| Illuminis Insight Software Limited | Information & communication | 2010 |
| Illustrate Architects Limited | Professional & scientific | 2022 |
| Illustrious Capital Ltd | Real estate | 2016 |
| Ilmex Limited | Water & waste | 1987 |
| Iloaded Ltd | Professional & scientific | 2017 |
| ILUV2EAT Limited | Information & communication | 2023 |
| IMA Property Maintenance Ltd | Construction | 2024 |
| Imaai Group Ltd | Administrative & support | 2021 |
| Imaansmart Ltd | Wholesale & retail | 2024 |
| Image Station Ltd | Professional & scientific | 2020 |
| Images Publishing Limited | Information & communication | 2002 |
| Imagimations Animation Ltd | Wholesale & retail | 2026 |
| Imagination Learning Ltd | Education | 2022 |
| Imagine (Crofts) Limited | Construction | 2025 |
| Imagine (Gresley) Ltd | Construction | 2021 |
| Imagine (Hightown) Ltd | Construction | 2020 |
| Imagine (Orchard END) Ltd | Construction | 2024 |
| Imagine Construction Ltd | Construction | 2007 |
| Imagine Gary Limited | Information & communication | 2019 |
| Imagine Presentations Limited | Administrative & support | 2003 |
| Imagine Property Rentals Limited | Real estate | 2012 |
| Imagine Tech Holdings Ltd | Financial services | 2025 |
| Imagine Tech Ltd | Information & communication | 2025 |
| Imaginer Ltd | Professional & scientific | 2016 |
| IMAKUL8 Body Scuplting Ltd | Other services | 2025 |
| Iman UK Federation Ltd | Other services | 2025 |
| Imanalizah Ltd | Real estate | 2026 |
| Imane Medicalcare Limited | Health & social care | 2016 |
| Imani 2020 Ltd | Health & social care | 2019 |
| Imanixbeauty Aesthetics & Training Academy Ltd | Other services | 2025 |
| Imara Welfare Community Interest Company | Other services | 2007 |
| Imarkuk Ltd | Manufacturing | 2020 |
| Imassx Limited | Wholesale & retail | 2025 |
| Imaya Technologies Ltd | Information & communication | 2017 |
| Imcon Limited | Professional & scientific | 2018 |
| Imelement CIC | Information & communication | 2023 |
| Imex Group Ltd | Wholesale & retail | 2022 |
| IMG Construction Services Limited | Construction | 2025 |
| Imgr Limited | Wholesale & retail | 2007 |
| IMI International Limited | Wholesale & retail | 1999 |
| Imig - Integration & Migration Limited | Administrative & support | 2006 |
| Immavester Limited | Health & social care | 2015 |
| Immediate Records Limited | Extraterritorial | 2005 |
| Immenseit Solutions Ltd | Information & communication | 2024 |
| Immersive Henna Ltd | Wholesale & retail | 2012 |
| Immobilier Prime Ltd | Real estate | 2024 |
| Immuone Ltd | Professional & scientific | 2019 |
| Impact for Success Limited | Wholesale & retail | 2014 |
| Impact League Limited | Wholesale & retail | 2025 |
| Impact Makers Ltd | Professional & scientific | 2013 |
| Impact Productions (Milton Keynes) Holdings Limited | Financial services | 2025 |
| Impact Productions (Milton Keynes) Limited | Administrative & support | 2006 |
| Impact Trading (UK) Ltd | Manufacturing | 2003 |
| Impact Tuition and Consulting Ltd | Education | 2014 |
| IMPACT24 Ltd | Extraterritorial | 2023 |
| Impactico CIC | Education | 2025 |
| Impacting Life Ltd | Information & communication | 2019 |
| Impakt Consulting Ltd | Professional & scientific | 2011 |
| Imperative Healthcare Ltd | Health & social care | 2019 |
| Imperial Luxury Ltd | Wholesale & retail | 2025 |
| Imperial Payments Limited | Professional & scientific | 2026 |
| Imperial Sales Ltd | Wholesale & retail | 2024 |
| Imperialix Security Ltd | Financial services | 2025 |
| Imperium & Libertas Ltd | Real estate | 2023 |
| Imperium Realm Ltd | Real estate | 2019 |
| Impero Mnkq Ltd. | Hospitality | 2022 |
| Impexa Ltd | Manufacturing | 2025 |
| Implants by DR Uzman Limited | Health & social care | 2022 |
| Importmyvehicle.Com Limited | Transport & logistics | 2006 |
| Impress Cleaners Limited | Other services | 2017 |
| Impress Shoes Limited | Wholesale & retail | 2025 |
| Impression Health Care and Beauty Limited | Health & social care | 2021 |
| Imprisk Ltd | Professional & scientific | 2015 |
| IMQ Certification (UK) Ltd | Professional & scientific | 2022 |
| Imserv Europe Limited | Administrative & support | 1992 |
| Imuli Events Ltd | Hospitality | 2023 |
| Imuli Ltd | Hospitality | 2020 |
| IN Abis Hands Ltd | Health & social care | 2020 |
| IN Eco Systems Limited | Construction | 2015 |
| IN Engagement Ltd | Information & communication | 2022 |
| IN Facilities Engagement Ltd | Information & communication | 2022 |
| IN Heaven at Home Limited | Wholesale & retail | 2012 |
| IN HIS Image Clothing Ltd | Wholesale & retail | 2026 |
| IN Need Ltd | Administrative & support | 2017 |
| IN Secure Management Ltd | Information & communication | 2022 |
| IN Summa Digital Ltd | Professional & scientific | 2026 |
| IN Switch Limited | Transport & logistics | 2015 |
| IN the Field Limited | Professional & scientific | 2020 |
| IN the Style Fashion Limited | Wholesale & retail | 2013 |
| IN Time Training Limited | Education | 2011 |
| IN2 Consult Ltd | Administrative & support | 2017 |
| IN2FAB Technology Ltd | Information & communication | 1997 |
| IN2FOOD Europe Limited | Wholesale & retail | 2014 |
| IN2TEC Holdings Limited | Administrative & support | 2002 |
| IN8 Expressions Limited | Health & social care | 2016 |
| IN8 Global Investments Ltd | Real estate | 2023 |
| Inag Services Ltd | Transport & logistics | 2025 |
| Inayah Couture Limited | Extraterritorial | 2016 |
| Inayah Ltd | Wholesale & retail | 2012 |
| Inbox Recruitment Ltd | Administrative & support | 2019 |