| Inspire Sports Travel Ltd | Administrative & support | 2025 |
| Inspired Bathroom Design and Installation Ltd | Construction | 2008 |
| Inspired Developments Bristol Ltd | Construction | 2023 |
| Inspired Education (East Dunbartonshire) Holdings Limited | Professional & scientific | 2005 |
| Inspired Education (East Dunbartonshire) Limited | Professional & scientific | 2005 |
| Inspired Education (South Lanarkshire) Holdings Limited | Administrative & support | 2005 |
| Inspired Education (South Lanarkshire) PLC | Administrative & support | 2005 |
| Inspired Horizons Limited | Administrative & support | 2008 |
| Inspired Improvements Ltd | Professional & scientific | 2023 |
| Inspired Licensing Limited | Professional & scientific | 2019 |
| Inspired People Ltd | Administrative & support | 2004 |
| Inspired Virtual Solutions Ltd | Administrative & support | 2017 |
| Inspired Web Solutions Ltd | Information & communication | 2016 |
| Inspireware International Limited | Information & communication | 2025 |
| Inspiring Schools Ltd | Education | 2026 |
| Inspiring VET Care Limited | Professional & scientific | 2011 |
| Inspirit Properties Limited | Real estate | 2016 |
| Instabase UK Ltd | Information & communication | 2020 |
| Installation by Design Limited | Wholesale & retail | 1998 |
| Installation Space Limited | Construction | 2003 |
| Instant Lessons Ltd | Education | 2023 |
| Instant Nominees Limited | Professional & scientific | 2007 |
| Instant Recruitment Solutions Limited | Administrative & support | 2013 |
| Instant Signs (Bristol) Limited | Manufacturing | 2011 |
| Instantaction Property Holdings Limited | Real estate | 2001 |
| Instantiate Limited | Information & communication | 2013 |
| Instatruck Ltd | Financial services | 2024 |
| Institute for Financial Wellbeing Limited | Professional & scientific | 2019 |
| Instrolab PC | | 2020 |
| Instructor College UK Ltd | Education | 2022 |
| Instructor Place Limited | Information & communication | 2026 |
| Insula Letting Limited | Real estate | 2021 |
| Insulation Rendering Company Ltd | Construction | 2024 |
| Insurecap Limited | Financial services | 2014 |
| Insurtech Ltd | Other services | 2024 |
| Insync Audio Limited | Information & communication | 2016 |
| Insyzor Consulting Limited | Professional & scientific | 2014 |
| Insyzor Rentals Ltd | Real estate | 2025 |
| Intaj Limited | Arts & recreation | 2022 |
| Intanet South West Ltd | Construction | 2019 |
| Intapart Factors (Bristol) Limited | Wholesale & retail | 1999 |
| Intario LP | | 2016 |
| Intec Telecom Systems Limited | Information & communication | 2000 |
| Intecre Limited | Professional & scientific | 2015 |
| Integra (Wickford) Management Company Limited | Households | 2008 |
| Integra Tech Solutions Ltd | Information & communication | 2025 |
| Integral Construction South West Limited | Construction | 2018 |
| Integral Growth System Ltd | Professional & scientific | 2023 |
| Integral Home Services Ltd | Construction | 2025 |
| Integral Improvements Ltd | Professional & scientific | 2016 |
| Integral Naval Systems Ltd | Professional & scientific | 2025 |
| Integrate Design and Build Ltd | Construction | 2018 |
| Integrated Computer Systems Limited | Information & communication | 2014 |
| Integrated Contracting Services Ltd | Construction | 2018 |
| Integrated Design Partnership Limited | Professional & scientific | 2004 |
| Integrated Domain Solutions Ltd | Professional & scientific | 2024 |
| Integrated Ecological Solutions Limited | Professional & scientific | 2009 |
| Integrated Electrical and Building Services Ltd | Construction | 2025 |
| Integrated Electrical Installations Ltd | Construction | 2025 |
| Integrated Engineering (SW) Ltd. | Households | 2014 |
| Integrated Health Screening Limited | Health & social care | 2007 |
| Integrated Natural Healthcare Ltd | Health & social care | 2017 |
| Integrated Pest Management Limited | Administrative & support | 2003 |
| Integrated Project Controls Ltd | Professional & scientific | 2012 |
| Integrated Systems Engineering Ltd | Professional & scientific | 2024 |
| Integrated Works Ltd | Health & social care | 2020 |
| Integratedtek Ltd | Professional & scientific | 2025 |
| Integration Expertise Ltd | Information & communication | 2018 |
| Integrative Saturday School | Education | 2011 |
| Integrator Ltd | Professional & scientific | 2026 |
| Integris Composites UK Ltd | Professional & scientific | 2000 |
| Integrity Housing Ltd | Real estate | 2007 |
| Integrity Hybrid Auto Group Ltd | Wholesale & retail | 2025 |
| Integrity Legal Solutions Limited | Professional & scientific | 2006 |
| Integrium Ltd | Information & communication | 2014 |
| Integro Construction Software Limited | Information & communication | 2013 |
| Integro Management Limited | Administrative & support | 2025 |
| Intellect Limited | Information & communication | 1984 |
| Intellectra Solutions Ltd | Construction | 2025 |
| Intelli Tune Limited | Wholesale & retail | 2024 |
| Intellico Care Limited | Administrative & support | 2020 |
| Intellico Limited | Wholesale & retail | 2020 |
| Intelligent Autonomy Ltd | Extraterritorial | 2018 |
| Intelligent Business Decisions Ltd | Information & communication | 2013 |
| Intelligent Commercial Services Limited | Real estate | 2014 |
| Intelligent Consulting (Bristol) Limited | Administrative & support | 2007 |
| Intelligent Data Advisory Limited | Professional & scientific | 2022 |
| Intelligent Dimensions Limited | Information & communication | 2004 |
| Intelligent Global Solutions Limited | Information & communication | 2014 |
| Intelligent Project Solutions Limited | Professional & scientific | 2018 |
| Intelligent Resource Limited | Administrative & support | 1979 |
| Intelligenti Limited | Information & communication | 2008 |
| Intellium AI Ltd | Information & communication | 2017 |
| Intellium Ltd | Professional & scientific | 2018 |
| Intent Mobility Group Ltd | Wholesale & retail | 2024 |
| Intequal Limited | Extraterritorial | 2017 |
| Interaction Learning and Development Limited | Professional & scientific | 1995 |
| Interaction Trustee Limited | Professional & scientific | 2015 |
| Interbusiness Consulting Limited | Professional & scientific | 2007 |
| Intercede Sustainability Limited | Professional & scientific | 2024 |