| Inspecteam Hydro Ltd | Professional & scientific | 2012 |
| Inspiration Interiors Limited | Construction | 2020 |
| Inspire FM Ltd | Professional & scientific | 2026 |
| Inspiring Profits Ltd | Professional & scientific | 2026 |
| Insufero Ltd | Wholesale & retail | 2024 |
| Insulate Right Ltd | Construction | 2025 |
| Insurance Factory Limited | Financial services | 1994 |
| Intaa Limited | Financial services | 2017 |
| Integra Property Management Limited | Real estate | 2010 |
| Integral Fire Management Ltd | Public administration | 2023 |
| Integrated Electrical Ltd | Construction | 2020 |
| Integrated Occupational Health Limited | Health & social care | 2017 |
| Integrated Occupational Medicine Limited | Health & social care | 2009 |
| Integrated Resource Solutions Limited | Other services | 2000 |
| Integration Made Simple Ltd | Construction | 2011 |
| Integrity Estate Agents Limited | Real estate | 2023 |
| Intelligent Impacts Limited | Professional & scientific | 2001 |
| Interactive Dreams Limited | Information & communication | 2021 |
| International Consulting Network Ukeig | Professional & scientific | 1996 |
| International Distributors Limited | Professional & scientific | 1998 |
| International Federation for Coaching and Facilitation Ltd | Education | 2022 |
| International House (Paye Group) LLP | | 2022 |
| International Law Limited | Administrative & support | 2015 |
| Interview Playbook Limited | Education | 2025 |
| Investatwo Limited | Administrative & support | 2015 |
| Investor Relations Results Limited | Professional & scientific | 2011 |
| Invicta Architectural Limited | Construction | 2015 |
| Invicta Business Solutions Limited | Information & communication | 2003 |
| Invicta Energy Holdings Limited | Financial services | 2020 |
| Invicta Energy Limited | Professional & scientific | 2002 |
| Invicta Fabrications Ltd | Construction | 2012 |
| Invicta Insurance Services Limited | Financial services | 1987 |
| Invictacut Limited | Construction | 2005 |
| Invoke Distillery Ltd | Manufacturing | 2018 |
| Inyourdiary Limited | Information & communication | 2026 |
| IO Technology Limited | Manufacturing | 1989 |
| Ipsg Limited | Wholesale & retail | 2013 |
| IQ Service and Maintenance Ltd | Construction | 2004 |
| IQ Your Home.Com Limited | Construction | 2002 |
| Iraise Business Services Ltd | Professional & scientific | 2025 |
| Irbaris LLP | | 2009 |
| Irbaris Nominees Limited | Professional & scientific | 2012 |
| Iridium Electrics Ltd | Construction | 2024 |
| Iris 212 Ltd | Real estate | 2016 |
| Ironstone Hospitality Ltd | Hospitality | 2026 |
| Ironthorne Ltd | Administrative & support | 2025 |
| Irvine Partners Limited | Professional & scientific | 2017 |
| Irwell Vehicle Trade Ltd | Administrative & support | 2025 |
| Irwin Consulting Limited | Professional & scientific | 2024 |
| IS Newco 1 Limited | Information & communication | 2016 |
| Isambard Innovation Limited | Professional & scientific | 2019 |
| Iskar Travel Limited | Administrative & support | 2005 |
| Island Harbour Development Ltd | Construction | 2026 |
| Island Harbour Marina (IOW) Limited | Real estate | 2024 |
| Isle of Wight Estates Ltd | Real estate | 2021 |
| ISR Services (UK) Ltd | Professional & scientific | 2006 |
| It's NOT Brain Surgery Ltd | Education | 2026 |
| Itsimple Capital Ltd | Real estate | 2015 |
| IV Four Scents Limited | Wholesale & retail | 2021 |
| Iversen & Associates Limited | Administrative & support | 2009 |
| IVY Hall Diagnostics Ltd | Health & social care | 2012 |
| IVY Land and Planning Ltd | Real estate | 2023 |
| Izletta Catering Solutions Ltd | Hospitality | 2019 |
| J & E Contracting Ltd | Administrative & support | 2022 |
| J & E Property Solutions Ltd | Households | 2023 |
| J & F Accountancy Limited | Professional & scientific | 2013 |
| J & J Driving Services Ltd | Transport & logistics | 2009 |
| J & S TEE (Sales Development) Limited | Wholesale & retail | 1997 |
| J Baker Advisory Ltd | Professional & scientific | 2026 |
| J C Cycles Ltd | Wholesale & retail | 2021 |
| J E Design (Sevenoaks) Limited | Construction | 2018 |
| J J S Parts Limited | Manufacturing | 2011 |
| J K Hugo Limited | Professional & scientific | 2003 |
| J Kemsley LLP | | 2016 |
| J M Services Kent Limited | Other services | 2023 |
| J Mcbride's Contractors Ltd | Manufacturing | 2021 |
| J Murray Limited | Administrative & support | 2019 |
| J N D Smith Associates Limited | Professional & scientific | 2014 |
| J P Phillips Ltd | Manufacturing | 2010 |
| J Pockett and Sons Ltd | Construction | 2019 |
| J Rogers Property and Garden Maintenance Limited | Administrative & support | 2021 |
| J Supply Ltd | Wholesale & retail | 2024 |
| J W R Pearson Limited | Professional & scientific | 2011 |
| J&B Ecom Ltd | Wholesale & retail | 2025 |
| J&B London Limited | Real estate | 2021 |
| J&K Gallery Limited | Wholesale & retail | 2014 |
| J&Mt Ltd | Wholesale & retail | 2024 |
| J&N E-Commerce Ltd | Wholesale & retail | 2025 |
| J. Allen Tiling Limited | Construction | 2025 |
| J. Beckwith Lift Consultancy Limited | Professional & scientific | 2011 |
| J. Blewer & SON Limited | Wholesale & retail | 1978 |
| J.B. Trading Enterprise Limited | Wholesale & retail | 2009 |
| J.Belton Flooring Ltd | Construction | 2024 |
| J.Chaplin & Son(Swanley)Limited | Agriculture & fishing | 1960 |
| J.J. Investments (London) Limited | Real estate | 2017 |
| J.J.Joinery(Uk) Limited | Manufacturing | 2013 |
| J.M.B. Air Conditioning Services Ltd | Construction | 2002 |
| J.Maet&Cie Ltd | Professional & scientific | 2020 |
| J.S. Flooring Limited | | 1987 |
| J.T.Child Studio Limited | Arts & recreation | 2014 |