |
| IFA Sports Limited | Other services | 2019 |
| Igloo Finance Ltd | Financial services | 2012 |
| IH Pharm Ltd | Wholesale & retail | 2024 |
| Iionme Ltd | Manufacturing | 2020 |
| Ijaz Surgery Limited | Health & social care | 2014 |
| IJN Ltd | Wholesale & retail | 2025 |
| IJP Wealth Management Limited | Financial services | 2012 |
| Ikyy Ltd | Real estate | 2025 |
| Illicit Attire Limited | Extraterritorial | 2023 |
| IM Health Limited | Health & social care | 2023 |
| Images of Light UK Limited | Professional & scientific | 2003 |
| IMAGING786 Services Ltd | Health & social care | 2019 |
| Imani Clothing Limited | Wholesale & retail | 2001 |
| Imani London Limited | Wholesale & retail | 2010 |
| Imas Medical Ltd | Professional & scientific | 2024 |
| Imas Medical Services Ltd | Health & social care | 2015 |
| Imba Dynamics Ltd | Information & communication | 2024 |
| Imet Trade UK Co Limited | Hospitality | 2012 |
| Immersed Films Ltd | Information & communication | 2026 |
| Implantsbyam Limited | Health & social care | 2014 |
| Implicit Wealth Ltd | Financial services | 2012 |
| Impresa Medica Ltd | Health & social care | 2016 |
| Improbus Consultancy Limited | Professional & scientific | 2023 |
| Imran Nawaz Consulting Ltd | Professional & scientific | 2022 |
| Imtech Hub Ltd | Information & communication | 2025 |
| IMW Property Limited | Real estate | 2025 |
| IN Dose Ltd | Wholesale & retail | 2026 |
| IN Real Estate Ltd | Real estate | 2024 |
| IN Shape Clinic Limited | Health & social care | 2024 |
| IN Vino Bidco Limited | Wholesale & retail | 2013 |
| IN Vino Limited | Wholesale & retail | 2013 |
| IN Vino Property Limited | Real estate | 2014 |
| IN2LETTINGS Ltd | Real estate | 2017 |
| IN2MORTGAGES Ltd | Financial services | 2021 |
| Index Investment Management Limited | Real estate | 2003 |
| Indie Property Investments Limited | Real estate | 2025 |
| Indo Spice UK Ltd | Hospitality | 2022 |
| Inducom Ltd | Manufacturing | 2021 |
| Ineffable Property Ltd | Real estate | 2023 |
| Infatrade (UK) Ltd. | Professional & scientific | 1993 |
| Infatrade Property Ltd | Real estate | 2016 |
| Inforail Ltd | Construction | 2017 |
| Ingle Control Systems Limited | Professional & scientific | 1998 |
| INK Code Ltd | Wholesale & retail | 2020 |
| Innovate Technology Limited | Information & communication | 2017 |
| Innovo Cladding Services Limited | Construction | 2023 |
| Innproved Ltd | Hospitality | 2018 |
| Innventigo Limited | Health & social care | 2015 |
| Inova Parts Ltd | Wholesale & retail | 2023 |
| Insider Pathways CIC | Health & social care | 2025 |
| Insight Joinery Ltd | Construction | 2025 |
| Insitugen (UK) Limited | Manufacturing | 2023 |
| Insolvency Investigations Ltd | Other services | 2012 |
| Inspire Building Developments Ltd | Construction | 2018 |
| Inspire Capital Limited | Professional & scientific | 2015 |
| Inspire Capital Propco Limited | Real estate | 2021 |
| Inspire Capital Sports CIC | Arts & recreation | 2023 |
| Inspire Renovations NW Limited | Construction | 2021 |
| Inspired Cheshire Limited | Real estate | 2016 |
| Inspired Fabrick Ltd | Real estate | 2017 |
| Inspired Recruitment Limited | Administrative & support | 2000 |
| Inspiring Individuals Ltd | Education | 2024 |
| Inspiring Your Success Limited | Professional & scientific | 2010 |
| Instruct Construction Group Ltd | Construction | 2025 |
| Inta Limited | Administrative & support | 2016 |
| Intazone Limited | Information & communication | 2000 |
| Integra Cladding Limited | Construction | 2022 |
| Integral Design Developments Ltd | Construction | 2020 |
| Integral Trades Ltd | Construction | 2024 |
| Integrate Hearing Ltd | Wholesale & retail | 2018 |
| Integrated Compound Semiconductors Limited | Manufacturing | 1994 |
| Intelligent Energies Limited | Administrative & support | 2011 |
| Intelligent Finance Limited | Professional & scientific | 2017 |
| Intelligent Property Training Ltd | Education | 2026 |
| Intellisus Ltd | Administrative & support | 2024 |
| Inter City Logistics Limited | Transport & logistics | 2004 |
| Inter Polymer Limited | Water & waste | 2016 |