| IG Networks Ltd | Manufacturing | 2013 |
| Ignis Cordis Ltd | Wholesale & retail | 2025 |
| Ignis Engineering Consulting Ltd | Professional & scientific | 2025 |
| IGR Builders Ltd | Construction | 2025 |
| IJS Contracting Ltd | Agriculture & fishing | 2024 |
| IJT Accountancy Ltd | Professional & scientific | 2014 |
| Ikerrin Limited | Hospitality | 2013 |
| Ikigai Collective Ltd | Other services | 2023 |
| Ilex Accountancy Services Limited | Professional & scientific | 2007 |
| Illumify Ltd | Information & communication | 2024 |
| Illuminati Developments Limited | Manufacturing | 2019 |
| IM Medical Limited | Health & social care | 2020 |
| Imagine Mentoring and Support Ltd | Health & social care | 2019 |
| Imaginor Ltd | Information & communication | 2012 |
| Iman Brothers Company Ltd | Real estate | 2025 |
| Imani Empire Limited | Wholesale & retail | 2019 |
| Imec Void Ltd | Extraterritorial | 2017 |
| Imesa Laundry Equipment UK Limited | Wholesale & retail | 2024 |
| Immobillaire Land and Property LLP | | 2015 |
| Impaler T&T Ltd | Transport & logistics | 2022 |
| Impas Solutions Limited | Financial services | 2002 |
| Imperial Corporate Finance Limited | Financial services | 2016 |
| Imperial Dental Group Limited | Health & social care | 2023 |
| Imperial Food & Packaging Limited | Wholesale & retail | 2002 |
| Imperial Global Ltd. | Wholesale & retail | 2015 |
| Imperial Global Property Ltd. | Real estate | 2018 |
| Imperial Herbary Chinese Medicine Centre Ltd | Health & social care | 2001 |
| Imperium Electrical Installations Ltd | Construction | 2019 |
| Impresa Accounting and Finance Limited | Professional & scientific | 2025 |
| Impro Commercial Ltd | Wholesale & retail | 2010 |
| Impulse Purchase Limited | Wholesale & retail | 2009 |
| Imsupporting Limited | Hospitality | 2015 |
| IN & OUT Home & Garden Limited | Construction | 2023 |
| IN & OUT Tech Repairs Ltd | Other services | 2018 |
| IN the Park Catering Limited | Hospitality | 2017 |
| IN the Park Ltd | Hospitality | 2014 |
| IN Town Thai Cuisine Ltd | Hospitality | 2018 |
| Incanet Ltd. | Information & communication | 2000 |
| Incerix Ltd | Hospitality | 2025 |
| Inclusion Gloucestershire | Health & social care | 2016 |
| Inclusiveinsights West Midlands Ltd | Education | 2025 |
| Inclusivise Ltd | Education | 2026 |
| Incontext Consultancy Limited | Administrative & support | 2017 |
| Indectron Ltd | Information & communication | 2008 |
| Indeloy IT Solutions Limited | Wholesale & retail | 2020 |
| Independent Care Solutions (UK) Ltd | Health & social care | 2013 |
| Independent Education Group Limited | Education | 2021 |
| Independent Financial Planning Limited | Financial services | 2002 |
| Independent Psychology Services Ltd | Health & social care | 2013 |
| Independent Roofing Ltd | Construction | 2012 |
| Indergill Ltd | Transport & logistics | 2024 |
| Indian Aroma Limited | Hospitality | 2011 |
| Indian Enroute Ltd | Hospitality | 2020 |
| Indian Memories Ltd | Hospitality | 2014 |
| Indica (2017) Stroud Ltd | Wholesale & retail | 2017 |
| Indigenous Limited | Wholesale & retail | 1999 |
| Indigo House (Cheltenham) Management Limited | Households | 2014 |
| Individualised Care Ltd | Health & social care | 2012 |
| Induction Coil Solutions Limited | Manufacturing | 2015 |
| Indus Mortgages Ltd | Financial services | 2024 |
| Industrial Works Ltd | Construction | 2024 |
| Inex Properties Ltd | Construction | 2023 |
| Infin Homes Ltd | Real estate | 2020 |
| Infinity Driven Limited | Education | 2025 |
| Infinity Mortgage and Protection Services Ltd | Financial services | 2025 |
| Infinity Trillionaire Limited | Professional & scientific | 2017 |
| Info Plumbing Services Limited | Construction | 2001 |
| Infoserv Systems Ltd | Information & communication | 2018 |
| Infowise Services Ltd | Information & communication | 2025 |
| Infrastar Limited | Information & communication | 2017 |
| Infusion GB Holdings Limited | Professional & scientific | 2008 |
| Ingenious Books Ltd | Information & communication | 2022 |
| Ingenuity System Testing Services Limited | Information & communication | 2001 |
| Iniako Solutions Ltd | Administrative & support | 2023 |
| Inkfluence Tattoo Studio Limited | Arts & recreation | 2025 |
| Innerscene Limited | Manufacturing | 2016 |
| INNOCRETE3D Limited | Other services | 2023 |
| Innova Engineering Limited | Manufacturing | 2012 |
| Innovative Financial Software Limited | Information & communication | 1994 |
| Innovatus Consulting Ltd | Information & communication | 2018 |
| Innsworth Express Ltd | Wholesale & retail | 2026 |
| Innsworth Laundry Ltd | Other services | 2022 |
| Innsworth Storage Ltd | Real estate | 2026 |
| Insignia Spirits Limited | Wholesale & retail | 2018 |
| Insisys Ltd | Real estate | 1999 |
| Inspire Plumbing & Heating Services Ltd | Construction | 2022 |
| Inspired Care Services Limited | Administrative & support | 2017 |
| Inspired Heating Solutions Limited | Wholesale & retail | 2003 |
| Inspiring Restaurants Ltd | Hospitality | 2019 |
| Instafood Ltd | Hospitality | 2025 |
| Instant Insight Partners Ltd | Professional & scientific | 2020 |
| Instinctify Limited | Professional & scientific | 2009 |
| Instinctify One Limited | Professional & scientific | 2009 |
| Integrate Sports Ltd | Wholesale & retail | 2021 |
| Integrated Options UK Ltd. | Health & social care | 2019 |
| Integrity Electrical Solutions Ltd | Construction | 2020 |
| Integrity Spheres Consulting (UK) Ltd | Professional & scientific | 2026 |
| Integrum Services Ltd | Professional & scientific | 2017 |
| Intelliplex Multimedia Limited | Information & communication | 1997 |
| Intensive Driving School Ltd | Education | 2018 |