| Herts and Essex Canine Fertility Clinic Ltd | Other services | 2020 |
| Herts Transport Limited | Transport & logistics | 2024 |
| Hertstone Ltd | Manufacturing | 2025 |
| Hertswood Window and Door Restorations Ltd | Construction | 2019 |
| Hertz and London Tutoring Ltd | Education | 2023 |
| Heston Residential Ltd | Real estate | 2026 |
| Heyalki Ltd | Professional & scientific | 2025 |
| Heycutie Ltd | Wholesale & retail | 2025 |
| HGF Nexus Limited | Information & communication | 2026 |
| HH Food Consultancy Limited | Hospitality | 2022 |
| Hi-Line Event Services Ltd | Arts & recreation | 2018 |
| Hidari Holdings Ltd | Financial services | 2026 |
| Higgs & Mitchell Ltd | Administrative & support | 2022 |
| High Cross Estates Limited | Real estate | 1929 |
| Highbury Broadway Developments Limited | Construction | 2016 |
| Highend Limited | Real estate | 2011 |
| Highgrove International Limited | Other services | 2018 |
| Highsky Development Limited | Construction | 2021 |
| Highview Farm Management Company Limited | Households | 2021 |
| Hilaire Interiors Ltd | Construction | 2019 |
| Hill Court Management Services Limited | Real estate | 1998 |
| Hillson Commercial Services Ltd | Wholesale & retail | 2011 |
| Hinchley Wood Orthodontics Ltd | Health & social care | 2018 |
| Hksc Investments Ltd | Real estate | 2016 |
| HM Consultancy London Limited | Administrative & support | 2021 |
| HM Electrical Contractors Limited | Construction | 2017 |
| HN3I Ltd | Administrative & support | 2013 |
| Hoad Ltd | Construction | 2017 |
| Hobdays Estates Limited | Real estate | 2001 |
| Holding Heart of Joy Limited | Financial services | 2025 |
| Holiday Direct North London Ltd | Hospitality | 2009 |
| Holistic Healthcare North Hertfordshire Ltd | Health & social care | 2023 |
| Holyhead Investments Ltd | Real estate | 2018 |
| Holyland Investing and Acquisitions Limited | Financial services | 2008 |
| Home Counties Archaeology Ltd | Professional & scientific | 2026 |
| Home Fortress Locksmiths Ltd | Administrative & support | 2022 |
| Home Hygiene (London) Limited | Administrative & support | 2007 |
| Home on Wheels Ltd | Manufacturing | 2023 |
| Homechoice Properties Limited | Real estate | 1997 |
| Homes by Heath Limited | Real estate | 2026 |
| Homes Property Management Limited | Real estate | 2008 |
| Homestead Plumbing Limited | Construction | 2017 |
| Hometown Property Limited | Real estate | 2018 |
| Hometz Limited | Professional & scientific | 2015 |
| Homewares (Walsall) Limited | Construction | 1971 |
| Honey Bear Products Ltd | Wholesale & retail | 2025 |
| Hons Foyzul Islam Limited | Administrative & support | 2012 |
| Hope Street Concierge Limited | Administrative & support | 2024 |
| Hopwoods Holdings Limited | Financial services | 2023 |
| Hordle Cliff House Limited | Administrative & support | 1986 |
| Hornbeams Limited | Households | 1988 |
| Hot Plates PR Limited | Professional & scientific | 2026 |
| Hotel on Time Ltd | Administrative & support | 2015 |
| Housemate Space Limited | Real estate | 2023 |
| Houseproud Estates Limited | Real estate | 2006 |
| Housing Accommodation Limited | Households | 2024 |
| Houstanding Builders Ltd | Construction | 2018 |
| Howard Frank Limited | Professional & scientific | 2004 |
| Howard Frank Services Limited | Administrative & support | 2005 |
| Howard Moule & Co Limited | Professional & scientific | 2010 |
| Howard Moule Associates LLP | | 2014 |
| Howard Waste Limited | Professional & scientific | 1999 |
| HRB Caterings Ltd | Hospitality | 2025 |
| HSH Properties Ltd | Real estate | 2017 |
| Huang's Kitchen (Enfield) Ltd | Hospitality | 2025 |
| Hub of Clinics Ltd | Other services | 2025 |
| Hudson Care Supported Living Ltd | Health & social care | 2021 |
| HUE & Machine Ltd | Information & communication | 2024 |
| Human Reproduction Group Ltd | Wholesale & retail | 2012 |
| Human Touch Limited | Administrative & support | 2000 |
| Hunter Grey Limited | Real estate | 2007 |
| Hunter House RTM Company Limited | Households | 2023 |
| Hurleys Waste Management Limited | Water & waste | 2008 |
| Hurshens Ltd | Professional & scientific | 2006 |
| Hydroni (UK) Limited | Construction | 2022 |
| Hypnodieting Ltd | Health & social care | 2009 |
| Hypogen Ltd | Information & communication | 2017 |
| I and S Construction Services Ltd | Construction | 2022 |
| I Q Security Limited | Administrative & support | 2001 |
| I&F Corporation Ltd | Administrative & support | 2014 |
| I-Msg Limited | Information & communication | 2003 |
| I-Tech 17 UK Ltd | Information & communication | 2018 |
| I.D.A. Investments Ltd | Real estate | 2017 |
| IAM Construction Ltd | Construction | 2025 |
| IAN Bailey Limited | Administrative & support | 2015 |
| IAN Mackintosh Project Management Ltd | Professional & scientific | 2013 |
| IBA - International Business Academy Limited | Education | 2009 |
| Ibem Group Limited | Professional & scientific | 2022 |
| Ibex House Ltd | Real estate | 2020 |
| Ibot Ltd | Households | 2011 |
| Ibsela Limited | Wholesale & retail | 2025 |
| Ice Property Holdings Ltd | Real estate | 2018 |
| ICM (ADI) Limited | Other services | 2003 |
| ICM Gerson Limited | Extraterritorial | 2013 |
| Icmg Relocation Limited | Extraterritorial | 2008 |
| Icontrol UK Ltd | Wholesale & retail | 2018 |
| Idea Construction Services Limited | Construction | 2006 |
| Idyllwild Consulting Limited | Construction | 2014 |
| Iglass (Worldwide) Ltd | Manufacturing | 2004 |
| Ignite Fitness Group Ltd | Arts & recreation | 2020 |