| ILE WA Ltd | Real estate | 2021 |
| Ilford Bicycles Ltd | Wholesale & retail | 2026 |
| Ilidio Jardim Carpentry Ltd | Construction | 2026 |
| Illumination Consulting Ltd | Information & communication | 2012 |
| Illusion Property Limited | Real estate | 2017 |
| Illuszionz Media Ltd | Professional & scientific | 2022 |
| Iloba Homes Limited | Real estate | 2024 |
| Ilomzee Consulting UK Ltd | Professional & scientific | 2016 |
| IM Beauty Academy Ltd | Other services | 2019 |
| Imach Technologies UK Ltd | Information & communication | 2024 |
| Image Consult Ltd | Construction | 2022 |
| Images Salon Limited | Other services | 2006 |
| Imaginashen Ltd | Real estate | 2020 |
| Imagination Consulting Ltd | Professional & scientific | 1999 |
| Imagine 10K Ltd | Professional & scientific | 2018 |
| Imagine Believe Limited | Arts & recreation | 2010 |
| Imeraj Investments Ltd | Real estate | 2025 |
| Imex International Group Limited | Wholesale & retail | 2013 |
| IMM Advisory UK Limited | Real estate | 2024 |
| Immanuel Day Care and Nursery Ltd | Health & social care | 2019 |
| Immanuel Welfare Team Ltd | Other services | 2025 |
| Immediatags Solutions Ltd | Professional & scientific | 2024 |
| Imor Construction Ltd | Construction | 2024 |
| Imortalis Technology Ltd | Health & social care | 2024 |
| Impact Motor Services Limited | Wholesale & retail | 2026 |
| Impact Utilities Limited | Construction | 2014 |
| Imparator Green Energy Ltd | Energy | 2011 |
| Impecc Global Limited | Wholesale & retail | 2007 |
| Impecc Properties Limited | Real estate | 2016 |
| Imperiah Studios Ltd | Information & communication | 2024 |
| Imperial Clean Services Ltd | Administrative & support | 2026 |
| Imperial Ductwork Manufacturing Limited | Manufacturing | 2001 |
| Imprint Design Limited | Information & communication | 2007 |
| Imulep Ltd | Real estate | 2019 |
| Imwa CIC | Administrative & support | 2012 |
| IN Color Productions Limited | Information & communication | 2025 |
| IN Focus Surveys Limited | Construction | 2018 |
| IN HIM Solutions Limited | Wholesale & retail | 2025 |
| IN Holdings Ltd | Construction | 2015 |
| IN Vega Ltd | Wholesale & retail | 2025 |
| In-Security Counselling Ltd | Education | 2022 |
| Inbuild Online Limited | Wholesale & retail | 2024 |
| Inc IT Solutions Ltd | Information & communication | 2018 |
| Inca Property Enterprises Limited | Professional & scientific | 1962 |
| Incaforce Civil Engineering Limited | Construction | 1983 |
| Inclusive Inventions Limited | Wholesale & retail | 2024 |
| Indalo Property Services Ltd | Construction | 2024 |
| Independence Finance Ltd | Financial services | 2013 |
| Independent Ticket Exchange & Brokerage Limited | Other services | 2000 |
| Index Enterprises Limited | Wholesale & retail | 2023 |
| Indexco Ltd | Real estate | 2018 |
| Indian Donald by Sonia Ltd | Hospitality | 2024 |
| Indian Food Flavours Ltd | Hospitality | 2024 |
| Indian Restaurant (Dartford) Ltd | Hospitality | 2020 |
| Indigo Lifts Group Limited | Financial services | 2022 |
| Indigo Lifts Limited | Professional & scientific | 2019 |
| Indus Care Ltd | Real estate | 2018 |
| Industrial Access Services Limited | Construction | 2007 |
| Infiniti Estates Ltd | Real estate | 2020 |
| Infinitidata Solutions (Idsl) Limited | Other services | 2023 |
| Infinity BC Limited | Manufacturing | 2015 |
| Infinity Prestige Properties Ltd | Real estate | 2024 |
| Infinity Video Limited | Information & communication | 2002 |
| Inflan Ltd | Information & communication | 2025 |
| Infoasset Limited | Information & communication | 2002 |
| Infointegral Limited | Information & communication | 2021 |
| Infomagna Ltd | Information & communication | 2023 |
| Ingenious Data Consultancy Limited | Information & communication | 2025 |
| Ingress Logistics Limited | Transport & logistics | 2024 |
| Inioluwa Limited | Health & social care | 2018 |
| Initiative International UK Ltd | Other services | 2009 |
| Inkeys Limited | Other services | 2016 |
| Inner City Environmental Ltd | Water & waste | 2006 |
| Innercity Fire Solutions Ltd | Public administration | 2025 |
| Innercity Scaffolding Limited | Construction | 2015 |
| Innostim Sports Management Limited | Arts & recreation | 2021 |
| Innova Systems Solution Ltd | Information & communication | 2018 |
| Innovate Invest Ltd | Construction | 2017 |
| Innovate Trade Investments Limited | Extraterritorial | 2015 |
| Innovate Trade Limited | Real estate | 2004 |
| Innovation Contractors Construction Ltd | Administrative & support | 2019 |
| Innovation Contractors Ltd | Administrative & support | 2019 |
| Innovation Plumbing & Heating Ltd | Construction | 2010 |
| Innovation Tribe Ltd | Professional & scientific | 2017 |
| Innovative and Infinite Ideas Ltd | Information & communication | 2022 |
| Innovative Design Studio Ltd | Wholesale & retail | 2020 |
| Innovative Portfolio Management Limited | Financial services | 2017 |
| Inourheart Ltd | Health & social care | 2024 |
| Inpah Ltd | Information & communication | 2024 |
| Insan Publishing Ltd | Wholesale & retail | 2025 |
| Inserv Technologies UK Limited | Construction | 2018 |
| Inside OUT Contracts Limited | Manufacturing | 1993 |
| Insight Realtor Ltd | Real estate | 2021 |
| Insightsdot Consultancy Limited | Information & communication | 2021 |
| Insightsdot Technologies Ltd | Information & communication | 2017 |
| Insp Consultants Ltd | Administrative & support | 2021 |
| Inspirec Ltd | Administrative & support | 2019 |
| Inspired Mindz CIC | Professional & scientific | 2023 |
| Installation Squad AV Limited | Administrative & support | 2013 |
| Installworld - LDN Ltd | Professional & scientific | 2010 |