| Ideas for Life Ltd | Professional & scientific | 2004 |
| Ideasbynet Limited | Professional & scientific | 1999 |
| Ideasinc. Ltd | Professional & scientific | 2015 |
| Idee Solutions Limited | Construction | 2011 |
| Identity Capital Limited | Wholesale & retail | 2020 |
| Identity Merchandise Limited | Administrative & support | 2013 |
| Identity Sunbeds Limited | Other services | 2025 |
| Idetek UK Ltd | Professional & scientific | 2017 |
| IDG Media Limited | Administrative & support | 2003 |
| Idini Limited | Information & communication | 2007 |
| IDK Support 4 YOU Ltd | Other services | 2011 |
| Idle Furniture Limited | Manufacturing | 2026 |
| IDO3D Ltd | Professional & scientific | 2026 |
| Idoctor UK Ltd | Other services | 2019 |
| Idoctor UK Media Ltd | Information & communication | 2025 |
| Idris Food Ltd | Hospitality | 2025 |
| Idris Rahman Productions Limited | Information & communication | 2018 |
| Idsc Group Ltd | Wholesale & retail | 2021 |
| IEC Rail and Metro Engineering Ltd | Manufacturing | 2016 |
| IEE Trans Limited | Transport & logistics | 2025 |
| IEL Consulting Limited | Wholesale & retail | 2021 |
| IFA Group Limited | Professional & scientific | 2018 |
| IFA Metals International Limited | Professional & scientific | 2011 |
| Ifapa Ltd. | Financial services | 2010 |
| IFB Projects Ltd | Construction | 2017 |
| Iffley Club Limited | Hospitality | 2025 |
| Ific | Other services | 1994 |
| Ifoit Ltd | Administrative & support | 2016 |
| IFP Investments Limited | Real estate | 2021 |
| Ifrf Limited | Professional & scientific | 2017 |
| IFS House Ltd | Wholesale & retail | 2024 |
| Ifst (UK) Ltd | Education | 2017 |
| Ifte.Uk Ltd | Professional & scientific | 2023 |
| Iftikhar ALI Ltd | Health & social care | 2026 |
| IG & JB Flooring Limited | Wholesale & retail | 2014 |
| IG Hydraulics and Fabrications Ltd | Manufacturing | 2014 |
| IG Management Ltd. | Real estate | 2014 |
| IG Private Ltd | Hospitality | 2019 |
| Igbo Union South Yorkshire | Education | 2023 |
| Iggly and Co. Ltd | Real estate | 2022 |
| Iggy & Co Ltd | Hospitality | 2025 |
| Igloo Accommodation Limited | Real estate | 2008 |
| Igloo Real Estate Ltd | Real estate | 2019 |
| Iglu Communications Ltd | Information & communication | 2010 |
| IGN Smart Properties Limited | Real estate | 2025 |
| Ignatia Fire Risk Assessment Ltd | Financial services | 2025 |
| Ignian Limited | Professional & scientific | 2017 |
| Ignite Engineering Recruitment Limited | Administrative & support | 2025 |
| Ignite GAS Services Doncaster Limited | Construction | 2016 |
| Ignite REC2REC Ltd | Administrative & support | 2021 |
| Ignite York Ltd | Construction | 2019 |
| Ignition GAS Services Ltd | Construction | 2010 |
| Ignition Search Limited | Information & communication | 2008 |
| Ignivox Consulting Limited | Professional & scientific | 2025 |
| Igor Longinidis Ltd. | Arts & recreation | 2018 |
| IGR Decorators Ltd | Construction | 2022 |
| Igrow Virtual IT Solutions PVT Ltd | Information & communication | 2023 |
| Igvuk Limited | Professional & scientific | 2014 |
| IGW Solutions Limited | Professional & scientific | 2013 |
| IH & a UK Limited | Real estate | 2015 |
| IH Auto Ltd | Wholesale & retail | 2020 |
| IH Elite Systems Ltd | Wholesale & retail | 2025 |
| IH Exchange Limited | Financial services | 2026 |
| Ihmg Ltd | Hospitality | 2020 |
| IIB Ltd | Administrative & support | 2024 |
| IID UK Ltd | Health & social care | 2025 |
| IJ Food Ltd | Hospitality | 2022 |
| IJB Investments Limited | Real estate | 2017 |
| IJB Property Holdings Ltd | Real estate | 2019 |
| Ijemmy Better Life Ltd | Other services | 2026 |
| IJH Auto Limited | Administrative & support | 2025 |
| IJL Property’S Ltd | Real estate | 2025 |
| IJW Lettings Ltd | Real estate | 2026 |
| IK + Softy Touch Ltd | Wholesale & retail | 2024 |
| IK Contracts Ltd | Other services | 2018 |
| IK Engineering Services Limited | Hospitality | 2007 |
| IK Medical Ltd | Health & social care | 2019 |
| IK Publicity Ltd | Professional & scientific | 2017 |
| IK UK Trading Ltd | Hospitality | 2025 |
| Ikhlas Properties & Investment Ltd | Real estate | 2021 |
| Ikonika Consulting Limited | Professional & scientific | 2018 |
| Ikonografik Design Ltd | Professional & scientific | 2005 |
| IKR Holdings Ltd | Real estate | 2018 |
| IKR Sheff Ltd | Professional & scientific | 2020 |
| Ikraworks Limited | Hospitality | 2021 |
| IKT Logistics Ltd | Transport & logistics | 2024 |
| IL Forno Bakery (HAA) Limited | Hospitality | 2021 |
| Ilac Consultancy Services Ltd | Construction | 2017 |
| ILC Marketing Services Limited | Information & communication | 2014 |
| ILET4YOU Limited | Real estate | 2016 |
| Ilex Live Ltd | Construction | 2020 |
| Ilie & Mario Ltd | Transport & logistics | 2017 |
| Ilitech Consulting Ltd | Information & communication | 2025 |
| Illbur Limited | Real estate | 2019 |
| Illuminaries Limited | Information & communication | 1991 |
| Illusion Media Group Limited | Information & communication | 2025 |
| Illustrious Fitness Limited | Arts & recreation | 2025 |
| ILP Trade Limited | Arts & recreation | 2024 |
| Ilproperties Ltd | Administrative & support | 2016 |
| Ilux Lighting Ltd | Manufacturing | 2002 |