| Interdive Services Limited | Education | 2016 |
| Interims for Impact Ltd | Professional & scientific | 2025 |
| Interior Needs Limited | Wholesale & retail | 2022 |
| Interiorstyle Ltd | Professional & scientific | 2019 |
| Interioscape Ltd | Construction | 2024 |
| Interjacq Limited | Wholesale & retail | 2022 |
| Intermission Records Ltd | Information & communication | 2009 |
| International Food Systems Ltd | Professional & scientific | 2008 |
| International Radiotherapy Services Ltd | Professional & scientific | 2024 |
| International Sporting Venues Ltd | Arts & recreation | 2020 |
| International Village Education Limited | Education | 2015 |
| Internetpet Limited | Information & communication | 2002 |
| Interwater Ltd | Arts & recreation | 2025 |
| Interwebb Limited | Information & communication | 2024 |
| Inthepress Limited | Information & communication | 2006 |
| Intimacy World Ltd | Wholesale & retail | 2013 |
| Into Play Limited | Health & social care | 2009 |
| Into Property Ltd | Real estate | 2024 |
| Into the Woods Glos Limited | Hospitality | 2016 |
| Intr & Co. Ltd | Administrative & support | 2026 |
| Introsoft Ltd | Information & communication | 2014 |
| Intuos Services Ltd | Transport & logistics | 2021 |
| Intus Electrical Ltd | Construction | 2017 |
| Inva Solutions Limited | Information & communication | 2010 |
| Inversio | Manufacturing | 2025 |
| Inversio 2021 | Manufacturing | 2021 |
| Inveterate Electrical Ltd | Construction | 2026 |
| Invicta Crossfit Glos Limited | Arts & recreation | 2020 |
| Invictus Sports Group Limited | Wholesale & retail | 2026 |
| Ionic Group Ltd | Construction | 2024 |
| Ionos Cloud Holdings Limited | Professional & scientific | 2006 |
| Ionos Cloud Limited | Information & communication | 2000 |
| Ionos Cloud UK Limited | Information & communication | 2026 |
| Ionut Alexandru Sirbu Ltd | Transport & logistics | 2022 |
| Ionworks Ltd. | Information & communication | 2006 |
| IPG Technologies (Whitchurch) Limited | Construction | 2017 |
| Iplus Sales & Marketing Limited | Professional & scientific | 2012 |
| Ipscape Limited | Information & communication | 2005 |
| IQ Haus Ltd | Information & communication | 2025 |
| Iqimma Labs Ltd | Information & communication | 2026 |
| IQM Holdings Limited | Professional & scientific | 2017 |
| IQR Ltd | Administrative & support | 2025 |
| Iram&Sons Limited | Wholesale & retail | 2025 |
| Irenovate Building Solutions Ltd | Construction | 2015 |
| Iris Care Group (England) Limited | Financial services | 2019 |
| Iron Trinity Clothing Ltd | Wholesale & retail | 2025 |
| Ironclad FM Limited | Administrative & support | 2024 |
| Ironclad Oak Limited | Real estate | 2024 |
| IS Spasov Services Ltd | Transport & logistics | 2021 |
| Isabella Violet Limited | Wholesale & retail | 2025 |
| Isalium Ltd | Manufacturing | 2025 |
| Isha Retailers Limited | Wholesale & retail | 2024 |
| Isla Captial Holdings Ltd | Professional & scientific | 2025 |
| Isla Scott Interiors Limited | Wholesale & retail | 2020 |
| Island Bites Kitchen Ltd | Hospitality | 2022 |
| ISM (South West) Limited | Manufacturing | 2011 |
| Ismi Lets Limited | Real estate | 2019 |
| ISO Solutions Limited | Professional & scientific | 2003 |
| Isothermal Ltd | Professional & scientific | 2021 |
| Ispr Trading Ltd | Hospitality | 2025 |
| IST Digital Marketing Ltd | Professional & scientific | 2018 |
| Istanbul Mini Market Gloucester Ltd | Wholesale & retail | 2020 |
| Istela Healthcare Solutions Ltd | Professional & scientific | 2025 |
| IT Integrated Ltd. | Wholesale & retail | 2007 |
| Italian Property Management Ltd. | Households | 2018 |
| ITM Sales (Glos) Ltd | Wholesale & retail | 2025 |
| ITP Developments Limited | Construction | 2002 |
| Itrustlegacy Ltd | Information & communication | 2024 |
| Itsmyhomehistory Limited | Extraterritorial | 2014 |
| Itus Global Holdings Ltd | Administrative & support | 2024 |
| IV Couriers Ltd | Transport & logistics | 2021 |
| Iv&To Group Limited | Wholesale & retail | 2025 |
| Ivor Morris & Sons | | 1982 |
| Ivory & Cotswold Care Group Ltd | Administrative & support | 2026 |
| IVY & Oak Group Ltd | Professional & scientific | 2026 |
| IVY Group Holdings Ltd | Real estate | 2023 |
| IVY Lodge Barns (Birdlip) Limited | Households | 1991 |
| IVY Mews Limited | Professional & scientific | 2013 |
| IVY Resource Group Ltd | Administrative & support | 2016 |
| Izbas 25 Ltd | Wholesale & retail | 2025 |
| IZO Cafecito Limited | Hospitality | 2021 |
| IZO Coffee Limited | Hospitality | 2019 |
| J & C Mills Holdings Ltd | Real estate | 2024 |
| J & G Universal Services Limited | Construction | 2019 |
| J & J Properties Group Ltd | Construction | 2020 |
| J & L Travel and Visa Services Ltd | Administrative & support | 2023 |
| J & M Glous Limited | Hospitality | 2024 |
| J & M Property & Investment Ltd | Construction | 2023 |
| J & Y Glous Limited | Hospitality | 2025 |
| J a Smith Holdings Ltd | Financial services | 2025 |
| J and H Services Ltd | Wholesale & retail | 2020 |
| J and J Brickwork Limited | Construction | 2015 |
| J B Gaynan & SON Limited | Wholesale & retail | 2015 |
| J B Shop PVT Limited | Wholesale & retail | 2024 |
| J Consulting (UK) Limited | Information & communication | 2014 |
| J D Meloscia Carpentry Ltd | Manufacturing | 2024 |
| J D R Karting Limited | Arts & recreation | 1992 |
| J Devine Ltd | Information & communication | 2023 |
| J E C Electrical Ltd | Construction | 2010 |
| J E Clarke Farms Limited | Agriculture & fishing | 2022 |