| Inspired Youth Creator's Ltd | Wholesale & retail | 2020 |
| Inspirelec Ltd | Construction | 2015 |
| Inspirexpression CIC | Administrative & support | 2024 |
| Inspiria Care Ltd | Health & social care | 2018 |
| Inspiring Business Integrating Solutions Ltd | Professional & scientific | 2012 |
| Inspiring Care Ltd | Health & social care | 2019 |
| Inspiring Evolution Consultancy Limited | Professional & scientific | 2013 |
| Inspiring Evolution Holding Ltd | Financial services | 2020 |
| Inspiring Evolution Property Ltd | Real estate | 2020 |
| Inspiring Golf Inclusion C.I.C. | Arts & recreation | 2024 |
| Inspiring Learning (Holdings) Limited | Professional & scientific | 2007 |
| Inspiring Learning Limited | Professional & scientific | 2007 |
| Inspiring Maths Education Ltd | Education | 2017 |
| Inspiring Rooms Limited | Real estate | 2022 |
| Inspiring Sisters CIC | Administrative & support | 2023 |
| Inspirit Bartology Ltd. | Education | 2023 |
| Inspirit Vysus Holdings Limited | Financial services | 2020 |
| Insta Delivery Solutions Ltd | Transport & logistics | 2019 |
| Insta Editing Limited | Information & communication | 2021 |
| Instafab and Maintenance Ltd | Manufacturing | 2018 |
| Install Automation Limited | Information & communication | 1999 |
| Install Electrics Ltd | Other services | 2017 |
| Install Plus Ltd | Construction | 2023 |
| Install-A-Floor Limited | Wholesale & retail | 2019 |
| Installa Ltd | Other services | 2018 |
| Installation & Design Systems Ltd | Construction | 2012 |
| Installation Solution Services Ltd | Manufacturing | 2021 |
| Installernet Ltd | Extraterritorial | 2014 |
| Instant Accounting Solutions Ltd | Professional & scientific | 2020 |
| Instant Balmer Ltd | Manufacturing | 2025 |
| Instant Check Ltd | Administrative & support | 2024 |
| Instant Claim Midlands Ltd | Professional & scientific | 2014 |
| Instant Delites Limited | Hospitality | 2024 |
| Instant Family Ltd | Health & social care | 2025 |
| Instant MIX Concrete Ltd | Construction | 2017 |
| Instant Promotion (UK) Ltd | Wholesale & retail | 2008 |
| Instant Solutions (PK) Ltd | Wholesale & retail | 2012 |
| Instant Support Services (ISS) Limited | Administrative & support | 2023 |
| Instareach Ltd | Information & communication | 2022 |
| Instastaff Ltd | Administrative & support | 2023 |
| Instep Plus CIC | Professional & scientific | 2025 |
| Instepz Limited | Education | 2007 |
| Instinct Hardware Limited | Wholesale & retail | 2016 |
| Instinctive Properties Limited | Real estate | 2020 |
| Institut I.W.E.C.A. Limited | Administrative & support | 2009 |
| Institute of Materials Finishing | Professional & scientific | 1951 |
| Instream Energy UK Ltd | Manufacturing | 2017 |
| Instrument Calibration and Testing Limited | Professional & scientific | 2009 |
| Instudents Ltd | Education | 2023 |
| Insu Doors Limited | Manufacturing | 2019 |
| INSUL8 Mids. Limited | Construction | 2012 |
| Insulation & Cladding Services Limited | Construction | 2010 |
| Insulation Contracting Services Limited | Construction | 1992 |
| Insulationk Ltd | Wholesale & retail | 2022 |
| Insurance, Risk & Claims Management Limited | Financial services | 2000 |
| Insure Alert Limited | Information & communication | 2023 |
| Insure Line UK Limited | Financial services | 2005 |
| Insure Right Limited | Extraterritorial | 2019 |
| Insureit UK Ltd | Financial services | 2004 |
| Insync Management Ltd | Construction | 2019 |
| INT Care Solutions Ltd | Health & social care | 2023 |
| INT Cleaning Services Ltd | Administrative & support | 2024 |
| INT Consulting Solutions Ltd | Administrative & support | 2018 |
| INT IT Ltd | Transport & logistics | 2024 |
| INT One Transport Ltd | Transport & logistics | 2024 |
| INT Services Limited | Professional & scientific | 2006 |
| INT+ Limited | Manufacturing | 2018 |
| INT. Automotive Ltd | Professional & scientific | 2023 |
| INT. Handelsagentur Limited | Administrative & support | 2009 |
| INT. Trade Limited | Wholesale & retail | 2023 |
| Intact Group (UK) Ltd | Construction | 2014 |
| Intact UK Birmingham Ltd | Manufacturing | 2018 |
| Intar Surfaces Limited | Administrative & support | 2015 |
| Intefit Limited | Construction | 2020 |
| Integer IT Consulting Ltd | Wholesale & retail | 2011 |
| Integer Resourcing Limited | Professional & scientific | 2011 |
| INTEGR8 Consulting Limited | Information & communication | 2017 |
| Integra Children's Home Limited | Health & social care | 2006 |
| Integra Management Solutions Ltd | Professional & scientific | 2022 |
| Integral Accountants & Business Advisors Ltd | Professional & scientific | 2017 |
| Integral Estates Limited | Real estate | 2018 |
| Integral Resource Management Limited | Professional & scientific | 2012 |
| Integral Tech Services Limited | Information & communication | 2021 |
| Integrale Logistics Multi Services Ltd | Transport & logistics | 2017 |
| Integrasoft International Limited | Information & communication | 2025 |
| Integratables Limited | Administrative & support | 2023 |
| Integrate Consulting Ltd | Information & communication | 2013 |
| Integrated Building Controls Limited | Professional & scientific | 2017 |
| Integrated Cleaning Management Limited | Administrative & support | 1996 |
| Integrated Cleaning Management Support Services Limited | Administrative & support | 2002 |
| Integrated Continuity Solutions Ltd | Professional & scientific | 2013 |
| Integrated Design Techniques Limited | Manufacturing | 1987 |
| Integrated Designs & Associates Limited | Administrative & support | 2008 |
| Integrated Development Advisory Ltd | Financial services | 2026 |
| Integrated Development Alliance Ltd | Financial services | 2026 |
| Integrated Diaspora Services (UK) Limited | Public administration | 2022 |
| Integrated Electrics Limited | Construction | 2026 |
| Integrated Housing Ltd | Real estate | 2026 |
| Integrated Nuclear Group Ltd | Professional & scientific | 2021 |
| Integrated Pain Medicine Ltd | Health & social care | 2026 |