| Icon Art LLP | | 2006 |
| Icon Art Ltd | Information & communication | 1987 |
| Icryo Ltd | Wholesale & retail | 2024 |
| ID Plumbing & Heating Limited | Other services | 2017 |
| IDC Business Solutions Ltd | Professional & scientific | 2018 |
| Iddenden Psychological Services Ltd | Health & social care | 2021 |
| Idea Homes Limited | Construction | 2004 |
| Idea KIT Limited | Professional & scientific | 2010 |
| Idezaire Ltd | Information & communication | 2026 |
| IDM Achievers International Campus Limited | Education | 2021 |
| IDM Campus Limited | Education | 2024 |
| Idolast Ltd | Professional & scientific | 2010 |
| Idris Davies Limited | Construction | 1985 |
| Idris Welland Ltd | Real estate | 2026 |
| IDS Transport (UK) Limited | Transport & logistics | 2001 |
| IE Holdco 5 Limited | Financial services | 2022 |
| IEA Environmental Projects Limited | Information & communication | 1987 |
| IEP Technologies Limited | Manufacturing | 2013 |
| Iexcel Healthcare Ltd | Administrative & support | 2024 |
| IF Cleaning Services Limited | Administrative & support | 2025 |
| IFA Compliance Ltd. | Financial services | 2016 |
| IFA Dataflow Limited | Administrative & support | 2003 |
| Ifac Ltd. | Administrative & support | 2005 |
| IFC Certification Limited | Professional & scientific | 2003 |
| IFC Group Limited | Professional & scientific | 2016 |
| IFS Employee Benefits LLP | | 2003 |
| Igloo Estates Limited | Professional & scientific | 2007 |
| Iglu Bars Ltd | Hospitality | 2014 |
| Iglu Bars Technical Services Ltd | Professional & scientific | 2025 |
| Ignatius DUX Ltd | Information & communication | 2018 |
| Igneous Works Ltd. | Construction | 2012 |
| Ignis Interventions Ltd | Extraterritorial | 2024 |
| Ignite Fulfilment Limited | Administrative & support | 2021 |
| Igreja Evangelica Assembleia DE Deus Cheltenham Ltd | Other services | 2017 |
| IHB Market Insight Ltd | Professional & scientific | 2021 |
| IHL Properties Limited | Construction | 2017 |
| Ijlc Solutions Limited | Information & communication | 2011 |
| IJP Construction Services Limited | Professional & scientific | 2013 |
| Ikigai Holistic Management Limited | Health & social care | 2016 |
| Ilco Refrigeration Limited | Other services | 1977 |
| Illman Young Landscape Design Limited | Professional & scientific | 2003 |
| Illuma Care Consultancy Ltd | Health & social care | 2025 |
| Illume Smiles Limited | Health & social care | 2010 |
| Illuxion Ltd | Administrative & support | 2012 |
| Ilogs UK Ltd | Information & communication | 2016 |
| ILP Strategy Ltd | Professional & scientific | 2012 |
| Iltp Limited | Health & social care | 2024 |
| Image Landing Ltd | Manufacturing | 2025 |
| Images Plus Limited | Other services | 2005 |
| Imagination Technology Limited | Information & communication | 2009 |
| Imago BV Ltd | Manufacturing | 2022 |
| IMB Management Limited | Administrative & support | 2016 |
| Imbellis Limited | Wholesale & retail | 2001 |
| Imec Solutions Limited | Construction | 2006 |
| Imix Haulage Limited | Transport & logistics | 2016 |
| Immaculate Cleaning Limited | Administrative & support | 2025 |
| Immaculate Security Professionals Limited | Financial services | 2025 |
| Imono Digital Ltd | Information & communication | 2018 |
| Impala Records Limited | Wholesale & retail | 2026 |
| Impcross Limited | Manufacturing | 1994 |
| Imperador Butcher Limited | Hospitality | 2023 |
| Imperial Apartments Cheltenham (Management) Company Limited | Households | 1996 |
| Imperial Griffin Limited | Real estate | 2025 |
| Imperial Healthcare Services Ltd | Health & social care | 2007 |
| Imperial Hearing Limited | Wholesale & retail | 2006 |
| Imperial House Management (Cheltenham) Limited | Households | 2006 |
| Imperial Paraplanning Ltd | Financial services | 2024 |
| Imperial Property Partners | | 1999 |
| Imperial Square Developments Limited | Construction | 1983 |
| Imperial Square Property Ltd | Real estate | 2022 |
| Imperial Surveyors Ltd | Professional & scientific | 2025 |
| Impi Street Food Ltd | Hospitality | 2025 |
| Improwise Ltd | Professional & scientific | 2010 |
| IMS - Insurance & Mortgage Services Ltd | Financial services | 2002 |
| IMZ Kitchen Limited | Hospitality | 2026 |
| IN & OUT Health Ltd | Hospitality | 2018 |
| IN Document Ltd | Arts & recreation | 2024 |
| IN Retail Ltd | Real estate | 2016 |
| IN Supply Chain Ltd | Professional & scientific | 2023 |
| IN the Drink Golf Ltd | Wholesale & retail | 2022 |
| IN the Frame Catering Limited | Hospitality | 2018 |
| IN the Loop Accounts Ltd | Professional & scientific | 2015 |
| IN the Loop VA Ltd | Professional & scientific | 2020 |
| In-Home Health Group Ltd | Health & social care | 2023 |
| IN2DB Consultants Limited | Information & communication | 2012 |
| IN2PRINT Ltd | Manufacturing | 2022 |
| IN2PRINT Part of Commercial Group Limited | Other services | 2010 |
| Inari Development Limited | Households | 2020 |
| Inca Coaching Limited | Administrative & support | 2021 |
| Inclusion Properties Ltd | Real estate | 2019 |
| Inclusive Leaders Limited | Professional & scientific | 2024 |
| Inclusive Vision Limited | Health & social care | 2017 |
| Incom Gaming Limited | Wholesale & retail | 2015 |
| Incomparable Accessories Sales UK Limited | Wholesale & retail | 2022 |
| Incorporated Guild of Cheltenham Ladies' College | Other services | 1922 |
| Incredible Events Ltd | Arts & recreation | 2006 |
| Incusol Services Limited | Administrative & support | 2014 |
| Incysive Systems Limited | Information & communication | 2011 |
| Indalo Property Management Ltd | Real estate | 2014 |
| Indelible Ventures Limited | Administrative & support | 2023 |