| Home Organisers Limited | Administrative & support | 2015 |
| Home Solutions Roofing Ltd | Construction | 2024 |
| Homefield Surfacing Limited | Construction | 2024 |
| Homeleigh Property Investments Ltd | Real estate | 2022 |
| Homes by Warwick Ltd | Construction | 2005 |
| Homesimple Limited | Administrative & support | 1998 |
| Homsters International Ltd. | Information & communication | 2013 |
| Honey LAB Aesthetics Limited | Other services | 2022 |
| Honiball IT Limited | Information & communication | 2001 |
| Hook Solar Limited | Financial services | 2021 |
| Hope Therapy Limited | Health & social care | 2014 |
| Horiuchi Foundation | Other services | 2011 |
| Horlux Ltd | Wholesale & retail | 2025 |
| Horridge Holding Ltd | Financial services | 2026 |
| Hoss Construction Limited | Construction | 2023 |
| Hot House Franchise Ltd | Professional & scientific | 2024 |
| Hot VOX Limited | Extraterritorial | 2012 |
| House Heating Limited | Construction | 1997 |
| House Heating Solutions Limited | Construction | 2011 |
| House of Developers Ltd | Information & communication | 2025 |
| Howe Property Consultancy Limited | Professional & scientific | 2022 |
| Hoyland IFA | | 1991 |
| Hsquared Property Limited | Construction | 2022 |
| Hubbard Plumbing and Heating Services Limited | Construction | 2010 |
| Hudson & Hill Limited | Professional & scientific | 1922 |
| HUF Haus UK Limited | Construction | 1995 |
| Hugo Management Services Ltd | Professional & scientific | 2015 |
| Hugo Restrepo Limited | Professional & scientific | 2025 |
| Hugo Sound Ltd | Information & communication | 2026 |
| Human & AI Consultancy Ltd | Professional & scientific | 2025 |
| Human Nature by HB Limited | Hospitality | 2017 |
| Human Nature by Heston Blumenthal Limited | Hospitality | 2017 |
| Human Nature by Heston Limited | Hospitality | 2017 |
| Humble Burgers and Shakes Limited | Hospitality | 2021 |
| HUN It’S Personal Ltd | Manufacturing | 2022 |
| Hurcott Limited | Professional & scientific | 2012 |
| Hurst Park Automobiles (W.R.) Limited | Real estate | 1964 |
| Hurst Park Automobiles Limited | Wholesale & retail | 1960 |
| Hutton Homes (Surrey) Limited | Real estate | 2013 |
| Huxter Seven Limited | Professional & scientific | 2014 |
| Hypaiq Limited | Information & communication | 2017 |
| Hyperion Wall Furniture Limited | Manufacturing | 1973 |
| I & a Properties (1999) Limited | Real estate | 2018 |
| I.D. Factory Limited | Professional & scientific | 1999 |
| IAN Southworth Accountancy Services Limited | Professional & scientific | 2005 |
| IAT World Limited | Wholesale & retail | 2026 |
| Ibex Property Group Limited | Construction | 2020 |
| IBI International Limited | Transport & logistics | 1987 |
| IBI International Logistics Limited | Transport & logistics | 1979 |
| IC Real Estate Ltd | Real estate | 2023 |
| Iceland IS Best Limited | Information & communication | 2017 |
| Iconicad Ltd | Administrative & support | 2021 |
| Ics-Digital LLP | | 2009 |
| Idearia Ltd | Administrative & support | 2015 |
| Ifamatch.Com Limited | Administrative & support | 2006 |
| IG Capital Limited | Real estate | 2019 |
| Igcs Limited | Information & communication | 2009 |
| Ignition Commerce Limited | Information & communication | 2025 |
| Igor Sessions Ltd | Professional & scientific | 2022 |
| Iiwii Consultants Ltd | Administrative & support | 2019 |
| Ikag Project Management Consultants Ltd | Construction | 2024 |
| Iknower Limited | Construction | 2018 |
| Illume Electrical Contractors Ltd | Construction | 2019 |
| Illuminous Tree Ltd | Wholesale & retail | 2022 |
| ILR Limited | Information & communication | 2022 |
| Imas Property Ltd | Real estate | 2019 |
| IME Trustees Limited | Extraterritorial | 2002 |
| IMI Consulting Limited | Information & communication | 2008 |
| IMM Projects Limited | Professional & scientific | 2018 |
| Immaculate Conceptions Limited | Professional & scientific | 2013 |
| Immaculate UK Limited | Professional & scientific | 2004 |
| Imperial Caviar Holdings Limited | Financial services | 2025 |
| Imperial Caviar Limited | Wholesale & retail | 2005 |
| Imperium Cyber Consulting Ltd | Administrative & support | 2023 |
| IMR Research and Development PTY Ltd | Information & communication | 2024 |
| Indeco (Property) Limited | Construction | 2012 |
| Independent Content Services Limited | Information & communication | 2002 |
| Indigo Pumpkin Ltd | Mining & quarrying | 2016 |
| Infinite Heating Ltd | Construction | 2023 |
| Infinity Balloons Limited | Other services | 2023 |
| Infinity Heating Services Ltd | Construction | 2021 |
| Influence Limited | Information & communication | 2002 |
| Infotech Trade Services Ltd | Administrative & support | 2013 |
| Inga Ltd | Construction | 2022 |
| Ingenium IT Limited | Information & communication | 2015 |
| Ingham-Lee Enterprises PTY Limited | Education | 2021 |
| Ingraphic Ltd | Other services | 2014 |
| Inicio Bespoke Ltd | Construction | 2019 |
| Inner Radiance Ltd | Health & social care | 2011 |
| Inno Group Holdings Ltd | Financial services | 2024 |
| Inno Partnerships Limited | Professional & scientific | 2019 |
| Inno Prop Ltd | Real estate | 2024 |
| Innops Ltd | Information & communication | 2023 |
| Innova Decor Limited | Wholesale & retail | 2020 |
| Innovation in Business Limited | Other services | 2020 |
| Innovation in Creation Ltd | Professional & scientific | 2018 |
| Innovation in Life Limited | Professional & scientific | 2014 |
| Innovation in Technology Limited | Professional & scientific | 2014 |
| Innovative Accountants (London) Ltd | Professional & scientific | 2020 |
| Innovative Accountants (UK) Limited | Professional & scientific | 2020 |