| Inspired Works Limited | Construction | 2024 |
| Inspiring Greatness | Education | 2011 |
| Inspiring Leaders Limited | Education | 2012 |
| Inspiring People Solutions Ltd | Professional & scientific | 2011 |
| Insta Accountants Limited | Professional & scientific | 2019 |
| Insta Hair Ltd | Other services | 2021 |
| Insta Waste Solutions Limited | Water & waste | 2010 |
| Instamart 1 Limited | Wholesale & retail | 2025 |
| Instant Install Limited | Construction | 2018 |
| Instant Storage Limited | Transport & logistics | 2002 |
| Instaplants Ltd | Real estate | 2020 |
| Instatherm Combustion Services Limited | Construction | 1989 |
| Instinct HR Ltd. | Professional & scientific | 2020 |
| Instinct Laboratory Holdings Limited | Professional & scientific | 2012 |
| Instinct Laboratory Limited | Professional & scientific | 2006 |
| Instride Limited | Professional & scientific | 2020 |
| Instrument Repair Service (Nottingham) Limited | Manufacturing | 2021 |
| Instrutech Engineering Ltd | Professional & scientific | 2013 |
| Insulation Energy Solutions Limited | Manufacturing | 2022 |
| Insulation One Ltd | Manufacturing | 2021 |
| Insulation Station Ltd | Wholesale & retail | 2019 |
| Insurli Ltd | Information & communication | 2026 |
| Insync Training & Development Ltd | Professional & scientific | 2025 |
| INT & T Services Ltd | Professional & scientific | 2026 |
| Int-Ext Building Ltd | Construction | 2015 |
| Intagear Limited | Wholesale & retail | 2025 |
| Intalan Ltd. | Information & communication | 2002 |
| Intaspec Holdings Limited | Financial services | 2016 |
| Integra Legal Limited | Professional & scientific | 2010 |
| Integra Products Holdings Limited | Administrative & support | 2000 |
| Integra Products Limited | Manufacturing | 2007 |
| Integradec Ltd | Construction | 2025 |
| Integral Audio Solutions Ltd | Information & communication | 2023 |
| Integral Impact CIC | Education | 2026 |
| Integral Property Management (Nottingham) Ltd | Real estate | 2022 |
| Integral Property Relocation Ltd | Hospitality | 2023 |
| Integral Safety Management Limited | Professional & scientific | 2008 |
| Integral Social Care Ltd | Health & social care | 2023 |
| Integral Wealth Management Limited | Real estate | 2013 |
| Integralware Ltd | Professional & scientific | 2008 |
| Integrated Care Service Provisions Ltd. | Professional & scientific | 2017 |
| Integrated Care Solutions (East Kent) Holdings Limited | Public administration | 2003 |
| Integrated Care Solutions (East Kent) Limited | Administrative & support | 2003 |
| Integrated Care Solutions (Shropshire) Holdings Limited | Public administration | 2005 |
| Integrated Care Solutions (Shropshire) Limited | Public administration | 2005 |
| Integrated Communication Services (Holdings) Limited | Financial services | 2012 |
| Integrated Communication Services Limited | Information & communication | 2004 |
| Integrated Duct Services Limited | Construction | 2013 |
| Integrated Electrical Systems Limited | Construction | 2006 |
| Integrated Investments Limited | Real estate | 1964 |
| Integrated Management Solutions (Global) Limited | Professional & scientific | 2008 |
| Integrated Medical Consultancy Limited | Health & social care | 2025 |
| Integrated Planning Services Ltd | Professional & scientific | 2023 |
| Integrated Security Group Limited | Information & communication | 2022 |
| Integrated Therapy and Education Specialist Ltd. | Education | 2015 |
| Integrated Transport Planning Limited | Professional & scientific | 1997 |
| Integrative Analytics Limited | Professional & scientific | 2009 |
| Integris Finance Ltd | Real estate | 2022 |
| Integrity Business Holdings Limited | Financial services | 2022 |
| Integrity Property Ventures Limited | Real estate | 2022 |
| Integrity Recruitment Solutions Limited | Administrative & support | 2019 |
| Intel Cars Ltd | Transport & logistics | 2023 |
| Intelepos Ltd | Information & communication | 2018 |
| Intelicle Ltd | Information & communication | 2016 |
| Inteligen Limited | Information & communication | 2015 |
| Intellecptl Limited | Information & communication | 2014 |
| Intellect Solutions Limited | Information & communication | 2021 |
| Intellectual Concepts Ltd | Information & communication | 2025 |
| Intellectus Strategies CIC | Information & communication | 2024 |
| Intelligent Decisioning Holdings Ltd | Financial services | 2020 |
| Intelligent Decisioning Ltd | Information & communication | 1997 |
| Intelligent Design Innovations Limited | Professional & scientific | 2014 |
| Intelligent Electrical Ltd | Construction | 2016 |
| Intelligent Engineering (Structural) Ltd | Professional & scientific | 2020 |
| Intelligent Money Advisor Support Limited | Other services | 2023 |
| Intelligent Money Private Clients Limited | Administrative & support | 2007 |
| Intelligent Money Trustees Limited | Other services | 2015 |
| Intelligent Play Ltd | Arts & recreation | 2017 |
| Intelligent Swim Solutions Ltd | Arts & recreation | 2016 |
| Intelligentia Global Limited | Professional & scientific | 2023 |
| Intelligenza Limited | Information & communication | 2009 |
| Intellure Ltd | Information & communication | 2020 |
| Intentia Consulting Ltd | Professional & scientific | 2026 |
| Inter City Environmental Consultants Limited | Water & waste | 2010 |
| Inter City Environmental Services Ltd | Water & waste | 2025 |
| Inter Recruitment Limited | Administrative & support | 2021 |
| Interaction Film Ltd | Information & communication | 2009 |
| Interactive HR Manager Ltd | Professional & scientific | 2012 |
| Interactive View Limited | Information & communication | 2016 |
| Interbase Software Limited | Information & communication | 2000 |
| Interbat Ltd | Wholesale & retail | 2022 |
| Interchange Residences Ltd | Real estate | 2026 |
| Intercontinental Cables Limited | Wholesale & retail | 1992 |
| Intercontinental Trading Services Ltd | Information & communication | 2015 |
| Interesting Concept Limited | Real estate | 2004 |
| Interflon Lubricants Limited | Wholesale & retail | 2024 |
| Intergrand UK Limited | Wholesale & retail | 2008 |
| Interim Logistics Project Management Ltd | Transport & logistics | 2017 |
| Interior Design Guru Ltd | Construction | 2023 |
| Interkonsult Limited | Extraterritorial | 1996 |