| Image Painting Contractors Limited | Construction | 2016 |
| Image Sign Systems Ltd | Professional & scientific | 2015 |
| Imagination Fascination Ltd | Health & social care | 2022 |
| Immaculate Home Improvements Ltd | Construction | 2022 |
| Immortals Draylining Ltd | Construction | 2023 |
| Impact Printing Services Limited | Manufacturing | 2010 |
| Imperial Commercial Services Ltd | Professional & scientific | 2019 |
| Imperial Ventilation Limited | Construction | 2017 |
| Impertitan Ltd | Transport & logistics | 2020 |
| Improve Home Developments Limited | Real estate | 2024 |
| Improve Homes Limited | Construction | 2012 |
| IN Between Time | Arts & recreation | 2009 |
| INA Transport Ltd | Transport & logistics | 2018 |
| Incatext Limited | Manufacturing | 1982 |
| Incommunicado Design Limited | Professional & scientific | 2018 |
| Incrementum Coaching Limited | Professional & scientific | 2017 |
| Independent Living Services (SW) Ltd | Health & social care | 2010 |
| Indigo Childrens Care Homes Ltd | Health & social care | 2020 |
| Infinity Information Technology Limited | Information & communication | 2018 |
| Infinity Maintenance Ltd | Construction | 2023 |
| Infinity Service Ltd | Wholesale & retail | 2014 |
| Infoharbour Ltd | Information & communication | 2025 |
| Ingenium Harwell Property Limited | Real estate | 2024 |
| Ingenium Technical LLP | | 2021 |
| INH Ltd | Real estate | 2021 |
| Inner Sparkle Beauty Ltd | Other services | 2017 |
| Innovative Collaboration Platforms Limited | Professional & scientific | 2025 |
| Innovinity Ltd | Manufacturing | 2020 |
| Innsolutions South West Limited | Wholesale & retail | 2024 |
| Insight Data Limited | Administrative & support | 2006 |
| Inspirational Events and Investments Limited | Hospitality | 2017 |
| Inspire Food Limited | Hospitality | 2019 |
| Inspire Hair Ltd | Other services | 2022 |
| Inspired by Colour Ltd | Other services | 2022 |
| Inspired Design & Build SW Ltd | Construction | 2026 |
| Inspired Management South West Ltd | Professional & scientific | 2018 |
| INSTALLATIONS4U Limited | Construction | 2017 |
| Insulated Conservatory Roofs (South West) Ltd | Construction | 2024 |
| Integra Developments Ltd | Information & communication | 2012 |
| Integrity Virtual Office Planning Limited | Administrative & support | 2012 |
| Integrow Sales Solutions Ltd | Professional & scientific | 2019 |
| Intelligent Wiring Limited | Construction | 2008 |
| Intellisoft Systems Limited | Information & communication | 2014 |
| Interconnect Building Services SW Ltd | Construction | 2025 |
| International Resilience Limited | Professional & scientific | 2017 |
| Intime International Limited | Wholesale & retail | 2024 |
| Inverted Firkin Inns Ltd | Hospitality | 2018 |
| Inwood Nursery Limited | Education | 2011 |
| Ionel Wash Ltd | Administrative & support | 2024 |
| Ionut Constantin Ltd | Transport & logistics | 2025 |
| Iota Garden and Home Limited | Wholesale & retail | 2001 |
| Ipgh Investments | Financial services | 2026 |
| IR Aesthetics Limited | Other services | 2025 |
| Ircom Ltd | Administrative & support | 2024 |
| Irecycle Ireuse Limited | Water & waste | 2022 |
| Isabella &Co. Limited | Professional & scientific | 2015 |
| Isenad Solutions Limited | Information & communication | 2026 |
| ISO Management Systems Limited | Professional & scientific | 2015 |
| Israel Demeter Chemical Group Ltd | Mining & quarrying | 2021 |
| IT ALL Adds UP Ltd | Professional & scientific | 2026 |
| IT8 Recruitment Limited | Administrative & support | 2023 |
| ITS Technical Services Ltd | Professional & scientific | 2018 |
| Ittu Traders Ltd | Wholesale & retail | 2025 |
| Ivory Stage Events Ltd | Hospitality | 2026 |
| J & D Price Limited | Administrative & support | 2015 |
| J & S Building Developments Ltd | Construction | 2023 |
| J a H Consultancy Ltd | Real estate | 2018 |
| J a Integrated Security Systems Ltd | Administrative & support | 2024 |
| J Awang Ltd | Professional & scientific | 2013 |
| J B Pearce Limited | Administrative & support | 2003 |
| J D Turville Ltd | Professional & scientific | 2019 |
| J E & G R Properties Limited | Real estate | 2002 |
| J Gibson Stonemasons Limited | Construction | 2021 |
| J Goddard Services Limited | Professional & scientific | 2024 |
| J H Matthews Security Consultancy Ltd | Administrative & support | 2018 |
| J King Glass & Glazing Limited | Construction | 2011 |
| J M S Transport (SW) Ltd | Transport & logistics | 2025 |
| J Marin GAS Services Ltd | Construction | 2018 |
| J Mckenna Ltd | Health & social care | 2017 |
| J N Baker Limited | Transport & logistics | 1945 |
| J Pickering Consulting Ltd | Administrative & support | 2019 |
| J Rendall Mechanical Services Limited | Construction | 2013 |
| J Richards Property Limited | Real estate | 2021 |
| J S M Developments (SW) Ltd | Construction | 2024 |
| J T Retail Entertainments Limited | Real estate | 2009 |
| J T Retail Properties Limited | Construction | 2014 |
| J W Spary Electrical Limited | Construction | 2014 |
| J Window Cleaning Ltd | Construction | 2019 |
| J&D Hospitality Limited | Hospitality | 2019 |
| J&J Roofing and Building Ltd | Construction | 2025 |
| J&K Express Logistics Ltd | Transport & logistics | 2020 |
| J&P Capital Limited | Professional & scientific | 2018 |
| J. G. Transport (SW) Limited | Transport & logistics | 2014 |
| J.L.Burrow Limited | Financial services | 1962 |
| J.M.S. South West Ltd | Wholesale & retail | 2014 |
| J.R. Shattock Limited | Health & social care | 2019 |
| J.R.Bishop Agri and HGV Services Ltd | Transport & logistics | 2016 |
| J.T MUG Consulting Limited | Health & social care | 2013 |
| J21 Autos Ltd | Wholesale & retail | 2023 |
| J21 Gymnastics Club Ltd | Arts & recreation | 2024 |