| Ideal Property (Cheshire) Ltd | Real estate | 2023 |
| Ifridgeapp UK Limited | Information & communication | 2025 |
| Igbo Union Stoke-On-Trent Ltd | Education | 2025 |
| IIB Trading Ltd. | Professional & scientific | 2018 |
| Iluvlive Limited | Arts & recreation | 2014 |
| Image Tyres Limited | Wholesale & retail | 2014 |
| Imageworks North East Limited | Manufacturing | 2011 |
| Imdr Invest Limited | Real estate | 2025 |
| IMG Newcastle Ltd | Other services | 2023 |
| IMM DEE Limited | Hospitality | 2026 |
| Impact Architecture and Engineering Ltd | Professional & scientific | 2025 |
| Impact Law Limited | Professional & scientific | 2023 |
| Impact Productions Limited | Administrative & support | 1998 |
| Imperial Car and Commercial Ltd | Wholesale & retail | 2022 |
| Imperial City Takeaway Limited | Hospitality | 2023 |
| Impulse Embedded Limited | Manufacturing | 1993 |
| Imrie Engineering Ltd | Manufacturing | 2003 |
| IN N OAT Ltd | Hospitality | 2026 |
| IN the Dog House Doggy Day Care Limited | Other services | 2023 |
| In-Tuition Holistic Education Ltd | Education | 2015 |
| Incap Electronics UK Ltd | Manufacturing | 1996 |
| Incap Holdings UK Ltd | Manufacturing | 2012 |
| Inclusive Adventures CIC | Health & social care | 2024 |
| India Vegan Properties Limited | Real estate | 2021 |
| Indigo Awnings Limited | Other services | 2008 |
| Indigo Law Limited | Extraterritorial | 2011 |
| Indoor Repair Pros Ltd | Construction | 2026 |
| Indulgence Desserts Newcastle Ltd | Hospitality | 2025 |
| Indulgence Retail Group Limited | Wholesale & retail | 2022 |
| Industrial Auction News Ltd | Information & communication | 2020 |
| Infinite Mind Consults Ltd | Administrative & support | 2024 |
| Infinity Aero Ltd | Transport & logistics | 2021 |
| Infrevival Ltd | Professional & scientific | 2025 |
| Ingenium Europe Limited | Professional & scientific | 2010 |
| INK R Nation Limited | Other services | 2023 |
| Inner Bay Consulting Ltd. | Information & communication | 1996 |
| Inniu Ltd | Administrative & support | 2011 |
| Innovate R&D Ltd | Information & communication | 2024 |
| Innovation Central Limited | Professional & scientific | 2011 |
| Innovex Global Executive Search Limited | Administrative & support | 2020 |
| Innovex Technologies Ltd | Information & communication | 2018 |
| Inovocan Ltd | Financial services | 2025 |
| Inoxium Ltd | Wholesale & retail | 2023 |
| Inpart Holdings Limited | Financial services | 2024 |
| Inpart Limited | Hospitality | 1992 |
| Inspire Learning Consultancy Ltd | Professional & scientific | 2012 |
| Institute for Signal Trust Ltd | Information & communication | 2025 |
| Insulation for Houses Ltd | Construction | 2022 |
| Integrated Project Delivery LLP | | 2016 |
| Integrated Strategy Consulting Limited | Professional & scientific | 2022 |
| Intellmovique Ltd | Information & communication | 2024 |
| Intercity PH Ltd | Transport & logistics | 2026 |
| Interdri UK Ltd | Extraterritorial | 2008 |
| Intermobility Private Hire Ltd | Transport & logistics | 2023 |
| International Financial Reporting Standards Foundation | | 2023 |
| International Living Limited | Hospitality | 2018 |
| International Space Station (ISS) Prop CO1 Limited | Real estate | 2026 |
| Interoperable Health Ltd | Information & communication | 2026 |
| Interval Labs Ltd | Professional & scientific | 2026 |
| Intium Construction Limited | Construction | 2014 |
| Intium Homes Limited | Construction | 2017 |
| Into the Fire Ltd | Arts & recreation | 2023 |
| Invespire Ltd | Real estate | 2024 |
| IPD Energy Ltd | Information & communication | 2019 |
| IPD Limited | Professional & scientific | 2017 |
| Iphiesmith Brand Limited | Manufacturing | 2025 |
| IPS Ceramics Limited | Manufacturing | 2009 |
| Ireland's Icecream Belfast Ltd | Hospitality | 2018 |
| Iresolve Ltd | Professional & scientific | 2014 |
| Iris Sale Property Ltd | Real estate | 2024 |
| IRM Engineering Ltd | Professional & scientific | 2023 |
| IRM Property Ltd | Real estate | 2026 |
| Ironmasters Solutions Limited | Administrative & support | 2025 |
| Isiah Ltd | Health & social care | 2015 |
| ISP Trans Ltd | Transport & logistics | 2019 |
| Itsupport-Ni Ltd | Information & communication | 2019 |
| Ixsia Construction Ltd | Construction | 2014 |
| Ixsia Group Limited | Construction | 2020 |
| J & B Properties (Staffordshire) Limited | Real estate | 2010 |
| J & J Designs (Staffordshire) Ltd | Wholesale & retail | 2008 |
| J & J GAS Solutions Ltd | Construction | 2022 |
| J & K Mechanical Ltd | Construction | 2019 |
| J B Plumbing & Heating (Staffs) Ltd | Construction | 2013 |
| J COX Data Science Ltd | Information & communication | 2024 |
| J D Brickwork & Landscaping Ltd | Construction | 2024 |
| J Downes Ltd | Education | 2022 |
| J E Edmans Group Limited | Financial services | 2026 |
| J H Elec Limited | Construction | 2013 |
| J J Sons & Co Ltd | Wholesale & retail | 2019 |
| J K Goche Services Ltd | Administrative & support | 2024 |
| J K Shergill Limited | Health & social care | 2025 |
| J M Pala Limited | Wholesale & retail | 2022 |
| J R Beech Ltd | Real estate | 2024 |
| J Stephens Consulting Ltd | Information & communication | 2025 |
| J W Cantrell Haulage Contractors Limited | Transport & logistics | 2015 |
| J&E Mobile Trading Ltd | Hospitality | 2017 |
| J. W. Walker Limited | Wholesale & retail | 1992 |
| J.A.Knight(Coppice)Limited | Real estate | 1963 |
| J.Blandford Ltd | Construction | 2016 |
| J.U.G. Limited | Hospitality | 2013 |