| INFIN8 Construction Ltd | Construction | 2019 |
| INFIN8 Digital Limited | Information & communication | 2019 |
| Infini Tech Ltd | Construction | 2021 |
| Infiniti Fitness Gym Limited | Arts & recreation | 2015 |
| Infinity Defence Limited | Professional & scientific | 2023 |
| Infoark Limited | Professional & scientific | 2025 |
| Infocom Training Systems Limited | Manufacturing | 1990 |
| Infonology Ltd | Other services | 2015 |
| Informed Assessment Limited | Professional & scientific | 2002 |
| Informed Limited | Information & communication | 2025 |
| Infrasearch Limited | Administrative & support | 2017 |
| Infrint.Com Limited | Professional & scientific | 2021 |
| Ingestre Limited | Professional & scientific | 2018 |
| Inglewood Management Company Limited | Real estate | 1983 |
| Inguz Consulting Limited | Professional & scientific | 2025 |
| Inhale Capital (SPV1) Limited | Financial services | 2025 |
| Inhale Capital (SPV2) Limited | Financial services | 2025 |
| Inhale Capital (SPV3) Limited | Financial services | 2025 |
| Inhale Capital Limited | Financial services | 2024 |
| Inherent Laboratories Ltd | Information & communication | 2026 |
| Inishmore Ltd | Real estate | 2024 |
| Inivis Consulting Limited | Administrative & support | 2017 |
| Innately Consulting Ltd | Arts & recreation | 2022 |
| Innately Halal Limited | Wholesale & retail | 2026 |
| Inndura Therapeutics (UK) Limited | Professional & scientific | 2022 |
| Innerworks Technology Limited | Information & communication | 2020 |
| Innit Social Limited | Information & communication | 2025 |
| Innova Wellington Ltd | Information & communication | 2025 |
| Innovany Limited | Information & communication | 2021 |
| Innovative Doctors PVT. Limited | Health & social care | 2023 |
| Innovatus Advertising Ltd | Professional & scientific | 2022 |
| Innovia Commercial Management Limited | Professional & scientific | 2022 |
| Inofab UK Limited | Financial services | 2026 |
| Inovex Technologies Limited | Information & communication | 2026 |
| Inrix Holdings UK Ltd | Financial services | 2011 |
| Inrix Media Ltd | Information & communication | 1995 |
| Inrix UK Ltd. | Other services | 1996 |
| Inside Engineering Limited | Professional & scientific | 2025 |
| Insight (NW) Ltd | Professional & scientific | 2006 |
| Insight Clinical Psychology Ltd | Health & social care | 2024 |
| Insight Counsellor Training Ltd | Education | 2025 |
| Insight PS Limited | Construction | 2025 |
| Insightful Data Analytics Limited | Information & communication | 2023 |
| Inskin Group Ltd | Other services | 2015 |
| Insolvex Limited | Financial services | 2025 |
| Insource Talent Limited | Other services | 2015 |
| Inspection Services Direct Limited | Professional & scientific | 2012 |
| Inspera UK Ltd | Information & communication | 2020 |
| Inspire Bidco Limited | Financial services | 2024 |
| Inspire ME Ltd | Information & communication | 2020 |
| Inspired Business Enterprises Limited | Administrative & support | 2014 |
| Inspired Copy Ltd | Professional & scientific | 2020 |
| Inspired Home Solutions by Voss Ltd | Construction | 2024 |
| Inspiretoachieve Partners Ltd | Professional & scientific | 2023 |
| Inspirita Limited | Information & communication | 1999 |
| Inspiro Exterior Cleaning Ltd | Administrative & support | 2026 |
| Instep Podiatry Ltd | Health & social care | 2010 |
| Instrument Engineering Site Solutions Limited | Professional & scientific | 2025 |
| Insurance Claims Centre UK Limited | Financial services | 2000 |
| Integenx Limited | Administrative & support | 2010 |
| Integral Fusion Ltd | Wholesale & retail | 2022 |
| Integrate (Europe) Ltd | Information & communication | 2012 |
| Integrated Handheld Solutions Limited | Information & communication | 2002 |
| Integrion Consulting Limited | Professional & scientific | 2024 |
| Integrity Sentinel Ltd | Information & communication | 2026 |
| Intel Beacon Ltd | Professional & scientific | 2024 |
| Intelda Ltd | Information & communication | 2021 |
| Intellidev IT Consultancy Ltd | Information & communication | 2016 |
| Intelligence Tax & Accountancy Ltd | Professional & scientific | 2013 |
| Intelligence Wealth Management Ltd | Financial services | 2013 |
| Intelligent Electrical Installations Limited | Wholesale & retail | 2007 |
| Intelligent Tax Solutions Limited | Professional & scientific | 2026 |
| Intellista Consulting Limited | Professional & scientific | 2025 |
| Intention IT Limited | Professional & scientific | 2018 |
| Interactive Media UX Limited | Professional & scientific | 2013 |
| Interbrook International Limited | Administrative & support | 2017 |
| Intercel Ltd | Manufacturing | 2005 |
| Internap Network Services U.K. Limited | Information & communication | 1999 |
| International Entrepreneurs Association | Education | 2004 |
| International FIN Crime Prevention Advisory Limited | Professional & scientific | 2026 |
| International Inner Wheel | Other services | 2010 |
| International Logistics Consulting Ltd | Administrative & support | 2025 |
| International Procurement Specialists Limited | Wholesale & retail | 2002 |
| Internorth Developments Limited | Real estate | 1980 |
| Interpayment Services Limited | Other services | 1987 |
| Interpower Limited | Construction | 1997 |
| Interrobang Productions Limited | Information & communication | 2012 |
| Intoplaces Ltd | Professional & scientific | 2019 |
| Intralot Holdings UK Ltd | Financial services | 2025 |
| Intraventure Limited | Information & communication | 2001 |
| Intrinsic Group Services Limited | Administrative & support | 2023 |
| Introx Assets Ltd | Professional & scientific | 2024 |
| Intrépido Limited | Professional & scientific | 2024 |
| Intuilective Technologies Limited | Information & communication | 2025 |
| Invest Property Group Ltd | Real estate | 2025 |
| Investment Holdings (Manchester) Limited | Real estate | 2011 |
| Investmint Limited | Financial services | 2022 |
| Investor Connect Limited | Financial services | 2015 |
| Investy Mcvestface Ltd | Other services | 2026 |
| Invictus Communications Ltd | Information & communication | 2016 |