| Hilton Press Limited | Manufacturing | 1991 |
| Hireable Ltd | Information & communication | 2023 |
| Hitchin Coffee Company Ltd | Hospitality | 2015 |
| Hivetech Ventures Limited | Wholesale & retail | 2017 |
| HK Bookeeping Limited | Professional & scientific | 2025 |
| HL Barn Limited | Hospitality | 2020 |
| HLD Property Developments Limited | Construction | 2020 |
| Hljs Limited | Professional & scientific | 2026 |
| HMC Automotive Limited | Wholesale & retail | 2020 |
| Hncinternational Limited | Professional & scientific | 2023 |
| Hoddesdon (Community) Society of Performing Arts Ltd. | Administrative & support | 2007 |
| Hoddesdon Recovery Ltd | Professional & scientific | 2025 |
| Hodson & Moule Bloodstock Limited | Other services | 2016 |
| Holdsworth & Co Limited | Professional & scientific | 2005 |
| Holes in the Dark Limited | Administrative & support | 1999 |
| Holloway Agency Limited | Administrative & support | 2025 |
| Hollywell Developments Limited | Real estate | 2011 |
| Holman Simmons Construction Ltd | Construction | 2023 |
| Holman Simmons Ltd | Construction | 2016 |
| Home Drawdown Ltd | Extraterritorial | 2018 |
| Home Enhance Ltd | Construction | 2026 |
| Home Farm Barn Court (DBS) Ltd. | Real estate | 2008 |
| Home Oak Developments Ltd | Construction | 2024 |
| Home of Hammam Ltd | Wholesale & retail | 2021 |
| Home Savvy Limited | Professional & scientific | 2024 |
| Honcho Limited | Professional & scientific | 2014 |
| Honest Finance Limited | Financial services | 2016 |
| Honey Lane Management Company Limited | Real estate | 2004 |
| Honeycomb PS Ltd | Professional & scientific | 2018 |
| Hoorain Properties Ltd | Real estate | 2023 |
| Horizon Smart Build Ltd | Construction | 2019 |
| Hornbeck Ltd | Manufacturing | 2011 |
| Hospitality Venues Limited | Administrative & support | 2024 |
| House of Stix Limited | Information & communication | 2017 |
| House of Ukraine Ltd | Wholesale & retail | 2022 |
| HOW APT Limited | Information & communication | 2025 |
| Howard Park Management Co. Limited | Households | 1991 |
| Hrvb Ltd | Professional & scientific | 2021 |
| HS Alpha Limited | Administrative & support | 2003 |
| HTD Installations Ltd | Construction | 2020 |
| Hubertnoble 2 Investments Ltd | Real estate | 2025 |
| Hubertnoble Investments Ltd | Real estate | 2024 |
| Hubertnoble Ltd | Construction | 2020 |
| Huddle Victualling Ltd | Hospitality | 2022 |
| Hughes Construction (London) Ltd. | Construction | 2022 |
| Humbers HOE Management Company Limited | Households | 2014 |
| Hunter and Stone Ltd | Construction | 2014 |
| Hurford Salvi Carr Property Management Limited | Real estate | 1996 |
| Hygamp Limited | Wholesale & retail | 2017 |
| Hyperion Property Development Limited | Real estate | 2004 |
| Hypnobirth Ltd | Education | 2023 |
| I AM & I AM Limited | Professional & scientific | 2012 |
| I Love Hertford Limited | Professional & scientific | 2020 |
| I Security Plus Limited | Administrative & support | 2008 |
| I T Builder Limited | Information & communication | 2001 |
| I W Metals Consulting Limited | Professional & scientific | 2024 |
| I-Hub Limited | Information & communication | 2005 |
| I.M.S. (London) Limited | Financial services | 2001 |
| I.Tech Support Holdings Limited | Financial services | 2014 |
| I.Tech Support Limited | Information & communication | 2004 |
| Iannelli's Coffee Limited | Hospitality | 2026 |
| Iannelli's Gelato Limited | Wholesale & retail | 2021 |
| Iannellis Restaurant Limited | Hospitality | 2023 |
| IBC Show Limited | Administrative & support | 1998 |
| ICN Electrical Ltd | Construction | 2014 |
| Icon Apartments Limited | Households | 2009 |
| Iconiq Group Limited | Other services | 2009 |
| ID Fitness (Waltham Cross) Ltd | Arts & recreation | 2025 |
| IEC Town Planning Consultancy Limited | Administrative & support | 2020 |
| Ignis Protection Limited | Administrative & support | 2021 |
| IJM Building Surveyors Ltd | Financial services | 2020 |
| Ikiel Ltd | Other services | 2023 |
| Ikoniss Ltd | Information & communication | 2011 |
| Ilipa Consulting Ltd | Professional & scientific | 2025 |
| IM2A Investments Ltd | Real estate | 2017 |
| IMH Advisory Group Ltd | Professional & scientific | 2024 |
| IMI Awards Limited | Education | 2007 |
| Immature Garden Ltd | Agriculture & fishing | 2019 |
| Immedica Group Limited | Professional & scientific | 2015 |
| Immedica UK Limited | Wholesale & retail | 2004 |
| Immense Family Investments Limited | Financial services | 2023 |
| Immersion Capital Foundation | Other services | 2014 |
| Immersion Capital LLP | | 2014 |
| Immersion Capital Services (UK) Ltd | Administrative & support | 2014 |
| Impact Property Partners Limited | Real estate | 2021 |
| Imperial Oak Debt Services Ltd | Financial services | 2021 |
| Imperial Place Management Company Limited | Households | 2007 |
| Impex Trading (Global) Ltd | Wholesale & retail | 2005 |
| IMS Brokers Ltd | Financial services | 2019 |
| IN Case Solutions Limited | Manufacturing | 2002 |
| IN for Four Limited | Administrative & support | 2025 |
| Inactive Limited | Households | 2022 |
| Inception Building Contractors Limited | Construction | 2025 |
| Inceptum Limited | Professional & scientific | 2005 |
| Incheq Limited | Administrative & support | 2022 |
| Incisive Marketing Ltd | Professional & scientific | 2021 |
| Independent Network Campaign Ltd | Other services | 2009 |
| Indepth Diving Resorts Limited | Arts & recreation | 2005 |
| Indulgence Professional Beauty Care Ltd | Other services | 2020 |
| Industrial Roofing Specialists Limited | Administrative & support | 2016 |