| Ibel Limited | Professional & scientific | 2017 |
| Iberian Agricultural Consultants LP | | 2009 |
| Iberian Vegetable Traders LP | | 2009 |
| IBS Consultancy Ltd | Professional & scientific | 2024 |
| Icare Manchester Ltd | Health & social care | 2022 |
| Iceni Mastermind Group Ltd | Education | 2025 |
| Ichi Fresh Ltd | Hospitality | 2026 |
| Icon Business Support Limited | Professional & scientific | 2015 |
| Iconic Bathrooms Ltd | Construction | 2015 |
| Iconyc Limited | Information & communication | 2024 |
| ICP Properties Ltd | Real estate | 2021 |
| ICS Homes Limited | Construction | 2009 |
| Idahoshop Limited | Wholesale & retail | 2021 |
| Idris Ramli Medical Ltd | Health & social care | 2012 |
| Ignite Safety Limited | Professional & scientific | 2022 |
| Ikkicon Ltd | Wholesale & retail | 2025 |
| Imagine Childcare Limited | Health & social care | 2020 |
| Immys Ltd | Wholesale & retail | 2020 |
| Impact Consulting and Support Limited | Professional & scientific | 2015 |
| Impact Europe CIC | Arts & recreation | 2025 |
| Impact Sport Solutions Limited | Professional & scientific | 2015 |
| Impair Ltd | Information & communication | 2019 |
| Imperial Trades and Projects Ltd | Construction | 2014 |
| Imperial Treasures Limited | Real estate | 2020 |
| IN the Interim Ltd | Administrative & support | 2023 |
| IN4RTECH Solutions Ltd | Information & communication | 2015 |
| Incentive for Trading & Services UK Ltd | Wholesale & retail | 2019 |
| Incia Projects Ltd. | Real estate | 2012 |
| Incker Network Technology Limited | Information & communication | 2023 |
| Inclusion Collective Aotearoa Network Ltd | Administrative & support | 2025 |
| Inclusive Case Management Limited | Health & social care | 2023 |
| Indexsio Digital Ltd | Information & communication | 2018 |
| Indiepoint Ltd | Information & communication | 2026 |
| Indus Consulting Ltd | Information & communication | 2024 |
| Industrial System Solutions Ltd | Manufacturing | 2002 |
| Infinite Bridge Ltd | Transport & logistics | 2021 |
| Infinite Design Consultants Limited | Administrative & support | 2008 |
| Infiniti Fitness 121 Limited | Arts & recreation | 2013 |
| Info Dynamic Systems Ltd | Information & communication | 2019 |
| Infosphere Management Limited | Administrative & support | 2011 |
| Infrabuild Solutions Ltd | Construction | 2026 |
| Infrasafe UK Limited | Professional & scientific | 2012 |
| Infuse by DR Bryan Ltd | Health & social care | 2025 |
| Ingledene Court Limited | Households | 1970 |
| Inmotion Beauty Limited | Wholesale & retail | 2020 |
| Inner Dynamics Ltd | Health & social care | 2018 |
| Inner Industries Limited | Wholesale & retail | 2022 |
| Innotatzit Solutions Limited | Information & communication | 2023 |
| Innova Medical (UK) Operations, Ltd | Manufacturing | 2021 |
| Innova Recruitment Limited | Administrative & support | 2018 |
| Innova Systems Limited | Manufacturing | 2002 |
| Innovate Supply Chain Consultants Ltd | Information & communication | 2018 |
| Innovative Biotech Engineering Limited | Professional & scientific | 2024 |
| Inovance Technology UK Limited | Information & communication | 2026 |
| Inovita Laboratory Ltd | Wholesale & retail | 2014 |
| Insale Limited | Wholesale & retail | 2017 |
| Inside Property Investing Limited | Professional & scientific | 2018 |
| Inspire Gold Sport Services Limited | Professional & scientific | 2015 |
| Inspire Group Services Limited | Other services | 2019 |
| Inspire Merchant Services Limited | Other services | 2019 |
| Inspire Payment Services Limited | Other services | 2019 |
| Inspiring Learners Multi Academy Trust | Education | 2017 |
| Instrade Legal Consulting Limited | Professional & scientific | 2020 |
| Intec for Business Limited | Information & communication | 1995 |
| Intelligent Asset Solutions Limited | Wholesale & retail | 2009 |
| Intelligent Controls Limited | Construction | 2010 |
| Intense Clothing Limited | Wholesale & retail | 2011 |
| Interior Solutions (Bolton) Limited | Construction | 2013 |
| Interiors Realisations Ltd | Construction | 2010 |
| International British Business School Ltd | Real estate | 2021 |
| International Business School Ltd | Education | 2022 |
| International Marine Supplies Ltd | Construction | 2019 |
| Intero Property Solutions Ltd | Real estate | 2022 |
| Interpark International Limited | Information & communication | 2009 |
| Into Project Limited | Professional & scientific | 2017 |
| Intrinsic Resourcing Limited | Extraterritorial | 2020 |
| Intro Recruitment Group Limited | Administrative & support | 2021 |
| Investinyiu Limited | Real estate | 2023 |
| INVICTUS6 Limited | Health & social care | 2023 |
| Invoice Solution Services Limited | Information & communication | 2018 |
| Ip-Netix Limited | Information & communication | 2008 |
| Ipensions Group Limited | Financial services | 1998 |
| Ipensions Group Ssas Trustees Limited | Financial services | 1998 |
| Ipensions Group Trustees Limited | Financial services | 2012 |
| Ipensions Wealth Limited | Financial services | 2021 |
| Iproperties North West Ltd | Real estate | 2017 |
| Iron Lotus Limited | Other services | 2024 |
| Ironbark Consulting (Analytics) Limited | Information & communication | 2026 |
| Irwell Valley (Developments) Limited | Construction | 2000 |
| Isallt Lodges Management Company (Trearddur Bay) Limited | Households | 1979 |
| ISD Logistic Ltd | Transport & logistics | 2022 |
| Isfam Ltd | Real estate | 2023 |
| Isfam Traders Ltd | Wholesale & retail | 2024 |
| ISH Productions Limited | Administrative & support | 2023 |
| Isha Management Consulting Limited | Professional & scientific | 2005 |
| Islam Healthcare Limited | Health & social care | 2023 |
| Ismartt Limited | Information & communication | 2019 |
| Isolation Cookout Ltd | Wholesale & retail | 2025 |
| ISR Property Limited | Financial services | 2016 |
| ISR Recruitment Limited | Administrative & support | 2005 |