| Ingram Bros Restaurant Co Ltd | Hospitality | 2017 |
| Ingram Consultancy Services Ltd | Professional & scientific | 2024 |
| Inhousetech Ltd | Information & communication | 2026 |
| Inicio Clothing Ltd | Wholesale & retail | 2025 |
| Initiative Logistics Ltd | Transport & logistics | 2013 |
| INK Realms by Gabriela Ltd | Other services | 2024 |
| INK Solutions Group Ltd | Professional & scientific | 2024 |
| Inka Sports Limited | Administrative & support | 2017 |
| Inkjet Solutions Group Ltd | Manufacturing | 2021 |
| Inko Properties Ltd | Construction | 2021 |
| Inkphoria Ltd | Construction | 2023 |
| Inksanity Tattoo Studio Ltd | Other services | 2021 |
| Inland Property Services Ltd | Construction | 2020 |
| Inmarsys Limited | Professional & scientific | 2020 |
| Inmat | Education | 2016 |
| Inn Control Hospitality Accountants Limited | Professional & scientific | 2021 |
| Innautosolutions Ltd | Wholesale & retail | 2025 |
| Inner Balance Therapy Services Limited | Health & social care | 2023 |
| Inner Search Psychotherapy and Counselling Ltd | Other services | 2015 |
| Innergate UK Ltd | Education | 2022 |
| Innocent Services Limited | Health & social care | 2022 |
| Innophyte Consulting Ltd | Professional & scientific | 2023 |
| Innoprinter (UK) Ltd | Manufacturing | 2017 |
| Innosocial Solutions Ltd | Professional & scientific | 2026 |
| Innounity Group Ltd | Professional & scientific | 2025 |
| Innov@Te UK Limited | Transport & logistics | 2008 |
| Innova Beauty Ltd | Professional & scientific | 2024 |
| Innova Technology Services Limited | Wholesale & retail | 2016 |
| Innovate Don’T Imitate Limited Liability Partnership | | 2025 |
| Innovate Marketing Solutions Ltd | Wholesale & retail | 2025 |
| Innovate Recycle Ltd | Manufacturing | 2018 |
| Innovation Beauty Ltd | Other services | 2016 |
| Innovation Security Systems Limited | Administrative & support | 2016 |
| Innovative Office & Domestic Cleaning Services Ltd | Administrative & support | 2026 |
| Innovative Partners (Consulting) Ltd | Professional & scientific | 2018 |
| Innovit Holdings Limited | Financial services | 2020 |
| Innsite Property Ltd | Real estate | 2021 |
| Innsite UK (Holdings) Limited | Financial services | 2025 |
| Inout Limited | Administrative & support | 2025 |
| Inoventive Services Limited | Information & communication | 2017 |
| Inox Interiors Limited | Construction | 2021 |
| Inox Ventilation Ltd | Manufacturing | 2025 |
| Inpulze Electrical Ltd | Construction | 2019 |
| Inpulze Exline Ltd | Construction | 2023 |
| Inpulze Group Ltd | Construction | 2023 |
| Inri Construction Ltd | Construction | 2020 |
| Inside Ground Ltd | Hospitality | 2016 |
| Inside Realtime Ltd | Professional & scientific | 2023 |
| Inside Travel Limited | Professional & scientific | 2010 |
| Insig Property Ltd | Real estate | 2024 |
| Insight Aviation Management Ltd | Professional & scientific | 2022 |
| Insight Forensic Psychology Service Ltd | Professional & scientific | 2012 |
| Insight Pipeline Ltd | Information & communication | 2026 |
| Insightshare Ltd | Information & communication | 1999 |
| Insignia Lift Consultancy Limited | Professional & scientific | 2011 |
| Insisys Developments Limited | Construction | 2018 |
| Insisys Developments Two Limited | Construction | 2023 |
| Insite Accounting & Management Services Limited | Professional & scientific | 2017 |
| Insite Accounting Ltd | Professional & scientific | 2022 |
| Insite Public Practice Recruitment Limited | Other services | 2017 |
| Inspace Construction Group Ltd | Construction | 2014 |
| Inspect Roofing Consultants Ltd | Construction | 2024 |
| Inspiration Radio Ltd. | Information & communication | 2004 |
| Inspirations (Broughton) Management Company Limited | Households | 2010 |
| Inspire Care 24/7 Ltd | Health & social care | 2018 |
| Inspire Design and Build (Northampton) Limited | Construction | 2019 |
| Inspire Group Assets Ltd | Real estate | 2021 |
| Inspire Group Holdings Limited | Financial services | 2025 |
| Inspire Office Technology Ltd | Administrative & support | 2022 |
| INSPIRE4U Ltd | Wholesale & retail | 2019 |
| Inspired by Culture Limited | Wholesale & retail | 2024 |
| Inspired Events Management Limited | Administrative & support | 2006 |
| Inspired Generation Club CIC | Information & communication | 2025 |
| Inspiredstudio-Academy Ltd | Other services | 2022 |
| Inspires Impact Ltd | Information & communication | 2025 |
| Install Carpet B.B.C. Ltd | Construction | 2026 |
| Installation Control Services Ltd | Manufacturing | 2012 |
| Installation Services and Logistics Limited | Construction | 2011 |
| Installations for Business Limited | Information & communication | 2019 |
| Installog Limited | Administrative & support | 2014 |
| Instalogistics Ltd | Transport & logistics | 2023 |
| Instancesecurity Limited | Administrative & support | 2025 |
| Instant Brickwork Company Ltd | Administrative & support | 2019 |
| Instigators Limited | Other services | 1994 |
| Institute of Corrosion | Other services | 1976 |
| Institute of Wastes Management | Professional & scientific | 1928 |
| Instructor Nathan Limited | Education | 2025 |
| Insurably Ltd | Financial services | 2024 |
| Intaero Systems Ltd | Professional & scientific | 2024 |
| Intake Motors Ltd | Wholesale & retail | 2021 |
| Intamarca LLP | | 2010 |
| Intangible Capital Group Ltd | Financial services | 2026 |
| Intass Logistic Ltd | Transport & logistics | 2023 |
| Intec Ltd | Administrative & support | 2015 |
| Intech Ventures Ltd | Financial services | 2019 |
| Inteck Engineering and Fabrication Limited | Manufacturing | 2009 |
| Integra Care Group Ltd | Health & social care | 2026 |
| Integra Home Care Ltd | Health & social care | 2025 |
| Integra Partners Limited | Administrative & support | 2018 |
| Integra Surveys LLP | | 2025 |