| Huppert Engineering (U.K.) Limited | Administrative & support | 1996 |
| Hussar Rail Limited | Professional & scientific | 2024 |
| Hutch Train Limited | Arts & recreation | 2024 |
| Hutton Partners Ltd | Professional & scientific | 2025 |
| HW Capital Group Services Limited | Financial services | 2023 |
| Hybrid Heating and Plumbing Limited | Construction | 2024 |
| Hyde Housing Limited | Health & social care | 2019 |
| Hyperactiv Investments Ltd | Administrative & support | 2025 |
| Hyperwave Technology Ltd | Information & communication | 2020 |
| H`Elite Properties Limited | Construction | 2008 |
| I & a Slater Haulage Ltd | Transport & logistics | 2019 |
| I D Law Limited | Professional & scientific | 2015 |
| I E T Contracts Limited | Administrative & support | 2014 |
| I M & T Associates Limited | Extraterritorial | 1994 |
| I O Fire Solutions Ltd | Construction | 2024 |
| I-Accountancy Limited | Extraterritorial | 2016 |
| I-Flow Technologies Holdings Limited | Financial services | 2026 |
| I-Flow Technologies Ltd | Energy | 2023 |
| I-Fuel Store Ltd | Wholesale & retail | 2022 |
| I-Streetuk Ltd | Wholesale & retail | 2020 |
| I.Billington Surveying Services Ltd | Professional & scientific | 2002 |
| I.F.A Financial Awareness Limited | Financial services | 2002 |
| I3VISION Limited | Extraterritorial | 2014 |
| IAN Hayward Ltd | Administrative & support | 2020 |
| IAN R Cartwright Consulting Limited | Professional & scientific | 2023 |
| IAN Sanderson Cleaning Services Ltd | Administrative & support | 2014 |
| IAN Williams Racing Limited | Administrative & support | 2006 |
| Iar:C Board of Control Ltd | Information & communication | 2026 |
| Ibex Worldwide Limited | Transport & logistics | 2004 |
| Ibfi Limited | Other services | 2024 |
| Ibis Engineering Limited | Professional & scientific | 2026 |
| Icdm Energy Limited | Administrative & support | 2017 |
| Icdm Ltd | Professional & scientific | 2005 |
| Icecap Ltd | Professional & scientific | 2019 |
| Iclad Management Limited | Professional & scientific | 2015 |
| Icloud Development Limited | Wholesale & retail | 2013 |
| Icon Distribution Limited | Wholesale & retail | 2026 |
| Ideal PC Solutions Limited | Other services | 2003 |
| Idevelopfm Limited | Administrative & support | 2021 |
| Idplizz Ltd | Information & communication | 2022 |
| Idriss Cleaning Services Ltd | Administrative & support | 2025 |
| Ignis Group Limited | Construction | 2017 |
| Ignis Investments Ltd | Financial services | 2020 |
| Ignition Components Limited | Manufacturing | 1999 |
| Igpr Technologies Limited | Information & communication | 2017 |
| Iguana Creative Group Ltd | Professional & scientific | 2021 |
| Iguana Exhibitions Limited | Administrative & support | 1993 |
| Ihuoma Properties Limited | Construction | 2017 |
| Iihcs Ltd | Professional & scientific | 2024 |
| IK Building Design Ltd | Construction | 2010 |
| Ikrash Enterprises Ltd | Wholesale & retail | 2025 |
| Iliad Consulting Limited | Information & communication | 2024 |
| Image Holdings Bromsgrove Limited | Real estate | 2010 |
| Image Interiors Limited | Wholesale & retail | 1998 |
| Image Reporting Limited | Health & social care | 2018 |
| Image Technique Limited | Construction | 1997 |
| IMD Transport Solutions Ltd | Transport & logistics | 2026 |
| Imella Design Limited | Professional & scientific | 2019 |
| IMF Electrical Ltd | Construction | 2020 |
| Impression Communications Ltd | Professional & scientific | 2012 |
| Impressive Marketing (UK) Limited | Wholesale & retail | 2014 |
| IN Harmony Music School Limited | Arts & recreation | 2009 |
| IN Mortgages Ltd | Financial services | 2023 |
| In-Lode Ltd | Information & communication | 2012 |
| Inastitch UK Ltd | Other services | 2021 |
| Inception Talent Limited | Administrative & support | 2022 |
| Inclusive Entertainment Group CIC | Professional & scientific | 2026 |
| Independent Claims Recovery UK Limited | Other services | 2001 |
| Independent Fostering Limited | Extraterritorial | 2000 |
| Independent Stairlifts Limited | Wholesale & retail | 2007 |
| Indigo Bonsai | Real estate | 2019 |
| Indigo Bonsai Holdings | Financial services | 2019 |
| Indoors Property Limited | Real estate | 2019 |
| Industrial Ceramic Solutions Limited | Construction | 2017 |
| Industrial Compressors Limited | Other services | 2020 |
| Industrial Contractors Limited | Water & waste | 1982 |
| Industrial Refrigeration Services Group Limited | Financial services | 2022 |
| Industrial Refrigeration Services Limited | Manufacturing | 1992 |
| Industrial Water Jetting Systems Group Limited | Water & waste | 2010 |
| Industrial Water Training Services Limited | Professional & scientific | 2015 |
| Infinity Support Limited | Health & social care | 2023 |
| Infoage IT Solutions Ltd | Information & communication | 2007 |
| ING Consultancy Ltd | Professional & scientific | 2026 |
| Ingram Property Services Ltd | Real estate | 2021 |
| Inside Edge Properties Ltd | Real estate | 2020 |
| Inspect Car Records Ltd | Wholesale & retail | 2025 |
| Inspire Communities (Midlands) Community Interest Company | Health & social care | 2014 |
| Inspired & More Ltd | Administrative & support | 2010 |
| Inspiring Leadership (Events) Ltd | Administrative & support | 2017 |
| Instip Ltd | Manufacturing | 2003 |
| Insys Microelectronics UK Limited | Professional & scientific | 2007 |
| Intake Nutrition Limited | Manufacturing | 2026 |
| Integra Supported Housing Dudley Ltd | Other services | 2017 |
| Integrated Eco Technologies Holdings Limited | Financial services | 2024 |
| Integrated Eco Technologies Limited | Professional & scientific | 2001 |
| Integrated M & C Services Ltd | Professional & scientific | 2009 |
| Integrity Services Limited | Wholesale & retail | 1987 |
| Intelligent Electrical Solutions Ltd | Construction | 2019 |
| Intelligent Mewps Limited | Administrative & support | 2026 |
| Intercept Technology UK Limited | Manufacturing | 2017 |