| Innovative Services Ltd | Financial services | 2022 |
| Innovo Consulting Limited | Information & communication | 2012 |
| Inovium Ltd | Construction | 2017 |
| Insden Ltd | Hospitality | 2021 |
| Inspire U 4U CIC | Information & communication | 2025 |
| INSPIRE2CARE Limited | Administrative & support | 2016 |
| Inspiredcode Ltd | Information & communication | 2018 |
| Inspiring Elegance Ltd | Wholesale & retail | 2021 |
| Inspiring Events Ltd | Arts & recreation | 2023 |
| Instyle Fashion (UK) Ltd | Wholesale & retail | 2022 |
| Insurance Technology Forums Limited | Administrative & support | 2011 |
| Insureon Commercial Limited | Extraterritorial | 2008 |
| Insureon Group Limited | Financial services | 2008 |
| Insureon Limited | Financial services | 2008 |
| Integra Psychiatry Limited | Health & social care | 2023 |
| Integral Consulting Limited | Professional & scientific | 2017 |
| Integral Contractors Limited | Construction | 2017 |
| Integral Management Solutions (IMS) Limited | Professional & scientific | 2015 |
| Integral Recruitment Ltd | Administrative & support | 2020 |
| Integrated Healthcare Professionals Ltd | Administrative & support | 2022 |
| Integritas Education Recruitment Ltd | Administrative & support | 2018 |
| Integrity Insight Consulting Limited | Professional & scientific | 2025 |
| Integrity Isolutions Limited | Administrative & support | 2025 |
| Integrum Fire Ltd | Construction | 2018 |
| Intelabuild Limited | Construction | 2023 |
| Intelligent Steel Solutions Limited | Manufacturing | 2014 |
| Interabang Limited | Professional & scientific | 2010 |
| Interbay Asset Finance Limited | Financial services | 2006 |
| Interbay Funding, Ltd. | Financial services | 2005 |
| Interbuilding Ltd | Construction | 2021 |
| Interelay Solutions Limited | Information & communication | 2023 |
| Interior Logistics Limited | Construction | 2012 |
| Interior Surveying Services Ltd | Professional & scientific | 2012 |
| Interior Wrap Solutions Limited | Extraterritorial | 2021 |
| Internal Projects Limited | Other services | 2014 |
| International Society of Contact Lens Specialists Limited | Other services | 1976 |
| Interpole Resins Ltd | Administrative & support | 2007 |
| Intime Profit LLP | | 2010 |
| Into Account Limited | Professional & scientific | 2014 |
| Intragents Ltd | Professional & scientific | 2019 |
| Intrepid-Tdk Limited | Health & social care | 2019 |
| Intrinsic Care (Canterbury and Coastal) Limited | Health & social care | 2023 |
| Intrinsic Care (Manchester) Limited | Health & social care | 2023 |
| Intrinsic Estate Limited | Real estate | 2020 |
| Inventory Line Limited | Professional & scientific | 2025 |
| Invero Homes Ltd | Real estate | 2025 |
| Invicta Coaching and Consulting Ltd | Professional & scientific | 2024 |
| Invicta Generators Limited | Manufacturing | 2014 |
| Invicta Insurance Brokers Limited | Professional & scientific | 2003 |
| Invicta Property Solutions Limited | Professional & scientific | 2024 |
| Invicta Reinforcing Limited | Construction | 2016 |
| Invicta Safety Limited | Professional & scientific | 2016 |
| Iona Real Estate Limited | Real estate | 2024 |
| IP Fireline Ltd | Construction | 2025 |
| IP Installations Limited | Manufacturing | 2002 |
| IP Support Hub Limited | Administrative & support | 2026 |
| IPL Design Limited | Administrative & support | 2013 |
| Iposhmedia Limited | Other services | 2025 |
| IQ Digital Limited | Information & communication | 2009 |
| IQL Bar Limited | Hospitality | 2019 |
| IQL Bar Trading Limited | Hospitality | 2022 |
| Iqra Asset Management Limited | Real estate | 2022 |
| Iremold Services Ltd | Construction | 2013 |
| Iron Handyman Ltd | Hospitality | 2021 |
| Ironmongery Innovations Limited | Administrative & support | 2013 |
| Isaac & Nisa Blackstone Ltd | Real estate | 2024 |
| Isabella's Catering Ltd | Hospitality | 2022 |
| Island BOY Ltd | Wholesale & retail | 2019 |
| Island Commercial Services Ltd | Other services | 2004 |
| Island Gray Limited | Professional & scientific | 2018 |
| Island Property Maintenance Kent Ltd | Construction | 2025 |
| Island Staycation Ltd | Hospitality | 2024 |
| ISM Club Ltd | Wholesale & retail | 2024 |
| Ismail Consulting Limited | Administrative & support | 2013 |
| Ismn Limited | Agriculture & fishing | 2018 |
| ISO Serious Limited | Professional & scientific | 2024 |
| Isofi Limited | Information & communication | 2020 |
| ISR Hockey World Limited | Manufacturing | 2020 |
| IT Manager Services Ltd | Information & communication | 2019 |
| IT Network Wizards Limited | Information & communication | 2024 |
| IT Serious Ltd | Information & communication | 2026 |
| Italy Dolce Italy Ltd | Hospitality | 2024 |
| Itertek Ltd | Professional & scientific | 2014 |
| Iulixtrans Ltd | Transport & logistics | 2023 |
| IVA Maitenance Ltd | Construction | 2016 |
| Ivansami Electric Ltd | Construction | 2025 |
| Ives Investments Limited | Real estate | 2002 |
| Ivinco Ltd | Information & communication | 2009 |
| Ivitta LLP | | 2008 |
| Ivitta Logistics Limited | Information & communication | 2014 |
| Ivittaapps Limited | Information & communication | 2014 |
| Ivory ROW Ltd | Administrative & support | 2025 |
| Ivory Security Limited | Administrative & support | 2006 |
| IVY League Care Limited | Health & social care | 2021 |
| IVY LET Properties Ltd | Real estate | 2022 |
| Iwade Property Enterprises Ltd | Households | 2016 |
| IWC Properties Limited | Professional & scientific | 2013 |
| Iwest Media Global Ltd | Manufacturing | 2023 |
| IWR Indian Ocean Ltd | Financial services | 2011 |
| Iyco Limited | Construction | 2009 |