| Identity Global Shared Services Limited | Extraterritorial | 2025 |
| Identity Global Travel Limited | Extraterritorial | 2025 |
| Identity Shared Services Limited | Professional & scientific | 2022 |
| Identity Technical and Scenic Limited | Extraterritorial | 2025 |
| Identity Travel Limited | Administrative & support | 2024 |
| IJS Engineering Limited | Administrative & support | 2011 |
| Illuminate Fitness & Wellbeing Limited | Health & social care | 2024 |
| Image 1ST Limited | Manufacturing | 2004 |
| Image Contract Flooring Limited | Construction | 1992 |
| Imedia Communications Limited | Professional & scientific | 2003 |
| Imex Ceramics UK Ltd | Wholesale & retail | 2010 |
| Impact Civils Group Limited | Financial services | 2024 |
| Impact Formwork & Civils Limited | Construction | 2018 |
| Impact Formwork Limited | Extraterritorial | 2020 |
| Imperial Construction Corporation Limited | Construction | 2024 |
| Imperial Construction Properties Limited | Construction | 2025 |
| Import Engine Works Ltd | Wholesale & retail | 2025 |
| Inde EV Limited | Manufacturing | 2021 |
| Independent Heating and Cooling Ltd | Professional & scientific | 2004 |
| Independent Holdings Limited | Professional & scientific | 2003 |
| Indigo Building Services Limited | Construction | 2015 |
| Indigo Catering Equipment Limited | Wholesale & retail | 2013 |
| Indigo Family Law Ltd | Professional & scientific | 2019 |
| Indigo Services Holding Limited | Financial services | 2020 |
| Infinitas R & D Limited | Professional & scientific | 2013 |
| Ingham House Limited | Health & social care | 2003 |
| Inglis Hall and Co Limited | Construction | 2013 |
| Inkqbator Ltd | Manufacturing | 2021 |
| Installed Security Limited | Construction | 2015 |
| Instep Professional Footcare Limited | Health & social care | 2011 |
| Integrated Electrical Services (UK) Limited | Construction | 2007 |
| Interfirm Limited | Professional & scientific | 2002 |
| International Freightguard Ltd | Administrative & support | 2018 |
| Iona Close (Residents Association) Limited | Other services | 2000 |
| IOW Eco Reserve Limited | Professional & scientific | 2010 |
| Ircj Limited | Health & social care | 2024 |
| ISL Anaesthesia and Medical Services Ltd | Health & social care | 2025 |
| IVF Couriers LLP | | 2015 |
| IVY Recrods Limited | Information & communication | 2022 |
| Iwave Systems Ltd | Information & communication | 2021 |
| J & E Grant Properties Limited | Real estate | 2021 |
| J & L Properties South East LLP | | 2023 |
| J & S Cabinets Limited | Manufacturing | 2014 |
| J ASH Brickwork & Building Services Ltd | Construction | 2024 |
| J Collins Ltd | Construction | 2017 |
| J F Construction & SON Limited | Construction | 2003 |
| J F H Farming Limited | Agriculture & fishing | 2017 |
| J F Stoneworks Limited | Manufacturing | 2011 |
| J G Communications 1066 Limited | Other services | 2002 |
| J Heynes Holdings Limited | Financial services | 2024 |
| J Kemp Consultancy Ltd | Professional & scientific | 2020 |
| J M Cole Consultancy Ltd | Professional & scientific | 2012 |
| J M Legal Limited | Administrative & support | 1990 |
| J Redman Medical Services Limited | Health & social care | 2018 |
| J S Gedge Limited | Wholesale & retail | 2002 |
| J Septimus Limited | Health & social care | 2021 |
| J Smith (Electrical Services) Ltd | Construction | 2022 |
| J Young Plastering Limited | Construction | 2018 |
| J&D Smith Properties Limited | Real estate | 2019 |
| J. Hooper Building Services Ltd | Construction | 2003 |
| J. Martin Preservations Ltd | Construction | 2014 |
| J. Roberts Electrical Services Ltd | Construction | 2008 |
| J.E.D Plumbing & Heating Ltd | Construction | 2017 |
| J.G Build & Break Limited | Construction | 2011 |
| J.H. Payne & Sons Limited | Construction | 1985 |
| J.S. Refrigeration Services Ltd | Manufacturing | 2005 |
| J.S.D. Rail Holdings Limited | Administrative & support | 2023 |
| J.S.D. Rail Limited | Extraterritorial | 2019 |
| Jack of Spades Limited | Administrative & support | 2019 |
| Jack Rowe Physiotherapy Ltd | Other services | 2026 |
| Jack Waghorn Limited | Extraterritorial | 2004 |
| Jacks Franchising Limited | Other services | 2025 |
| Jacques PT Property Ltd | Real estate | 2024 |
| JAH Medical Services Limited | Health & social care | 2022 |
| Jamak Limited | Construction | 2025 |
| James Boardman Limited | Health & social care | 2018 |
| James Builders Ltd | Construction | 2013 |
| James Knock Anaesthetics Limited | Health & social care | 2022 |
| James Pollard Investments Limited | Financial services | 2021 |
| James Walkington Limited | Health & social care | 2022 |
| James Wright Medical Ltd | Health & social care | 2024 |
| Jamica Holdings Limited | Construction | 2025 |
| Jamla Commercial Ltd | Real estate | 2025 |
| Jamla Ltd | Real estate | 2023 |
| Janeway Contracts Limited | Extraterritorial | 2016 |
| Jarvis & Tattam Limited | Extraterritorial | 2019 |
| Jaww Ltd | Health & social care | 2016 |
| Jayton Brown Limited | Real estate | 2017 |
| Jayton Trading Company Ltd | Administrative & support | 2005 |
| JB Coffee Solutions Limited | Other services | 2024 |
| JB Landscaping Ltd | Administrative & support | 2015 |
| JC Asset Investment Limited | Real estate | 2022 |
| JC Painting and Decorating Limited | Construction | 2010 |
| JDC Electrical Services Ltd | Construction | 2022 |
| Jdrf Holdings Limited | Professional & scientific | 2002 |
| JDS Plumbing & Heating Services Ltd | Construction | 2023 |
| Jeary Developments Limited | Construction | 1999 |
| Jellyfish Design Ltd | Professional & scientific | 2009 |
| Jeremyco Limited | Households | 2013 |
| Jersey Chocolate Limited | Professional & scientific | 2012 |