| IBK Healthcare Ltd | Health & social care | 2015 |
| Ibrahim Clothing Holdings Ltd | Wholesale & retail | 2026 |
| Ican Software Limited | Information & communication | 1996 |
| Icarus Estates Limited | Wholesale & retail | 2023 |
| Icarus Technology Ltd | Professional & scientific | 1998 |
| Icon Design Studio Ltd | Professional & scientific | 2012 |
| Icon Train Smarter Ltd | Information & communication | 2025 |
| ID Data Management Limited | Information & communication | 2007 |
| Id.Com Limited | Extraterritorial | 2005 |
| IDA Beauty Ltd | Wholesale & retail | 2020 |
| Ideal Supermarket 2014 Limited | Wholesale & retail | 2023 |
| Idrivemedway Limited | Education | 2024 |
| Ifekate Properties Ltd | Real estate | 2020 |
| Iftikhar Consultants Ltd | Health & social care | 2015 |
| Ignatius Health Ltd | Administrative & support | 2023 |
| Igonipulo Limited | Public administration | 2020 |
| Igortransport Limited | Transport & logistics | 2016 |
| IGP Venture Limited | Information & communication | 2026 |
| Ijak, I'M Just a KID Limited | Wholesale & retail | 2021 |
| IJS Data Consulting Limited | Information & communication | 2025 |
| Ikoyi Suya & Grill Ltd | Hospitality | 2023 |
| Ileea Construction Limited | Construction | 2023 |
| Illumina Services Ltd | Professional & scientific | 2012 |
| Ilynor Brighton Ltd | Hospitality | 2026 |
| Ilynor Newcastle Ltd | Hospitality | 2024 |
| Imirzan Properties Ltd | Real estate | 2024 |
| Immaculate Communication Consulting Limited | Information & communication | 2025 |
| Immaculate Communication Limited | Real estate | 2013 |
| Impact HR Services Limited | Administrative & support | 2009 |
| Impact Zone Ltd | Arts & recreation | 2026 |
| Impart Global Consultancy Training & Recruitment Services Ltd | Professional & scientific | 2013 |
| Imperial Enterprise Ltd | Professional & scientific | 2020 |
| Imperial Global Ventures Limited | Wholesale & retail | 2013 |
| Impossible IS Nothing Global Solutions Ltd | Hospitality | 2022 |
| Imts Grinding Technology Ltd. | Manufacturing | 1990 |
| Inanlis Ltd | Transport & logistics | 2025 |
| Inchoi Safety UK Ltd | Extraterritorial | 2021 |
| Independent Commissioning Engineer & Design Limited | Construction | 2012 |
| Independent Conciliation Limited | Professional & scientific | 2003 |
| Independent Vision (Mere) Ltd | Administrative & support | 2010 |
| Industrial & Heritage Boiler Makers Ltd | Manufacturing | 2025 |
| Infinity IT Solutions Ltd | Information & communication | 2025 |
| Infinity Life Skills CIC | Health & social care | 2014 |
| Infinlix Ltd | Professional & scientific | 2022 |
| Influential Consultants Limited | Real estate | 1997 |
| Info Techo Limited | Wholesale & retail | 2025 |
| Ingleton Contract Services Limited | Construction | 2020 |
| Ingredients Matter Limited | Professional & scientific | 2014 |
| Initial Care Services South East Ltd Limited | Health & social care | 2017 |
| Inland Diamond Products Co., Ltd | Manufacturing | 2019 |
| Inn Business Pubs (Catford) Ltd | Hospitality | 2018 |
| Inn on the Lake Limited | Hospitality | 1990 |
| Inn-Tention Taverns Ltd | Hospitality | 2020 |
| Innerhealth Limited | Health & social care | 2026 |
| Innovaite Ltd | Professional & scientific | 2025 |
| Innovate to Illuminate Limited | Manufacturing | 2016 |
| Innovation Vehicle Bodyrepairs Ltd | Wholesale & retail | 2017 |
| Innovative Sales and Marketing Limited | Manufacturing | 2021 |
| Innspiire Solutions UK Ltd | Other services | 2021 |
| Inplace Interiors Ltd | Transport & logistics | 2017 |
| Insight Optical Training Limited | Education | 2017 |
| Inspector GAS Limited | Construction | 2014 |
| Inspiratus Training Ltd | Education | 2012 |
| Inspire Support and Consultancy Services Limited | Health & social care | 2016 |
| Instrument & Control Engineering Service Ltd | Professional & scientific | 2024 |
| Intec Services Limited | Construction | 2008 |
| Integrated Biomedical Laboratories Limited | Professional & scientific | 2014 |
| Integrity Building Specialists Limited | Construction | 2025 |
| Integrity Lift Compliance Ltd | Professional & scientific | 2026 |
| Intelligent Vehicle Diagnostics Ltd | Wholesale & retail | 2023 |
| Internal Vision Solutions Limited | Construction | 2024 |
| International Education Solutions Ltd | Education | 2017 |
| International Education Solutions Products Ltd | Education | 2018 |
| Intricate Photography Ltd | Professional & scientific | 2025 |
| Intrinsic Development Corporation (UK) Limited | Information & communication | 2003 |
| Intuitus Ltd | Information & communication | 2025 |
| Invasion Creator Network Ltd | Professional & scientific | 2026 |
| Invicta Air Conditioning Ltd | Construction | 2025 |
| Invicta Carpentry & Construction Ltd | Manufacturing | 2019 |
| Invicta Legal Services Ltd | Administrative & support | 2012 |
| Invicta Medieval Combat Ltd | Arts & recreation | 2025 |
| Invictus Jiu-Jitsu Ltd | Arts & recreation | 2024 |
| Invictus Sports Group (Kent) Limited | Arts & recreation | 2021 |
| Inzinctive Interiors Ltd | Manufacturing | 2025 |
| IPS Network Solutions Limited | Information & communication | 2005 |
| IQC Tech Services Ltd | Professional & scientific | 2021 |
| Iris Media Ltd | Administrative & support | 2010 |
| Iron and Oak Contracting Ltd | Construction | 2026 |
| Irum Holdings Limited | Professional & scientific | 2003 |
| Irum Properties Limited | Real estate | 1973 |
| Irwell Finance Limited | Arts & recreation | 2025 |
| IS Electrics Ltd | Professional & scientific | 2021 |
| Isaac Hannah Limited | Health & social care | 2015 |
| Isfali HMA Limited | Professional & scientific | 2017 |
| Ished Co., Limited | Wholesale & retail | 2025 |
| ISI Courier Limited | Transport & logistics | 2023 |
| Isiwakomen Line Ltd | Wholesale & retail | 2025 |
| ISO Healthcare Ltd | Health & social care | 2023 |
| Istanbul Flames Plus Ltd | Hospitality | 2026 |
| Isupply-International Supply Holdings Group Limited | Information & communication | 2018 |