| IBA Tech Limited | Information & communication | 2025 |
| Ibcs-Primax Software Ltd | Information & communication | 2006 |
| Ibex Apparel UK Ltd | Manufacturing | 2019 |
| Ibfs Consulting Limited | Hospitality | 2009 |
| Ibfs Private Clients Limited | Information & communication | 2009 |
| IBK Consulting Limited | Wholesale & retail | 2008 |
| IBL Grocer Store Ltd | Wholesale & retail | 2023 |
| Ibndawood Limited | Construction | 2018 |
| Ibolsterit Limited | Information & communication | 2025 |
| Ibrahim Global Traders Ltd | Wholesale & retail | 2025 |
| Ibrown Limited | Health & social care | 2017 |
| IBS Motors Ltd | Wholesale & retail | 2022 |
| IBT Consult Ltd | Information & communication | 2006 |
| Icare UK & Recruitment Ltd | Health & social care | 2020 |
| ICC London Ltd | Professional & scientific | 2023 |
| ICD Properties Ltd | Real estate | 2022 |
| Ice & Cakes Ltd | Hospitality | 2019 |
| Ice Fusion Limited | Hospitality | 2021 |
| Ice Mobile Security Ltd | Administrative & support | 2016 |
| Ice One Ruislip Ltd | Hospitality | 2025 |
| Ice Two Barnet Ltd | Hospitality | 2025 |
| Icecabin Limited | Hospitality | 2026 |
| Iceline Trading Limited | Wholesale & retail | 1998 |
| Icenatiion (Holdings) Limited | Financial services | 2021 |
| Icenatiion Limited | Hospitality | 2019 |
| Icloud Support Ltd | Wholesale & retail | 2010 |
| Icon Academy Martial Arts & Fitness Ltd | Arts & recreation | 2025 |
| Icon Building & Carpentry Ltd | Manufacturing | 2023 |
| Iconic Cars Limited | Wholesale & retail | 2023 |
| Iconic Design Builders Limited | Other services | 2014 |
| Iconic Homes Ltd | Construction | 2022 |
| Iconica Services Ltd | Professional & scientific | 2020 |
| Iconix Autostyling Ltd | Wholesale & retail | 2021 |
| Icons Mobile Barber Ltd | Wholesale & retail | 2022 |
| Ictps Ltd | Information & communication | 2007 |
| Icuk Computing Services Ltd | Information & communication | 2001 |
| ID5 Intensive Defensive Ltd | Education | 2022 |
| IDC Interiors Limited | Construction | 2009 |
| Ideahl CY23 Limited | Construction | 2016 |
| Ideahl Developments Limited | Construction | 2014 |
| Ideal Carz Limited | Wholesale & retail | 2017 |
| Ideal Freehold Management Ltd | Real estate | 2011 |
| Ideal Glass and Glazing Limited | Construction | 2011 |
| Ideal Mortgages Limited | Financial services | 2002 |
| Ideal Place (London) Limited | Real estate | 2003 |
| Ideal Procurement Ltd | Administrative & support | 2013 |
| Ideal Properties Limited | Households | 2009 |
| Ideal Properties Online Limited | Construction | 2012 |
| Ideal Stone Ltd | Administrative & support | 2015 |
| Ideas Investments Ltd | Real estate | 2020 |
| Ideas Residential Limited | Real estate | 2026 |
| Ideation Global Limited | Information & communication | 2019 |
| Ideho Security Limited | Administrative & support | 2010 |
| Ideliverability Ltd | Information & communication | 2024 |
| Idhaya Company Ltd | Real estate | 2026 |
| IDM Decorator Ltd | Construction | 2015 |
| IDM International Ltd | Education | 2021 |
| Idman Autos Ltd | Wholesale & retail | 2024 |
| Idnak Software Solutions Ltd | Information & communication | 2016 |
| Idol Trade Ltd | Wholesale & retail | 2025 |
| Idoma Community UK CIC | Education | 2026 |
| IDT Building Services Ltd | Construction | 2017 |
| Idylla Limited | Administrative & support | 2026 |
| IE Abroad Ltd. | Administrative & support | 2011 |
| Iecs Integrated Services Ltd | Education | 2017 |
| Iefs 17 Limited | Transport & logistics | 2017 |
| IF Beauty Limited | Other services | 2026 |
| IFE Props Ltd | Real estate | 2025 |
| Ifego Services Limited | Transport & logistics | 2018 |
| Iffi Production Ltd | Information & communication | 2023 |
| Ifield Place Management Company Limited | Households | 2011 |
| Ifien Limited | Real estate | 2017 |
| Ifix Centre Limited | Other services | 2013 |
| IFM Business Ltd | Other services | 2024 |
| IFM Trade Sales Ltd | Wholesale & retail | 2021 |
| Ifocus Consulting Limited | Professional & scientific | 2014 |
| Iforia Technologies Ltd | Professional & scientific | 2024 |
| Ignite Fire Safety Limited | Public administration | 2021 |
| Ignite Young Minds CIC | Administrative & support | 2024 |
| Igrace Ltd | Transport & logistics | 2014 |
| IGS Consultancy Ltd | Professional & scientific | 2024 |
| IH Banqueting Limited | Hospitality | 2025 |
| Ihybrid Limited | Information & communication | 2016 |
| II Estates II Ltd | Administrative & support | 2024 |
| IIA Consulting Limited | Information & communication | 2023 |
| III Thrones Ltd | Health & social care | 2021 |
| IIM Transport Ltd | Transport & logistics | 2020 |
| Iinpersonconnections C.I.C. | Wholesale & retail | 2024 |
| Iios Ltd | Wholesale & retail | 2021 |
| Iita Limited | Professional & scientific | 1999 |
| Ijytzu Trans Ltd | Transport & logistics | 2026 |
| IKE Papa Ltd | Transport & logistics | 2019 |
| Ikigai Global Ltd | Real estate | 2021 |
| Ikkensports Limited | Extraterritorial | 2014 |
| IKM Business Services Ltd | Administrative & support | 2022 |
| IKO Corporation Limited | Transport & logistics | 2019 |
| Ikon Productions Limited | Information & communication | 1988 |
| Iksas Care Services Ltd | Health & social care | 2021 |
| Ikshareef Ltd | Health & social care | 2022 |
| IL Magnifico SW7 Ltd | Professional & scientific | 2019 |