| ID Furniture Solutions Ltd | Wholesale & retail | 2020 |
| Idaso UK Limited | Information & communication | 2023 |
| Idata Consultancy Ltd | Wholesale & retail | 2012 |
| IDD Properties LLP | | 2016 |
| Ideal Location Housing Limited | Hospitality | 2016 |
| Ideal Location Property Limited | Hospitality | 2011 |
| Ideal U.K. Limited | Health & social care | 1999 |
| Ideaworks International Limited | Professional & scientific | 2017 |
| Identis Limited | Extraterritorial | 2001 |
| Idesa UK Limited | Mining & quarrying | 2019 |
| Idev Limited | Information & communication | 1999 |
| Idika Consultancy Ltd | Other services | 2015 |
| IDK Utilities Ltd | Manufacturing | 2026 |
| IDL Barber Ltd. | Other services | 2018 |
| IDM Consulting Limited | Professional & scientific | 2019 |
| Idoya Cols Ltd | Professional & scientific | 2012 |
| Idrees Logistics Ltd | Transport & logistics | 2025 |
| Idwestt Property Development Limited | Real estate | 2024 |
| IE Property Management Ltd | Households | 2024 |
| IEL Holdings Ltd | Real estate | 2018 |
| IF Payroll Limited | Professional & scientific | 2014 |
| Ifeel Qualifications Ltd | Education | 2010 |
| Ifeoma Health Solutions Limited | Health & social care | 2024 |
| Ifinder Ltd | Hospitality | 2017 |
| IFM Services Ltd | Administrative & support | 2020 |
| Iglu Group Ltd | Administrative & support | 2016 |
| Ignite Business Communications Limited | Information & communication | 1998 |
| Igozal Limited | Wholesale & retail | 2025 |
| IH Watson Jewels Ltd | Manufacturing | 2026 |
| IJH Investments Limited | Real estate | 2018 |
| IJM Services Limited | Real estate | 2020 |
| IJS Associates (M&E) Limited | Professional & scientific | 2024 |
| IK804 Trading Ltd | Hospitality | 2024 |
| Ikarma Ltd | Professional & scientific | 2020 |
| Ikigaikarate Ltd | Arts & recreation | 2023 |
| Ikuno Limited | Administrative & support | 2025 |
| Ilford Pathology Services Limited | Health & social care | 2025 |
| Iliuta Logistics Ltd | Transport & logistics | 2018 |
| Illuminati Lighting UK Limited | Wholesale & retail | 2010 |
| Illumination Insight Ltd | Professional & scientific | 2024 |
| Illy's Living Ltd | Professional & scientific | 2025 |
| ILT Consulting Limited | Administrative & support | 2023 |
| Imagine Chelmsford Limited | Education | 2023 |
| Imagine Padel Ltd | Arts & recreation | 2025 |
| Imaging Services 123 Limited | Health & social care | 2019 |
| Imagraph Ltd | Information & communication | 2025 |
| Imaj Aesthetics Ltd | Other services | 2023 |
| Imarketing Ltd. | Professional & scientific | 2001 |
| Imbranding Ltd | Professional & scientific | 2018 |
| Imedia Systems Limited | Manufacturing | 2003 |
| Imind Limited | Manufacturing | 2004 |
| Imjassoc Limited | Administrative & support | 2017 |
| Immortal INK Limited | Other services | 2014 |
| Impacs Group Ltd | Professional & scientific | 2022 |
| Impact Electrical Distributors Limited | Wholesale & retail | 2003 |
| Impact HR Consulting Limited | Administrative & support | 2018 |
| Impact of WE CIC | Information & communication | 2023 |
| Impactus Medical Ltd | Health & social care | 2025 |
| Imperial Care Solutions Ltd | Health & social care | 2018 |
| Imperial Carriages Limited | Wholesale & retail | 2001 |
| Imperial Corporate Solutions Ltd | Administrative & support | 2026 |
| Imperial Day Nursery Limited | Health & social care | 2008 |
| Imperial Outlets Ltd | Wholesale & retail | 2020 |
| Imperial Park Management Limited | Real estate | 1994 |
| Imperial Thermal Solutions Limited | Construction | 2016 |
| Imperials Prestige Properties Ltd | Real estate | 1996 |
| Implemental Systems GBS Ltd. | Information & communication | 2016 |
| Implore Creative Ltd | Professional & scientific | 2025 |
| Improving Outcomes Ltd | Health & social care | 2017 |
| IMR Construction Limited | Construction | 2017 |
| Imropi Global Limited | Wholesale & retail | 2024 |
| IN2ACTION Limited | Arts & recreation | 2003 |
| Inabrows & Blush Beautify Limited | Other services | 2025 |
| Inbeauty Iuliana Aesthetics Ltd | Other services | 2023 |
| Inception Consultancy Group Limited | Professional & scientific | 2024 |
| Incert BIO Limited | Administrative & support | 2025 |
| Incredible Construction Ltd | Construction | 2022 |
| Incredible Pixel Properties Limited | Real estate | 2014 |
| Increment Group Limited | Extraterritorial | 2015 |
| Independent Insurance Surveys Limited | Financial services | 1997 |
| Independent Living Advocacy Essex Ltd | Professional & scientific | 2025 |
| Independent Photographers Association | Information & communication | 2013 |
| Independent Properties Europe Limited | Real estate | 2007 |
| Indievelo Ltd | Information & communication | 2023 |
| Inditgo Ltd | Manufacturing | 2014 |
| Indo Asian Foods Ltd | Wholesale & retail | 2013 |
| Indopak Essex Ltd | Hospitality | 2024 |
| Industrial Commercial Domestic Ltd | Construction | 2013 |
| Industrial Property Assets Limited | Real estate | 1999 |
| Industrial Recruitment Group Ltd | Administrative & support | 2025 |
| Industrial Training Holdings Limited | Financial services | 2021 |
| Industrial Training Services Ltd | Administrative & support | 1989 |
| Indy Consultancy Ltd | Professional & scientific | 2017 |
| Infinidea Technology and Consulting Services Limited | Information & communication | 2018 |
| Infinite Cleaning Group Ltd | Administrative & support | 2024 |
| Infinite Healthcare Services Ltd | Administrative & support | 2018 |
| Infinite Solutions LG Ltd | Transport & logistics | 2022 |
| Infinitelife Care Ltd | Administrative & support | 2021 |
| Infinitelife Group Ltd | Transport & logistics | 2019 |
| Infinitelife Homes Ltd | Administrative & support | 2026 |