| Holidriver Limited | Transport & logistics | 2019 |
| Holjen Limited | Professional & scientific | 2002 |
| Hollie Homes Limited | Real estate | 2019 |
| Home County Public Houses and Hotel Rooms Ltd | Hospitality | 2025 |
| Home County Public Houses Ware Limited | Hospitality | 2015 |
| Home ED Kids C.I.C. | Administrative & support | 2025 |
| Homes & Harmony Ltd | Real estate | 2025 |
| Homesteads Limited | Real estate | 1963 |
| Homewise Colchester Ltd | Construction | 2022 |
| Honeybear House Day Nursery Limited | Education | 2015 |
| Honeybear House Limited | Education | 2000 |
| Honeywood Enterprises Limited | Real estate | 1989 |
| Hope Springs Health Group Ltd | Public administration | 2025 |
| Hopeful Holdco Limited | Financial services | 2021 |
| Horsecroft 2019 Limited | Hospitality | 2019 |
| Hotel Lock & Safe Ltd | Manufacturing | 2020 |
| HPI Europe Limited | Construction | 2013 |
| HPP Capital Limited | Real estate | 2019 |
| HR Landscaping and Tree Care Ltd | Administrative & support | 2022 |
| Huggycare Limited | Health & social care | 2024 |
| Humberside Internet Services Limited | Professional & scientific | 1995 |
| Humberstone Chemicals Ltd | Wholesale & retail | 2019 |
| Huntlea Holdings Limited | Real estate | 2023 |
| HUS Investments Limited | Real estate | 2021 |
| Hylton Capital Limited | Real estate | 2018 |
| I AM Emily Marketing Ltd | Information & communication | 2025 |
| I M a Design Limited | Professional & scientific | 2011 |
| I Y S Control Systems Limited | Manufacturing | 2001 |
| I-Fix Electrical & Mechanical Services Ltd | Manufacturing | 2015 |
| I-Fix Industrial Doors Limited | Administrative & support | 2016 |
| I.M.M.I Investment Limited | Real estate | 2013 |
| IAA Capital Ltd | Real estate | 2026 |
| Ibneiah Consultancy Ltd. | Professional & scientific | 2024 |
| Icare Phone Repairs UK Ltd | Wholesale & retail | 2026 |
| Iceni Consulting Limited | Professional & scientific | 2023 |
| Iceni Windows Limited | Manufacturing | 2003 |
| ID Outdoor Advertising Ltd | Professional & scientific | 2018 |
| ID Signworks Ltd | Professional & scientific | 2021 |
| Iddigi Limited | Information & communication | 2015 |
| Ideal Cars Essex Limited | Wholesale & retail | 2023 |
| Ideal Climate Limited | Construction | 2019 |
| IES Works Ltd | Manufacturing | 2020 |
| IFB Limited | Transport & logistics | 2010 |
| Ignovae Ltd | Information & communication | 2025 |
| Ilford High Road Limited | Real estate | 2016 |
| Immaculate Window Cleaning Services Ltd | Administrative & support | 2025 |
| Immersasim Ltd | Information & communication | 2023 |
| Immobiliare Cardi Marmi Limited | Real estate | 2016 |
| Immy 216 Ltd | Financial services | 2024 |
| Imperial Property Management Services Limited | Administrative & support | 2015 |
| In-Press Photography Limited | Professional & scientific | 1998 |
| Inarco Investments Limited | Real estate | 2013 |
| Inca Futures | | 1998 |
| Indifit Limited | Administrative & support | 2003 |
| Industrial & Media Services Ltd | Information & communication | 2016 |
| Industrial Cladding and Roofing Specialists Limited | Construction | 2010 |
| Industrial Composition Flooring Limited | Construction | 2008 |
| Infatech Ltd | Information & communication | 2017 |
| Infinity Marine Services Ltd | Mining & quarrying | 2020 |
| Information Technology Matters Limited | Information & communication | 1985 |
| Infrastructure Asset Management Ltd | Professional & scientific | 2024 |
| Innco Trading Limited | Professional & scientific | 2009 |
| Innovate Dance and Entertainment Ltd | Arts & recreation | 2026 |
| Innovational Planning Consultancy Services Ltd | Professional & scientific | 2019 |
| Innovitmedic Ltd | Health & social care | 2025 |
| Inoheat Limited | Construction | 2017 |
| Inspire Quality Limited | Transport & logistics | 2020 |
| Inspires MAT | Education | 2013 |
| Integrate Wellbeing Ltd | Transport & logistics | 2026 |
| Integrity Education Ltd | Education | 2022 |
| Interestnet Limited | Professional & scientific | 1999 |
| International Federation of Adjusting Associations | Other services | 2006 |
| Inverness Internet Services Limited | Professional & scientific | 1995 |
| Investate Limited | Professional & scientific | 2018 |
| IOA Limited | Other services | 1999 |
| Iresolve International Ltd | Extraterritorial | 2020 |
| Iron MAT & NIC Investment Limited | Real estate | 2022 |
| Iron MAT & NIC Limited | Real estate | 2019 |
| IS What IT IS Studios Ltd | Administrative & support | 2021 |
| Island Stories Ltd. | Hospitality | 2016 |
| Isle of Wight Internet Services Limited | Professional & scientific | 1995 |
| Isohh Ltd | Education | 2022 |
| IT Connected Ltd | Information & communication | 2016 |
| IT Positive Limited | Information & communication | 2013 |
| ITS Lifting Ltd | Professional & scientific | 2023 |
| ITS Wonkey Limited | Other services | 2007 |
| J & G Freight Services Ltd | Transport & logistics | 2025 |
| J & M Rice Bodyworks Limited | Wholesale & retail | 2014 |
| J C Leisure Solutions (UK) Limited | Manufacturing | 2014 |
| J R Mason Ltd | Construction | 2019 |
| J Smart Roofing Ltd | Construction | 2021 |
| J&Cf Group Ltd | Professional & scientific | 2022 |
| J&J Scott Properties Limited | Real estate | 2025 |
| J&R Service and Repair Ltd | Wholesale & retail | 2025 |
| J-Benn Finance Ltd | Professional & scientific | 2017 |
| J. Allen Installations Limited | Construction | 2002 |
| J. Freeman Builds Limited | Construction | 2017 |
| J.D Timberframing Ltd | Construction | 2017 |
| J.E. Putney and Sons (Plasterers) Ltd. | Administrative & support | 1996 |
| Jaca Welling Limited | Administrative & support | 2018 |