| Inasec Limited | Administrative & support | 2004 |
| Incorporated System Solutions Limited | Administrative & support | 2005 |
| Incro Limited | Manufacturing | 1993 |
| Indev Gauging Systems Limited | Administrative & support | 2004 |
| Industrial Brushware Limited | Manufacturing | 1945 |
| Industrial Installation Services Limited | Administrative & support | 2003 |
| Industrial Investments (Midlands) Limited | Construction | 2000 |
| Industrial Resource Management Limited | Arts & recreation | 2001 |
| Industrial Roofing & Maintenance Limited | Construction | 2004 |
| Industrial Washing Machines Limited | Manufacturing | 2003 |
| Infinity Edge Solutions Ltd | Administrative & support | 2016 |
| Infolink Trading Limited | Information & communication | 2006 |
| Ingisystems Limited | Administrative & support | 2004 |
| Initial Management Limited | Real estate | 1999 |
| INK Point Education and Training Limited | Wholesale & retail | 2023 |
| Inlander LOW Voltage Limited | Other services | 2007 |
| Inos Materials Co., Ltd | Extraterritorial | 2023 |
| Installation & Fabrication Services Limited | Construction | 2006 |
| Instructor Standard Authority Ltd | Education | 2015 |
| Int-Elect (Birmingham) Limited | Construction | 2007 |
| Inteblu Ltd | Wholesale & retail | 2022 |
| Integula Consulting Limited | Professional & scientific | 2007 |
| Intel Security Limited | Administrative & support | 2010 |
| Intelligent Media Group Limited | Households | 2003 |
| Intercity Networks Limited | Information & communication | 1987 |
| Intercity Technology Limited | Information & communication | 1985 |
| Interclass Surfacing Limited | Construction | 1992 |
| Intercoat Industrial Lacquers Limited | Manufacturing | 1983 |
| Intercoat Industrial Paints Limited | Manufacturing | 1975 |
| Interfax Acuflow Limited | Manufacturing | 1974 |
| Intergrid Limited | Administrative & support | 2005 |
| Interior Expressions Limited | Wholesale & retail | 2000 |
| Interior Service Limited | Construction | 2003 |
| Interlink Design & Display Limited | Manufacturing | 1987 |
| Interlink Electrical Limited | Construction | 1996 |
| Introrange Limited | | 1984 |
| Ionida Limited | Information & communication | 2002 |
| IP Developments Limited | Construction | 2004 |
| IP Property Rentals Limited | Real estate | 2007 |
| IR Security and Safety Thomson Group Limited | Professional & scientific | 1969 |
| IS Verwaltung Limited | Administrative & support | 2004 |
| Isaac H. Grainger & SON Limited | Manufacturing | 1956 |
| Isaac.Uk.Com. Limited | Arts & recreation | 2002 |
| Isha Planning Limited | Other services | 2019 |
| Islamic Holidays Limited | Professional & scientific | 2006 |
| Islamic Relief (UK) | Health & social care | 2005 |
| Island Manor Limited | Real estate | 2003 |
| Isonax | Financial services | 2021 |
| ISP Auto Trading Company Limited | Wholesale & retail | 2024 |
| Israel Gidro Chemical Group Co., Ltd | Mining & quarrying | 2023 |
| Israel Haifa Agricultural Science and Technology Co., Ltd | Mining & quarrying | 2023 |
| Israel Harvest Biotechnology Co., Ltd. | Extraterritorial | 2020 |
| IT Again Limited | Other services | 2008 |
| IT Electrical (Coventry) Limited | Construction | 2004 |
| IT in Sutton Limited | Information & communication | 2001 |
| J & B (Midlands) Limited | Health & social care | 2003 |
| J & J Coil Slitting Limited | Manufacturing | 2001 |
| J & T Mccafferty Limited | Construction | 2005 |
| J D Scaffolding and Supplies Ltd | Construction | 2024 |
| J K Cleaning Supplies Limited | Wholesale & retail | 2004 |
| J L C Enterprises Ltd | Real estate | 2007 |
| J Lynex Property Maintenance Services Limited | Construction | 2002 |
| J P Fire Stoppers Ltd | Construction | 2025 |
| J S D Donsons Limited | Professional & scientific | 2007 |
| J S D Trimat Limited | Professional & scientific | 2007 |
| J S Tool & Gauge Company Limited | Manufacturing | 1996 |
| J&A Associates (UK) Co Ltd | Real estate | 2003 |
| J. C. (Holdings) Limited | Construction | 1973 |
| J. Filby Limited | Manufacturing | 1957 |
| J.E. Bowen Transport Limited | Transport & logistics | 2000 |
| J.M.S. Management Services Limited | Professional & scientific | 1995 |
| J.M.Whitty Limited | Wholesale & retail | 2007 |
| J.P.M. Press Brake Sections Limited | Manufacturing | 1980 |
| J.S.E.T. Limited | Construction | 2007 |
| J.T.Egginton,Limited | Wholesale & retail | 1948 |
| Jade WOK Restaurants Limited | Hospitality | 2007 |
| Jaika Group Limited | Financial services | 2020 |
| Jaika Healthcare Limited | Public administration | 2020 |
| Jajo Groundworks Ltd | Construction | 2002 |
| James Janitorial Ltd | Professional & scientific | 2007 |
| James W. Shenton Limited | Manufacturing | 1975 |
| Jamie Hughes D&W Ltd | Extraterritorial | 2007 |
| Jamya Limited | Wholesale & retail | 2021 |
| Jangchub Ling Buddhist Centre | Other services | 2004 |
| Jannah Casa Ltd | Real estate | 2024 |
| Jarvis Enterprises Limited | Professional & scientific | 2009 |
| Jawel Paints (West Midlands) Limited | Wholesale & retail | 1983 |
| Jaxcom Limited | Information & communication | 2000 |
| Jayess Training Limited | Professional & scientific | 2003 |
| Jayridge Limited | Information & communication | 1992 |
| JCM Civil Engineering Limited | Construction | 2001 |
| JD & SB Property Limited | Real estate | 2025 |
| JDA Utilities Limited | Construction | 2003 |
| JDS Design Consultants UK Limited | Administrative & support | 1996 |
| Jedgoco Ltd | Health & social care | 2015 |
| Jem's Beauty Haus Ltd | Other services | 2023 |
| Jfdip Consulting Limited | Professional & scientific | 2006 |
| JFR Design Limited | Information & communication | 2001 |
| JH Performance Racing Limited | Arts & recreation | 2004 |
| JHA Properties Ltd. | Real estate | 2007 |