| HS Real Estates Ltd | Real estate | 2019 |
| HSG Property Services Limited | Households | 2000 |
| HSS Couriers Services Ltd | Transport & logistics | 2025 |
| Htay Consulting Group Ltd | Financial services | 2025 |
| HTM Futures Ltd | Information & communication | 2004 |
| Huda Janjua Ltd | Other services | 2015 |
| Hudson International Limited | Construction | 2017 |
| Hues of Colours Ltd | Wholesale & retail | 2023 |
| Hugh Tuffley Limited | Professional & scientific | 2010 |
| Hugo VO HA Ltd | Real estate | 2024 |
| Hull Sushi Ltd | Hospitality | 2026 |
| Humanidev Tech CIC | Information & communication | 2020 |
| Hummingbird Global Travel Limited | Administrative & support | 2025 |
| Hunchsoft Ltd | Information & communication | 2008 |
| Hunt & Green Limited | Professional & scientific | 2019 |
| Hunters Dog Holidays Limited | Real estate | 2023 |
| Huntingdon Group Limited | Construction | 1958 |
| Hurley Design & Build Limited | Construction | 2002 |
| Hurley Riverside Park Limited | Hospitality | 2001 |
| Hurley Village Shop and Cafe Ltd | Wholesale & retail | 2025 |
| Hurleyford Farm Caravan Park Group Limited | Agriculture & fishing | 2025 |
| Hurleyford Farm Caravan Park Limited | Agriculture & fishing | 2025 |
| Hurleyford Farm Holdings Limited | Agriculture & fishing | 2025 |
| Hurleyford Farm Limited | Agriculture & fishing | 2001 |
| Hurst and Sandler Limited | Professional & scientific | 1935 |
| Hurst Enterprises Ltd | Professional & scientific | 2008 |
| Hussain & Co Tools Ltd | Other services | 2024 |
| Hussain Brothers Store Ltd | Wholesale & retail | 2022 |
| Hussain Investment Holdings Limited | Real estate | 2025 |
| Hutchins Group Ltd | Financial services | 2017 |
| Huxley Asset Management Limited | Financial services | 2025 |
| Huzenix Dynamic Ltd | Construction | 2025 |
| HV Contracts Limited | Professional & scientific | 2013 |
| Hydro Farms Export Limited | Wholesale & retail | 2025 |
| Hydro-Actif@Drummond Ltd | Education | 2020 |
| Hydropower Holdings Limited | Financial services | 2022 |
| Hygge Spaces and Design Ltd | Professional & scientific | 2024 |
| HYL Consulting Services Ltd | Professional & scientific | 2024 |
| Hyland Software Solutions UK Ltd. | Extraterritorial | 1994 |
| Hyland Software UK Ltd | Extraterritorial | 2012 |
| Hyland UK Holdings Limited | Information & communication | 2002 |
| Hyland UK Operations Limited | Information & communication | 2002 |
| Hypescape Ltd | Wholesale & retail | 2021 |
| Hyphen International Limited | Extraterritorial | 2017 |
| I & M Concepts Ltd | Information & communication | 2025 |
| I & M Holdings Limited | Financial services | 2020 |
| I H Investmants Limited | Wholesale & retail | 2017 |
| I-Health Consultancy Limited | Health & social care | 2022 |
| I-Markets International Ltd | Information & communication | 2006 |
| I.P.S. Industrial Power Systems Limited | | 1976 |
| I2E Solutions Ltd | Information & communication | 2015 |
| IA Power Engineering Limited | Professional & scientific | 2018 |
| Iaca Consulting Limited | Professional & scientific | 2016 |
| IAI Consultancy Ltd | Professional & scientific | 2026 |
| Iain LEE Ltd | Information & communication | 2012 |
| Iapex Consultancy Limited | Information & communication | 2017 |
| Ibex Coaching and Training Ltd | Information & communication | 2013 |
| IBL Associates Limited | Professional & scientific | 2000 |
| Icarusclo Ltd | Wholesale & retail | 2022 |
| Ice Mushi Limited | Real estate | 2019 |
| Ice Road Gritters Limited | Administrative & support | 2010 |
| Icknor Associates Limited | Information & communication | 2008 |
| ICO Fire Protection Ltd | Wholesale & retail | 2020 |
| ICO Products Ltd | Wholesale & retail | 2018 |
| Iconflow Markets Limited | Financial services | 2026 |
| Iconiq Interiors and Construction Limited | Construction | 2025 |
| Icrackedit Limited | Information & communication | 2025 |
| ICT Value Limited | Information & communication | 2015 |
| ICU 24-7 Limited | Information & communication | 2008 |
| ICZ Holdings Limited | Financial services | 2024 |
| ICZ Trading Limited | Financial services | 2023 |
| ID Care Services Limited | Health & social care | 2023 |
| IDA Property Limited | Real estate | 2018 |
| Idea Gear International Ltd | Professional & scientific | 2011 |
| Ideal Solutions (South East) Limited | Administrative & support | 2003 |
| Ideomistry Consultancy Ltd | Information & communication | 2015 |
| Idoll UK Ltd | Wholesale & retail | 2015 |
| IDW UK Limited | Administrative & support | 2019 |
| IF Coaching Limited | Education | 2025 |
| IFL Realisations Limited | Administrative & support | 2009 |
| Iflora Limited | Wholesale & retail | 2024 |
| Ifoster Ltd | Health & social care | 2020 |
| IG4 Capital Global Ventures Ltd | Financial services | 2026 |
| Ignite Data Limited | Professional & scientific | 2014 |
| Ignite Dean Limited | Arts & recreation | 2024 |
| Ignite Sports Management Limited | Professional & scientific | 2018 |
| Ijko Catering Services Limited | Hospitality | 2023 |
| Ijko Limited | Professional & scientific | 2023 |
| IJM Engineering Consultants Ltd | Professional & scientific | 2025 |
| IK Property Services Limited | Professional & scientific | 2015 |
| Ikigaiconnect Solutions Limited | Information & communication | 2023 |
| Ikooky Limited | Other services | 2011 |
| Iksansys Limited | Information & communication | 2021 |
| Ilagan Holdings Ltd | Administrative & support | 2025 |
| Ilam Technologies Ltd | Information & communication | 2016 |
| Ilardi Limited | Professional & scientific | 2024 |
| Illapa Cloud Limited | Information & communication | 2017 |
| Illapa Group Limited | Extraterritorial | 2017 |
| Illiria Limited | Professional & scientific | 2011 |
| Illuminate YOU Limited | Professional & scientific | 2016 |