| Harprise Ltd | Real estate | 2026 |
| Harpstone Ltd | Professional & scientific | 2026 |
| Harptree Mortgages Limited | Financial services | 2025 |
| Harrian Trading Limited | Financial services | 2017 |
| Harry's Flowers Ltd | Wholesale & retail | 2015 |
| Hartwell Smith Associates Limited | Professional & scientific | 2011 |
| HAS Catering Limited | Hospitality | 2025 |
| Hastings Street Limited | Real estate | 2024 |
| Hastings Street MPG Limited | Real estate | 2024 |
| Hawk Research Limited | Professional & scientific | 2001 |
| Hawkhurst Services Ltd | Wholesale & retail | 2019 |
| Hawkshill Management Company Limited(The) | Households | 1984 |
| Hayley Rhodes TV Ltd | Information & communication | 2019 |
| Hazley Payne Ltd | Professional & scientific | 2018 |
| HB Property Venture Limited | Real estate | 2025 |
| HC Financial Ltd | Professional & scientific | 2019 |
| HCC 2015 Ltd | Arts & recreation | 2015 |
| Headland Solutions UK Limited | Information & communication | 2022 |
| Healdan Human Protection Ltd | Education | 2015 |
| Heaney Investments Limited | Financial services | 2023 |
| Heat Horizons Limited | Construction | 2025 |
| Heathview (Harpenden Management) Limited | Administrative & support | 1983 |
| HEM Wellbeing Ltd | Wholesale & retail | 2025 |
| Herbert Housing Limited | Households | 2023 |
| Here Salon Space (Hitchin) Limited | Administrative & support | 2025 |
| Heritage Assets Ltd | Real estate | 2023 |
| Hermans CGS Ltd | Professional & scientific | 2023 |
| Hermes 2000 Limited | Hospitality | 2000 |
| Hertfordshire Air Conditioning Limited | Construction | 2015 |
| Hertfordshire and Bedfordshire Fencing Company Ltd | Construction | 2026 |
| Hertfordshire Equity Release Limited | Financial services | 2020 |
| Hertfordshire Hedging Ltd | Wholesale & retail | 2013 |
| Hertfordshire Housing Conference Limited | Administrative & support | 2005 |
| Hertfordshire Insulation & Rendering Ltd | Construction | 2024 |
| Hertfordshire LTA (Sponsorship) Limited | Arts & recreation | 2007 |
| Hertfordshire LTA Limited | Arts & recreation | 1993 |
| Hertfordshire Surveyors Limited | Professional & scientific | 2009 |
| Herts Aesthetics Ltd | Other services | 2021 |
| Herts Air Conditioning Ltd | Construction | 2025 |
| Herts Home Design Ltd | Administrative & support | 2017 |
| Herts Horses and Hounds Hydrotherapy and Rehabilitation Ltd | Professional & scientific | 2018 |
| Herts Horses and Hounds Physiotherapy Ltd | Professional & scientific | 2020 |
| Herts Horses Hydrotherapy Livery Ltd | Agriculture & fishing | 2024 |
| Herts Horses Livery Ltd | Agriculture & fishing | 2024 |
| Herts Premier Decorator Ltd | Construction | 2026 |
| Herts Property Hub Ltd | Real estate | 2024 |
| Herts Structural Design Ltd | Professional & scientific | 2025 |
| Herts Tree & Garden Services Ltd | Administrative & support | 2021 |
| Herts Tutors Limited | Education | 2010 |
| HEY Stranger Pictures Ltd | Information & communication | 2025 |
| HGR Downlands Limited | Administrative & support | 2011 |
| Hhbn Solutions Ltd | Information & communication | 2017 |
| HHH Group Ltd | Hospitality | 2023 |
| Hicks Accountants Limited | Extraterritorial | 2008 |
| Hicks and Company Accountants Limited | Professional & scientific | 2015 |
| Hicks Corporate Services (PG) Limited | Extraterritorial | 2012 |
| Hicks Corporate Services Limited | Extraterritorial | 2012 |
| Hicks Group Limited | Extraterritorial | 2015 |
| Hidden Ltd | Information & communication | 2000 |
| Higgildy House Limited | Professional & scientific | 2025 |
| Highfield Advisory Ltd | Professional & scientific | 2020 |
| Highfield Development Services Ltd | Construction | 2024 |
| Highfield Oval Limited | Other services | 2019 |
| Highfields (Hemel Hempstead) Management Company Limited | Households | 2002 |
| Highgate Consulting Services Ltd | Administrative & support | 2025 |
| Highgate International Limited | Other services | 2022 |
| Highview Plumbing and Heating Limited | Construction | 2013 |
| Hillclose Management Company Limited | Households | 1998 |
| Hillingdon Animal Care Ltd | Professional & scientific | 2024 |
| Hilljgjz Consulting Ltd | Professional & scientific | 2026 |
| Hills Contemporary Consultancy Ltd | Health & social care | 2024 |
| Hillson Properties Ltd | Real estate | 2021 |
| Hilltwister (UK) Ltd | Construction | 2019 |
| HIP Warranty Company Limited | Professional & scientific | 2006 |
| Hipla Ltd | Information & communication | 2016 |
| HMD Stores Ltd | Wholesale & retail | 2021 |
| HMF Consulting Ltd | Professional & scientific | 2023 |
| Hmlz Limited | Financial services | 2023 |
| Hnworth Limited | Professional & scientific | 2024 |
| Holdene Limited | Real estate | 2016 |
| Holi Lotus Ltd | Wholesale & retail | 2021 |
| Holistic Health Group Limited | Wholesale & retail | 2019 |
| Holistic Humanity London Limited | Hospitality | 2020 |
| Hollandia Capital Partners Ltd | Financial services | 2026 |
| Holly Lodge (Harpenden) Management Company Limited | Households | 2022 |
| Hollybush Lane Management Company Limited | Households | 2016 |
| Hollybush Mews Management Company Limited | Households | 2018 |
| Holmer Green Farm Limited | Real estate | 2013 |
| Home Farm (Dane END) LLP | | 2021 |
| Home of Willa Ltd | Professional & scientific | 2023 |
| Home ST Albans | Other services | 2013 |
| Homely Spaces TOC Limited | Hospitality | 2018 |
| Homestyle Home Staging Ltd | Professional & scientific | 2020 |
| Homexe Ltd | Construction | 2021 |
| Homz Limited | Professional & scientific | 2021 |
| Honey Team Ltd | Information & communication | 2024 |
| Honneur Ltd | Manufacturing | 2025 |
| Hoole Road Limited | Real estate | 2025 |
| Horizon Equity Capital LLP | | 2010 |
| Hornal Music Ltd | Information & communication | 2024 |