| Inspire by Design Group Limited | Manufacturing | 2025 |
| Inspire Footballl Academy CIC | Education | 2024 |
| Inspire HR Services Ltd | Administrative & support | 2024 |
| Inspire Independence Ltd | Public administration | 2025 |
| Inspire Sheffield Ltd | Administrative & support | 2020 |
| Inspire Well Cleaning Services Ltd | Administrative & support | 2026 |
| Inspired by Travel Ltd | Administrative & support | 2020 |
| Inspired Development Solutions Ltd | Real estate | 2005 |
| Inspired Gastronomy Group Ltd | Hospitality | 2026 |
| Inspired Home Care Limited | Health & social care | 2022 |
| Inspired Leisure & Entertainment Limited | Real estate | 2009 |
| Inspired Pharma Training Limited | Administrative & support | 2010 |
| Inspiring Community Homes Ltd | Other services | 2023 |
| Inspirited Futures CIC | Households | 2023 |
| Instafix Glazing Limited | Construction | 2020 |
| Instafix Rentals and Renovations Ltd | Real estate | 2025 |
| Instagold Ltd | Manufacturing | 2025 |
| Installation Design Service Limited | Professional & scientific | 1992 |
| Installation Technical Services Ltd | Manufacturing | 2022 |
| Instant Electronics Services Leeds Limited | Other services | 2007 |
| Instant Print Limited | Manufacturing | 2003 |
| Instant Rent Solution Ltd | Real estate | 2025 |
| Instant Solution Property Ltd | Real estate | 2024 |
| Instant Tools Ltd | Wholesale & retail | 2020 |
| Instant Travel Limited | Other services | 2022 |
| Instarad Limited | Health & social care | 2024 |
| Instasend Ltd | Information & communication | 2026 |
| Instech Global Ltd | Professional & scientific | 2026 |
| Institute of Buildings and Health Limited | Information & communication | 2013 |
| Institute of Specialist Surveyors and Engineers | Professional & scientific | 1990 |
| Instoneville Limited | Information & communication | 2019 |
| INSTRUCT3D Limited | Information & communication | 2024 |
| Insub Audio Ltd | Administrative & support | 2022 |
| Insul Hub Contracting Ltd | Construction | 2019 |
| Insul Hub Limited | Wholesale & retail | 2017 |
| Insulation & Machining Services Limited | Extraterritorial | 1993 |
| Insulation Direct Limited | Other services | 2016 |
| Insulslab Limited | Extraterritorial | 2002 |
| Insure Protect Limited | Financial services | 2012 |
| Insured Health Ltd | Financial services | 2015 |
| Insynch Energy Alliance Company Limited | Wholesale & retail | 2017 |
| Insynch Energy Services Limited | Manufacturing | 2014 |
| INT Consulting Ltd | Construction | 2018 |
| INT Marius Limited | Information & communication | 2019 |
| Inta Computer Trading Ltd. | Transport & logistics | 2002 |
| Intake 100 Ltd | Hospitality | 2025 |
| Intake Electrical & Mechanical Limited | Construction | 2006 |
| Intake Electrical Services Ltd | Construction | 2020 |
| Intake Motors Global Ltd | Water & waste | 2025 |
| Intake Pre-School | Education | 2004 |
| Intecloud Global Ltd | Wholesale & retail | 2025 |
| Integra (Mcvey) Limited | Professional & scientific | 2001 |
| Integra Business Solutions Limited | Administrative & support | 2003 |
| Integra Creative Solutions Limited | Professional & scientific | 2011 |
| Integra Lithium LRJ LLP | | 2023 |
| Integra Lithium Resources LLP | | 2021 |
| Integra Software Design Limited | Information & communication | 2002 |
| Integral Coaching UK Limited | Education | 2012 |
| Integral Transport Limited | Education | 2024 |
| Integrated Applications Limited | Information & communication | 2000 |
| Integrated Flexi Solutions Ltd | Water & waste | 2016 |
| Integrated Hybrid Systems Limited | Administrative & support | 2025 |
| Integrated Mechanical Electrical Contractors Ltd | Manufacturing | 2013 |
| Integrated Practice Services (IPS) Limited | Real estate | 2024 |
| Integrated Research Solutions Global Limited | Professional & scientific | 2021 |
| Integrating & Inspiring Communities CIC | Education | 2025 |
| Integrit Integrated Solutions Ltd | Information & communication | 2025 |
| Integritis Foundation CIC | Education | 2025 |
| Intelesis Limited | Information & communication | 2004 |
| Intelipod Ltd | Administrative & support | 2020 |
| Intellectual Bunch Ltd | Information & communication | 2014 |
| Intellectual Capital Sispa UK Limited | Professional & scientific | 2024 |
| Intelliam AI PLC | Information & communication | 2023 |
| Intelligen Linear Generators (Group) Limited | Financial services | 2025 |
| Intelligent Admission Services Limited | Professional & scientific | 2014 |
| Intelligent AI Solutions Ltd | Information & communication | 2023 |
| Intelligent Cooling Solutions Ltd | Construction | 2017 |
| Intelligent Drilling Tools Limited | Administrative & support | 2008 |
| Intelligent Energy Saving Company Holdings Limited | Financial services | 2015 |
| Intelligent Energy Saving Company Limited | Manufacturing | 2015 |
| Intelligent Haulage and Logistics Ltd | Transport & logistics | 2018 |
| Intelligent Mortgage Finance Limited | Financial services | 2008 |
| Intelligent Protect and Clean Limited | Administrative & support | 2019 |
| Intelligent Protection Management Group Limited | Administrative & support | 2006 |
| Intelligration Limited | Information & communication | 2014 |
| Intelliml Solutions Limited | Professional & scientific | 2025 |
| Intellisprings Limited | Information & communication | 2025 |
| Intellivet Limited | Professional & scientific | 2024 |
| Intems Ltd | Construction | 2020 |
| Intensity Attire Ltd | Extraterritorial | 2021 |
| Intensity Ltd | Arts & recreation | 2017 |
| Intention Pictures Ltd | Information & communication | 2010 |
| Inter City Developer Ltd | Real estate | 2024 |
| Inter Holdco Limited | Real estate | 2024 |
| Inter Propco Limited | Real estate | 2024 |
| Inter VIP Ltd | Information & communication | 2011 |
| Interactive Communications Ltd | Information & communication | 2004 |
| Intercare Services Direct Limited | Health & social care | 2007 |
| Intercast UK Limited | Administrative & support | 2001 |
| Interchange Sandwich Cafe Limited | Hospitality | 2025 |