| I-Drive Mouldings Limited | Construction | 2026 |
| I-Mage Communications Ltd | Professional & scientific | 2003 |
| I-Tech Solutions (Euro) Ltd | Information & communication | 2009 |
| I-Visual Solutions Limited | Information & communication | 2009 |
| I.L.S. International Logistics Services Limited | Professional & scientific | 2017 |
| I.T. Financial Trading Limited | Administrative & support | 1999 |
| I.T.S. Interactive UK Ltd | Administrative & support | 2010 |
| I1 Group Ltd | Construction | 2015 |
| IAC Recruitment Limited | Administrative & support | 2025 |
| Iac-Search Limited | Administrative & support | 2009 |
| Iain Andrews Ltd | Hospitality | 2012 |
| Ianh Services Ltd | Administrative & support | 2023 |
| IAS International Aircraft Services UK Limited | Administrative & support | 2024 |
| Ibathurst Consulting Ltd | Professional & scientific | 2020 |
| IBF Advisory Limited | Administrative & support | 2024 |
| Ibiza Properties Ltd | Real estate | 2018 |
| IBO Cooling Limited | Manufacturing | 2019 |
| Ibrishimov Limited | Construction | 2013 |
| Icab Pods Limited | Hospitality | 2016 |
| ICB Defence Services Ltd | Construction | 2021 |
| ICB General Building and Civil Engineering Ltd | Construction | 2012 |
| ICB Group London Ltd | Financial services | 2019 |
| ICB Merchants Ltd | Wholesale & retail | 2022 |
| ICB Services Ltd | Construction | 2022 |
| Icds Constructors (UK) Ltd | Administrative & support | 1997 |
| Icds Recruitment Consultants (UK) Ltd | Extraterritorial | 1999 |
| Ice Cold in Alex Limited | Extraterritorial | 2007 |
| Ichinfest Consulting Limited | Information & communication | 2014 |
| Icogency Limited | Real estate | 2014 |
| Icon Holdings 68 Limited | Financial services | 2023 |
| Icon Holdings Group Ltd | Hospitality | 2020 |
| Icon Media Limited | Information & communication | 2013 |
| Icon Property Corp Limited | Real estate | 1996 |
| Iconic Vinyl Art Ltd | Wholesale & retail | 2025 |
| Iconify Limited | Professional & scientific | 2019 |
| ICT Worldwide Commodities Trading Limited | Administrative & support | 2014 |
| IDA Recruitment Ltd | Administrative & support | 2018 |
| Idcc Properties Ltd | Real estate | 2019 |
| Ideal Balham Cafe Limited | Administrative & support | 2018 |
| Ideal Cafe Ltd | Administrative & support | 2011 |
| Ideal Cafe Welling Limited | Administrative & support | 2017 |
| Ideal Ecco Cafe Limited | Administrative & support | 2024 |
| Ideal GAS and Plumbing Ltd | Construction | 2020 |
| Ideal Glass L Limited | Construction | 2024 |
| Ideal Hair & Beauty Ltd | Administrative & support | 2021 |
| Ideas Consult Limited | Professional & scientific | 2015 |
| Ideas Food Consultancy Ltd | Professional & scientific | 2023 |
| Identify (IP) Limited | Administrative & support | 2016 |
| Ider Furniture Ltd | Extraterritorial | 2024 |
| IDL Admin Limited | Administrative & support | 2025 |
| IDL Property Developments Ltd | Construction | 2023 |
| Idlem Ltd | Professional & scientific | 2022 |
| Ifdf Holdings Limited | Real estate | 2026 |
| Ifmt Services Ltd | Information & communication | 2001 |
| IG Construction Limited | Construction | 2010 |
| Igarden Ltd | Administrative & support | 2025 |
| IGC London Ltd | Arts & recreation | 2020 |
| Igigas Consulting Limited | Information & communication | 2011 |
| Ignatius Holdings Limited | Real estate | 2015 |
| Igoeverywhere Ltd | Administrative & support | 2024 |
| Ihsana Limited | Professional & scientific | 2025 |
| Ikenga Wellness Ltd | Arts & recreation | 2026 |
| IKF Business Services Limited | Professional & scientific | 2004 |
| Ikki Productions Ltd | Information & communication | 2015 |
| IKM Chauffeurs Ltd | Administrative & support | 2015 |
| ILA Homes Ltd | Real estate | 2018 |
| Ilanda Forensic Accounting Services Ltd | Information & communication | 2018 |
| Ilapila Ltd | Health & social care | 2018 |
| Ilford Doors & Windows Limited | Manufacturing | 2017 |
| Illicium Ltd | Wholesale & retail | 2021 |
| IMA Food Ltd | Hospitality | 2023 |
| IMA Guild Ltd | Education | 2025 |
| Imaan Law Ltd | Professional & scientific | 2019 |
| Image Health Care and Recruitment Services Ltd | Health & social care | 2012 |
| Imaginary Cloud Holdings Limited | Financial services | 2026 |
| Imaginary Cloud Limited | Information & communication | 2021 |
| Imece Network CIC | Education | 2020 |
| Immaculate Ventures Limited | Professional & scientific | 2010 |
| Immediate Network Limited | Information & communication | 2000 |
| Immersive Design Academy | Education | 2025 |
| Immersive Health UK Ltd | Administrative & support | 2021 |
| Immersive Props Ltd | Information & communication | 2024 |
| Immk Properties Ltd | Real estate | 2025 |
| Immobiliser Fit Ltd | Administrative & support | 2024 |
| Impact 360 Ltd | Information & communication | 2022 |
| Impact 360 Productions Limited | Manufacturing | 2025 |
| Impact IP Limited | Information & communication | 2020 |
| Imperial Court (Finchley) Management Limited | Households | 1972 |
| Imperial Court Management Limited | Households | 1996 |
| Imperial Lance Limited | Hospitality | 2019 |
| Imperial Leadership Academy Limited | Health & social care | 2007 |
| Imperium AG Ltd | Health & social care | 2021 |
| Impero Estates Limited | Real estate | 2020 |
| Impetus Consulting Limited | Information & communication | 2015 |
| Importplug Ltd | Wholesale & retail | 2023 |
| Impossible Telecom Limited | Information & communication | 2016 |
| IN ALL Media Limited | Information & communication | 2015 |
| IN Harmony (London) Limited | Health & social care | 2006 |
| IN HIS Wings Healthcare Ltd | Health & social care | 2022 |
| IN the LAB Ltd. | Manufacturing | 2016 |