| Human Results Limited | Professional & scientific | 2003 |
| Hungarian and Szekler National Cultural Group Community Interest Company | Education | 2017 |
| Hunt Investments Ltd | Real estate | 2020 |
| Hunter Stone & Smith Limited | Manufacturing | 2006 |
| Huros Atelier Ltd | Wholesale & retail | 2023 |
| Hurst Bidco Limited | Financial services | 2021 |
| Hurst Holdco Limited | Financial services | 2021 |
| Hurst Midco Limited | Financial services | 2021 |
| Hurst Topco Limited | Financial services | 2021 |
| Hutun Ltd | Other services | 2020 |
| Huzz Limited | Information & communication | 2019 |
| Hydragas and Hydrolastic Service Ltd | Wholesale & retail | 2017 |
| Hydraulic Precision Limited | Manufacturing | 2011 |
| Hydro Earth Ltd | Professional & scientific | 2022 |
| Hydrosure Global Limited | Wholesale & retail | 2013 |
| Hydrosure Holdings Limited | Extraterritorial | 2021 |
| Hynse Ltd | Other services | 2022 |
| Hyper Clean Ltd | Administrative & support | 2026 |
| Hyperion Property Investments Ltd | Real estate | 2021 |
| Hyve'Ed CIC | Energy | 2025 |
| HZ & Bakr Ltd | Wholesale & retail | 2026 |
| I & a Publishing Limited | Information & communication | 2012 |
| I & M Poultry Farm (Midland) Limited | Agriculture & fishing | 2022 |
| I AM Psychic UK Ltd | Arts & recreation | 2024 |
| I DO Catering Limited | Hospitality | 2026 |
| I G Catering Limited | Hospitality | 2018 |
| I Jones Training Ltd | Transport & logistics | 2024 |
| I Jones Transport Services Ltd | Transport & logistics | 2018 |
| I M Property Ltd | Real estate | 2017 |
| I Visualised This Ltd | Information & communication | 2022 |
| I Want Print Ltd | Manufacturing | 2021 |
| I.A.D.M. Holdings Limited | Financial services | 2011 |
| I.P.B Technical Services Ltd | Construction | 2007 |
| I2R Packaging Solutions Limited | Manufacturing | 2006 |
| I54 Property Services Ltd | Households | 2020 |
| Iaimi Limited | Professional & scientific | 2012 |
| IAN Halstead Wills Limited | Professional & scientific | 2015 |
| IAN Richards | Construction | 2004 |
| IAN Turner Limited | Information & communication | 2000 |
| IAR Ltd | Wholesale & retail | 2025 |
| Ibadat Thind Construction Ltd | Construction | 2026 |
| Ibiza Monthly Rentals 25 Ltd | Hospitality | 2024 |
| IBUILD4U Ltd | Construction | 2014 |
| IC Technology UK Limited | Wholesale & retail | 2002 |
| Ice Vapour Limited | Wholesale & retail | 2015 |
| Ichiban Collective Ltd | Financial services | 2026 |
| Iconsys Limited | Manufacturing | 2007 |
| Ideal Access Limited | Manufacturing | 2018 |
| Ideal Home Care Ltd | Health & social care | 2020 |
| Ideal Properties (Shropshire) Limited | Real estate | 2018 |
| Ideal Underfloor Heating Ltd | Wholesale & retail | 2022 |
| IDEAL4CARE Ltd | Administrative & support | 2021 |
| Identalonline Supplies Limited | Wholesale & retail | 2023 |
| Identity Hair & Beauty Salons UK Ltd | Other services | 2024 |
| Idiens Systems Limited | Financial services | 2019 |
| Idjj Properties Limited | Real estate | 2019 |
| Idkn Ltd | Professional & scientific | 2021 |
| Idris Williams Limited | Transport & logistics | 2017 |
| IES Electricians Ltd | Construction | 2016 |
| Ievers Services Ltd | Administrative & support | 2025 |
| IF Solutions Limited | Administrative & support | 2002 |
| Ignite Pathways Ltd. | Health & social care | 2020 |
| IL Consultancy Services Limited | Information & communication | 2023 |
| Ilera Health Ltd | Professional & scientific | 2024 |
| Ileskas Ltd | Other services | 2019 |
| ILH Media Limited | Information & communication | 2021 |
| Illingworth Consulting Ltd | Information & communication | 2019 |
| Illusionservices Ltd | Hospitality | 2024 |
| ILM Junction Ltd | Education | 2022 |
| ILS Reinforced Concrete Ltd | Construction | 2014 |
| IM Property Solution Ltd | Real estate | 2024 |
| Image Flooring Limited | Construction | 2008 |
| Imagiarium Limited | Arts & recreation | 2017 |
| Imagine Training Limited | Information & communication | 2011 |
| Imahdi Ltd | Hospitality | 2021 |
| Imamedic Care Ltd | Health & social care | 2022 |
| Imgn Property Limited | Real estate | 2021 |
| IMH Solutions Limited | Information & communication | 2012 |
| Immersive Transformations Limited | Administrative & support | 2025 |
| Immersiveav Expo Limited | Administrative & support | 2021 |
| Immi's Cakes and Bakes Limited | Wholesale & retail | 2021 |
| Impact Envelopes Mail & Print Limited | Manufacturing | 2017 |
| Impact Mail & Print (UK) Limited | Manufacturing | 2009 |
| Imperial Alarms Limited | | 1986 |
| Imperial Management Services (Shropshire) Limited | Other services | 2009 |
| Impetus Infotech Ltd | Information & communication | 2015 |
| IN Homes Partnership Ltd | Real estate | 2024 |
| IN Property Group Ltd | Real estate | 2023 |
| IN Scope Driver Ltd | Education | 2021 |
| IN the Shed Limited | Professional & scientific | 2011 |
| IN Touch Wellness Ltd | Extraterritorial | 2024 |
| Inatiwe Ltd | Other services | 2019 |
| Include ME TOO (IM2) Limited | Administrative & support | 2009 |
| Inclusive Pratice Partnerships Ltd | Education | 2026 |
| Incoln Ltd | Other services | 2020 |
| Independent Control Systems Limited | Manufacturing | 1987 |
| Independent Events Group Ltd. | Extraterritorial | 2006 |
| Independent Polymer Technology Ltd | Professional & scientific | 2003 |
| Indie Technology Limited | Information & communication | 2025 |
| Indigo Lima Property Ltd | Real estate | 2018 |