| Hythe and Waterside Coaches Limited | Transport & logistics | 1982 |
| Hythe Electrical Services Limited | Construction | 2015 |
| Hythe Garage Services Ltd | Wholesale & retail | 2017 |
| Hythe Hotel Ltd | Hospitality | 2025 |
| Hythe Marina Association (HMA) Limited | Other services | 2007 |
| Hythe Marina Limited | Professional & scientific | 1984 |
| Hythe Marina Village Limited | Real estate | 1981 |
| Hythe Phone Tech Ltd | Wholesale & retail | 2024 |
| Hythe Roofing & Leadwork Specialists Ltd | Construction | 2024 |
| Hyxa Brandify Ltd | Wholesale & retail | 2024 |
| Hyxa Connect Ltd | Wholesale & retail | 2013 |
| HYZ Containers Limited | Transport & logistics | 2025 |
| I & D Developments Limited | Construction | 2018 |
| I & H Sumra Ltd | Hospitality | 2019 |
| I & J Flooring Limited | Construction | 2010 |
| I a N (Electrical) Limited | Construction | 2014 |
| I AM BB Ltd | Wholesale & retail | 2012 |
| I AM in Print Ltd | Information & communication | 2021 |
| I CAN FIX Your Car Ltd | Wholesale & retail | 2023 |
| I F C Welding Ltd | Construction | 2023 |
| I in the Sky Ltd | Manufacturing | 2018 |
| I Love Life Therapies Limited | Health & social care | 2023 |
| I Love Vapes Worthing Ltd | Wholesale & retail | 2025 |
| I M I Properties Ltd | Real estate | 2024 |
| I Move Courier Ltd | Transport & logistics | 2023 |
| I P Business Services Limited | Professional & scientific | 2021 |
| I Roberts Property Ltd | Real estate | 2024 |
| I SAW U First Limited | Health & social care | 2026 |
| I Speak Yoruba TOO Ltd | Education | 2022 |
| I T Flooring (Southern) Limited | Construction | 2017 |
| I&L Stores Ltd | Wholesale & retail | 2025 |
| I&P Construction Ltd | Construction | 2025 |
| I'M CRE8TIVE Design Ltd | Professional & scientific | 2014 |
| I'M Here Champions Network Ltd | Education | 2024 |
| I-Educate YOU Limited | Real estate | 2009 |
| I. a & Sons Property Management Limited | Real estate | 2023 |
| I. Atkins Limited | Construction | 1996 |
| I.A.C. Healthcare Limited | Health & social care | 2014 |
| I.A.T.A.Spray Ltd | Wholesale & retail | 2017 |
| I.D.M Building Limited | Construction | 2017 |
| I.J.B Plumbing & Heating Ltd | Construction | 2003 |
| I.L. Tooling Limited | Manufacturing | 1999 |
| I.M.Currie Formwork Ltd | Construction | 2015 |
| I.P. Systems Limited | Professional & scientific | 2009 |
| I.Sharp Cycles Ltd | Arts & recreation | 2023 |
| I.T. DEV Limited | Information & communication | 2003 |
| I.T. Explained Ltd | Information & communication | 1999 |
| I.T. Works for Business Limited | Information & communication | 1998 |
| I.V. Investments Limited | Real estate | 1991 |
| I2MOTIVATE Limited | Professional & scientific | 2011 |
| I2O Water International Holdings Limited | Financial services | 2012 |
| I2O Water Ltd | Professional & scientific | 2005 |
| IAN Fielder Ltd | Health & social care | 2013 |
| IAN Golds Tackle Developments Ltd | Manufacturing | 1996 |
| IAN Gray Properties Ltd | Real estate | 2016 |
| IAN Hunter Driver Hire Limited | Transport & logistics | 2010 |
| IAN JON Oliver Ltd | Extraterritorial | 2024 |
| IAN Judd & Partners LLP | | 2007 |
| IAN Knight Consulting Ltd | Professional & scientific | 2016 |
| IAN Walker Sailing Ltd | Arts & recreation | 2023 |
| Ianis Trans Ltd | Transport & logistics | 2016 |
| Iasonia Ltd | Professional & scientific | 2023 |
| Iast Rental and Retail Limited | Wholesale & retail | 2017 |
| Ibcon Construction Limited | Construction | 1983 |
| Ibcon Property Investments Limited | Real estate | 2025 |
| Ibex Homes Limited | Construction | 2007 |
| Ibex Land and Property Limited | Extraterritorial | 2014 |
| IBF Contractors Limited | Construction | 2010 |
| IBG Global Limited | Extraterritorial | 2015 |
| Ibounce Ltd | Hospitality | 2026 |
| Ibrar Ltd | Construction | 2025 |
| Ibsautomotors Ltd | Wholesale & retail | 2025 |
| Iburnham Ltd | Hospitality | 2013 |
| IC Development and Consulting Limited | Construction | 2026 |
| IC MAX Group Holdings (UK) Ltd | Extraterritorial | 2006 |
| ICC Property Ltd | Administrative & support | 2006 |
| Ice Cool Servicing Ltd | Professional & scientific | 2021 |
| Icebell Limited | Extraterritorial | 2017 |
| Iceberg Studios UK Ltd | Information & communication | 2022 |
| Iceir Medical Limited | Professional & scientific | 2024 |
| Icenium Ltd | Information & communication | 2014 |
| Ichiwas Limited | Health & social care | 2012 |
| ICN Medical Ltd | Health & social care | 2022 |
| Icon Autos Ltd | Wholesale & retail | 2016 |
| Iconic Ideas Ltd | Professional & scientific | 2018 |
| Iconic Impact Group Limited | Professional & scientific | 2018 |
| Iconic Private Limited | Wholesale & retail | 2025 |
| Icpd Properties Limited | Real estate | 2022 |
| ID Craft Ltd | Manufacturing | 2025 |
| ID Electrical and Mechanical Ltd | Professional & scientific | 2016 |
| Idacab Ltd | Transport & logistics | 2022 |
| Idad Holdings Ltd | Professional & scientific | 2014 |
| Idad Limited | Financial services | 2002 |
| Idas Limited | Information & communication | 1993 |
| IDC Electrical (Southern) Limited | Construction | 2002 |
| Idea Professional Ltd | Professional & scientific | 2020 |
| Ideal Leisure Limited | Hospitality | 2005 |
| Ideal Modules Limited | Manufacturing | 2017 |
| Ideal Shutters Ltd | Construction | 2020 |
| Ideas Alchemy Consulting Limited | Professional & scientific | 2018 |