| Insightful Diagnostics Limited | Health & social care | 2023 |
| Insights Media Limited | Information & communication | 2011 |
| Inspace Design Limited | Real estate | 2014 |
| Inspecs Group PLC | Administrative & support | 2019 |
| Inspecs Holdings Limited | Professional & scientific | 2007 |
| Inspecs Limited | Manufacturing | 1988 |
| Inspire Displays Limited | Administrative & support | 2005 |
| Inspire Property Limited | Construction | 2017 |
| Inspired Inns Ltd | Hospitality | 2022 |
| Inspired Literature Ltd | Financial services | 2018 |
| Inspired Market Property Ltd | Real estate | 2025 |
| Inspired Waller Industries Limited | Education | 2021 |
| Inspiring Fundz Limited | Financial services | 2004 |
| Inspoda Limited | Real estate | 2014 |
| Insurance Services (West END) Limited | Real estate | 1966 |
| Integral Engineering Design Ltd | Professional & scientific | 1999 |
| Integral Structural Design Ltd | Professional & scientific | 2009 |
| Integral Test & Quality Engineering Ltd | Information & communication | 2015 |
| Integrated Quality Support Ltd | Professional & scientific | 2017 |
| Integrator Housing Solutions Ltd | Administrative & support | 2006 |
| Integris Health Community Services Limited | Health & social care | 2026 |
| Intelligent Lifecycle Solutions Limited | Manufacturing | 2013 |
| Intelligent Plans and Examinations (IPE) Limited | Professional & scientific | 2016 |
| Intelligent Property (Bath) Limited | Real estate | 2009 |
| Intelligent Trade Network Limited | Extraterritorial | 2013 |
| Intense Experiences Limited | Real estate | 2019 |
| Inter-Tech QED Ltd | Administrative & support | 2010 |
| Interaction Associates Limited | Construction | 1992 |
| Interactive Squared Limited | Information & communication | 2010 |
| Interior Harmony Flooring Limited | Wholesale & retail | 2003 |
| Interiors by Libby Carter Ltd | Professional & scientific | 2019 |
| International Cerebral Palsy Society(The) | Other services | 1976 |
| International Eyewear Limited | Wholesale & retail | 1988 |
| International Magic Group Limited | Arts & recreation | 2017 |
| International Magic Studio Ltd | Arts & recreation | 2022 |
| Interscript Limited | Arts & recreation | 2011 |
| Intobusiness Ltd | Professional & scientific | 2023 |
| Intrinsic Wellness Ltd | Education | 2020 |
| Intybus-Solutions Ltd | Professional & scientific | 2021 |
| Invert Media Ltd | Information & communication | 2026 |
| Inverterre Limited | Information & communication | 2006 |
| Invest Ahead Limited | Education | 2026 |
| IO Loop Limited | Information & communication | 2016 |
| Iomosaic International Limited | Information & communication | 2017 |
| Iowna Gowns Limited | Wholesale & retail | 2020 |
| IP Forensics (GB) Limited | Other services | 2007 |
| Ipfs UK (Bath) Limited | Manufacturing | 2014 |
| Ipgma Ltd | Professional & scientific | 2025 |
| Iprostaid Technologies Ltd | Manufacturing | 2023 |
| IPS Bath Ltd | Administrative & support | 2009 |
| Iqfx Ltd. | Administrative & support | 2017 |
| Ireland Plant Services Ltd. | Construction | 2014 |
| Iremia Technology Limited | Information & communication | 2021 |
| Iris Intelligence Limited | Information & communication | 2007 |
| Iris Public Relations London Ltd | Other services | 2015 |
| Irmantes Pukienes Limited | Health & social care | 2025 |
| Ironbridge House Development Limited | Real estate | 2020 |
| Ironbridge House One Limited | Real estate | 2022 |
| Ironic Coaching and Personal Training Ltd | Arts & recreation | 2025 |
| Isabella House (Bath) Management Ltd | Households | 2023 |
| Isabella Mews Management Company Limited | Real estate | 2022 |
| Isaro Publishing Ltd | Information & communication | 2014 |
| Isg&Co Limited | Transport & logistics | 2024 |
| Isherwood Fine Art Limited | Wholesale & retail | 2003 |
| Isims Limited | Professional & scientific | 2022 |
| Isleworth Services Ltd | Information & communication | 2024 |
| ISM Landscaping Limited | Construction | 2024 |
| Ison Creative Limited | Information & communication | 2007 |
| Isopleth Ltd | Construction | 2014 |
| Issunboshi Ltd | Information & communication | 2026 |
| Istaybath Ltd | Hospitality | 2018 |
| Isus Limited | Real estate | 2008 |
| IT Business Intelligence Solutions Limited | Professional & scientific | 2013 |
| IT Caretaker Limited | Information & communication | 2011 |
| IT Caters Limited | Hospitality | 2019 |
| IT Development Plus Ltd | Real estate | 1997 |
| Itello Limited | Information & communication | 2004 |
| ITS a Wonderful Life Ltd | Other services | 2009 |
| Itura Limited | Health & social care | 2012 |
| IVA Healthcare Ltd | Health & social care | 2022 |
| Ivan Building Solutions Ltd | Construction | 2018 |
| Ivinghoe Ltd | Real estate | 2021 |
| IVV Transport Ltd | Transport & logistics | 2026 |
| IVY and Beam Ltd | Real estate | 2025 |
| IVY Financial Limited | Financial services | 2021 |
| IW Heating & Plumbing Services Limited | Construction | 2008 |
| Izzi Eight Ltd | Real estate | 2020 |
| J & J South Holdings Limited | Financial services | 2020 |
| J @ L Property Ltd | Real estate | 2024 |
| J a R Dixon Ltd | Other services | 2021 |
| J and M Technologies Ltd | Manufacturing | 2021 |
| J B Denture Clinic (Bath) Ltd | Health & social care | 2016 |
| J Brophy Limited | Professional & scientific | 2002 |
| J D Willment Ltd | Construction | 2020 |
| J H Plastering (Bath) Limited | Construction | 2012 |
| J IS for Jaguar Limited | Financial services | 2023 |
| J Leavy Medical Writing Ltd | Professional & scientific | 2020 |
| J M Galik Ltd | Real estate | 2026 |
| J M Hurst Plumbing & Heating Ltd | Construction | 2026 |
| J N Kelly Global Trading Limited | Administrative & support | 2012 |