| Hungry Hub Ltd | Hospitality | 2025 |
| Hunt Arnison Holdings Limited | Professional & scientific | 2022 |
| Hunt Arnison Limited | Financial services | 2014 |
| Hunter's Stores Ltd | Wholesale & retail | 2026 |
| Hunters Court RTM Company Limited | Households | 2010 |
| Huntsman Consultancy Services Limited | Professional & scientific | 2023 |
| Hurley Assets Limited | Wholesale & retail | 2010 |
| Hurley Partners Consultancy Limited | Professional & scientific | 2019 |
| Hurst Drive Management Company Limited | Households | 2013 |
| HW Accountancy Limited | Professional & scientific | 2024 |
| HWK Lighting Limited | Wholesale & retail | 2025 |
| Hybrid Premium Ltd | Professional & scientific | 2014 |
| Hydro Hatch Ltd | Manufacturing | 2026 |
| Hyland Chiropractic Limited | Health & social care | 2002 |
| Hype London Limited | Information & communication | 2010 |
| Hyper Real Productions Ltd | Manufacturing | 2023 |
| Hypernym Ltd | Information & communication | 2023 |
| Hystar Construction Limited | Construction | 1977 |
| Hystar International Limited | Professional & scientific | 1979 |
| I 3 Development Ltd | Professional & scientific | 2003 |
| I AM Helps Ltd | Information & communication | 2020 |
| I&You Limited | Administrative & support | 2015 |
| I'Ve Been Found Ltd | Information & communication | 2014 |
| I-Cap Marine Services Limited | Transport & logistics | 2008 |
| I-Gas Services Ltd | Construction | 2017 |
| I.C.E. Services (UK) Limited | Manufacturing | 2002 |
| I.M.G. Professional Landscaping Ltd | Construction | 2023 |
| Iams Investments Ltd. | Real estate | 2018 |
| IAN Wickens Consulting Limited | Information & communication | 2007 |
| Iawl Limited | Administrative & support | 2012 |
| Icebreaker One Ltd | Information & communication | 2019 |
| ICM Administration Limited | Administrative & support | 2020 |
| ICM Investment Management Limited | Professional & scientific | 2013 |
| ICM Mobility Group Ltd | Financial services | 2020 |
| ICM Reclamation Ltd | Manufacturing | 2023 |
| Icon Kitchens and Bathrooms Ltd | Construction | 2017 |
| Idata Analytics Limited | Information & communication | 2013 |
| IDC Services Limited | Information & communication | 1996 |
| Identicol Ltd | Administrative & support | 2022 |
| Iexpert Limited | Wholesale & retail | 2019 |
| Ifactssa Limited | Administrative & support | 2022 |
| Iffley Court Management Limited | Households | 2007 |
| Igmac Services Limited | Professional & scientific | 2017 |
| Ignite Intelligence Limited | Professional & scientific | 2025 |
| Ignite Talent Global Limited | Administrative & support | 2022 |
| Igor Tattoo Limited | Arts & recreation | 2026 |
| Igreja Crista Manancial DE Aguas Vivas Ltd | Other services | 2024 |
| IHF Group Ltd | Information & communication | 2025 |
| Iiact Ltd | Professional & scientific | 2019 |
| Iile Records Ltd. | Manufacturing | 2016 |
| IJK Regulatory Consulting Ltd | Professional & scientific | 2019 |
| IL Gelatissimo Ltd | Manufacturing | 2023 |
| Ilda Salon Services Ltd | Other services | 2022 |
| Imagine Public Services Ltd | Professional & scientific | 2019 |
| IMIN4U Ltd | Professional & scientific | 2016 |
| Imkt Ltd | Information & communication | 2013 |
| Immediate Construction Consultancy Limited | Administrative & support | 2018 |
| Immer.Film Ltd | Information & communication | 2019 |
| IMP Install Ltd. | Construction | 2014 |
| Impact Nationwide Recruitment Ltd | Administrative & support | 2020 |
| Impact Nationwide Training Ltd | Administrative & support | 2020 |
| Impala GT Ltd | Professional & scientific | 2021 |
| Impel Consultancy Ltd | Health & social care | 2016 |
| Imperial Electrical Services Limited | Administrative & support | 2020 |
| Imperial Health & Wellness Ltd | Health & social care | 2026 |
| Imperial Manor Estate Limited | Real estate | 2026 |
| Imperial Water Services Company Limited | Water & waste | 2004 |
| Impressive Flooring Company Limited | Construction | 2005 |
| Impressive Wedding Ceremonies Limited | Other services | 2017 |
| Imt-Mqa Ltd | Professional & scientific | 2022 |
| Include ME Consulting Ltd | Professional & scientific | 2021 |
| Incomplete Metamorphosis Ltd | Professional & scientific | 2024 |
| Incorporations Squadron Ltd | Construction | 2025 |
| Incremented Limited | Information & communication | 2025 |
| Indaon Consultancy Limited | Information & communication | 2016 |
| Independent Film Studios Ltd | Information & communication | 2021 |
| Independent Surgery Centres Limited | Health & social care | 1994 |
| Independents Bay Limited | Wholesale & retail | 2026 |
| Indigo Nominees Limited | Financial services | 2021 |
| Indigo Property Group Ltd | Real estate | 2026 |
| Indigo Trustees Limited | Administrative & support | 2017 |
| Ineo Advisory Limited | Professional & scientific | 2016 |
| Inex Partners Ltd | Administrative & support | 2024 |
| Infeel (UK) Ltd | Wholesale & retail | 2013 |
| Infinite Leisure Solutions LLP | | 2026 |
| Infinite Roofing Limited | Construction | 2019 |
| Infinitia Limited | Professional & scientific | 2018 |
| Infinity Mechanical Engineering Limited | Construction | 2018 |
| Infinity Reward Consultants Limited | Professional & scientific | 2026 |
| Infinity Technology Services Limited | Information & communication | 2025 |
| Infonair Services Limited | Professional & scientific | 2013 |
| Infor Solutions Limited | Information & communication | 2000 |
| Informed and Connected Limited | Real estate | 2015 |
| Infraboard Limited | Professional & scientific | 2017 |
| Infragistics Emea Limited | Information & communication | 2020 |
| Inframind Solutions Ltd | Professional & scientific | 2025 |
| Inhouse Photography Limited | Professional & scientific | 2016 |
| INK Recruitment Ltd | Administrative & support | 2014 |
| INK Search Limited | Administrative & support | 2017 |
| Inkaid Ltd | Wholesale & retail | 2023 |