| Ifrosa Sales Ltd | Wholesale & retail | 2024 |
| Igneous Networks Limited | Information & communication | 2007 |
| Ignition Labs Limited | Information & communication | 2024 |
| Igourmet Ltd | Hospitality | 2026 |
| IJA Property Ltd | Construction | 2016 |
| IJJ Data Bridge Limited | Information & communication | 2026 |
| IJT Consultancy Limited | Professional & scientific | 2024 |
| ILF Running Limited | Arts & recreation | 2026 |
| Iliffe Estates Limited | Real estate | 2021 |
| Illuminate Lighting and Design Ltd | Wholesale & retail | 2023 |
| Ilmenite Construction and Maintenance Ltd | Construction | 2023 |
| Ilmenite Ltd | Real estate | 2019 |
| Ilmors Ltd | Real estate | 2018 |
| Iloya Africana Limited | Transport & logistics | 2025 |
| IM Design Consultancy Limited | Professional & scientific | 2025 |
| IM Land and Property Limited | Real estate | 2017 |
| Image Scan Holdings PLC | Manufacturing | 1995 |
| Image Scan Limited | Professional & scientific | 1995 |
| Image Signs and Solutions Limited | Construction | 2005 |
| Images Hair Salon Ltd | Other services | 2015 |
| Imagination Thirty Five Limited | Professional & scientific | 2014 |
| Imaginative Leisure Limited | Hospitality | 2018 |
| Imagine Interiors Limited | Construction | 2001 |
| Imaging Analytics Ltd | Professional & scientific | 2021 |
| Imago @ Loughborough Limited | Hospitality | 1989 |
| Imbue Loughborough Ltd | Other services | 2018 |
| Immunex Limited | Wholesale & retail | 2025 |
| Immunoconsulting Limited | Professional & scientific | 2016 |
| Imogen Lathbury-Ling Ltd | Information & communication | 2023 |
| Imosphere Ltd | Information & communication | 1993 |
| Impact Web Works Ltd | Information & communication | 2025 |
| Imperial Business Consulting Limited | Professional & scientific | 2016 |
| Imperial Law Legal Services Ltd | Professional & scientific | 2016 |
| Imperial Wealth Management Ltd | Professional & scientific | 2024 |
| Impro Solutions UK Ltd | Wholesale & retail | 2019 |
| Impulse Luxury Ltd | Transport & logistics | 2025 |
| Imteks-Wipers Limited | Wholesale & retail | 2014 |
| In-Cycle Ltd | Administrative & support | 2012 |
| In-Synq Solutions Ltd | Administrative & support | 2016 |
| Inca Holding Limited | Financial services | 2019 |
| Inca Jewellery Limited | Wholesale & retail | 1985 |
| Incentivizeme Ltd | Information & communication | 2025 |
| Indian Rooster (Loughborough) Ltd | Hospitality | 2024 |
| Indigo Lets Limited | Real estate | 2020 |
| Indigo Mechanical Limited | Construction | 2017 |
| Industrial & Marine Silencers Limited | Manufacturing | 1991 |
| Industrial Doors Outlet Ltd | Wholesale & retail | 2024 |
| Industrial Neuroscience Ltd | Professional & scientific | 2019 |
| Inevitable Construction Ltd | Construction | 2023 |
| Infinity and Beyond Renovations Ltd | Real estate | 2023 |
| Infinity Bridge Ltd | Financial services | 2024 |
| Inflator Pads Ltd | Manufacturing | 2023 |
| Infonomics Limited | Information & communication | 2007 |
| Informed Performance Limited | Health & social care | 2015 |
| Infosmith Ltd | Information & communication | 2020 |
| Infozyme Limited | Professional & scientific | 2002 |
| Infrastructure Engineering Solutions Ltd | Administrative & support | 2011 |
| Ingenious Health Tech Ltd | Professional & scientific | 2024 |
| Inglewood Grange Ltd | Real estate | 2020 |
| Inhabit Homes and Interiors Ltd | Construction | 2024 |
| Inherit Skills Limited | Education | 2017 |
| Inlair Group Nottingham Ltd. | Other services | 2024 |
| Innergyhealing Limited | Health & social care | 2016 |
| Innocent Fellas Ltd | Wholesale & retail | 2024 |
| Innospective Limited | Professional & scientific | 2017 |
| Innovation CSL Limited | Health & social care | 2025 |
| Innovation Funding Limited | Professional & scientific | 2012 |
| Innovative Cyber Vision Limited | Information & communication | 2003 |
| Innovera Holdings Limited | Information & communication | 2016 |
| Innoveterinary Limited | Professional & scientific | 2014 |
| Innovitas Ltd | Real estate | 2021 |
| Innowage Limited | Information & communication | 2023 |
| Inresource Limited | Professional & scientific | 2010 |
| Inside OUT Tennis Ltd | Arts & recreation | 2010 |
| Insight Accountants Ltd | Professional & scientific | 2013 |
| Insite Business Technology Ltd | Information & communication | 2000 |
| Inspirational Magazine Limited | Administrative & support | 2011 |
| Inspire Young People & Families CIC | Education | 2025 |
| Installair Ltd | Manufacturing | 2014 |
| Institute of Swimming Limited | Other services | 1983 |
| Insyte Consultancy Ltd | Professional & scientific | 2016 |
| Integer Consulting (Emea) Ltd | Professional & scientific | 2023 |
| Integrated Environmental Health & Safety Consultancy Ltd | Professional & scientific | 2026 |
| Integrated Power Technology Limited | Extraterritorial | 1997 |
| Integrated Power Technology UK Limited | Information & communication | 2002 |
| Integrated Space Management Limited | Extraterritorial | 1989 |
| Integrated Technical and Engineering Services Ltd | Construction | 2023 |
| Integrity Lighting Solutions Ltd | Manufacturing | 2019 |
| Intelect Services Limited | Construction | 2017 |
| Intelligent Energy Limited | Manufacturing | 2000 |
| Intelligent Financial Advisory Services Ltd | Financial services | 2024 |
| Intelligent Medical Group Limited | Wholesale & retail | 2017 |
| Intelligent Telescopic Turbines Ltd | Extraterritorial | 2012 |
| Intelligent Triathlon Training Ltd | Arts & recreation | 2018 |
| Inter-Lect (UK) Limited | Construction | 2013 |
| Interac Design Ltd | Professional & scientific | 1998 |
| Intergalactic Sabre Masters Ltd | Other services | 2016 |
| International Association of Registered Financial Planners | Other services | 2008 |
| International Scripts Limited | Other services | 2024 |
| International Terminal Solutions Limited | Information & communication | 2002 |