| Greentec Solutions Limited | Construction | 2009 |
| Grip Salon Limited | Other services | 2022 |
| Groom Berkhamsted Limited | Other services | 2026 |
| Grove Design Limited | Administrative & support | 2008 |
| Grovelea Limited | Information & communication | 2022 |
| Grumpy Goot Ltd | Manufacturing | 2025 |
| Grundy Productions Limited | Professional & scientific | 2024 |
| Guardian Consulting Services Ltd | Extraterritorial | 2024 |
| Gynaecology Specialists Limited | Health & social care | 2017 |
| H G Scoot Ltd | Professional & scientific | 2018 |
| H James Limited | Professional & scientific | 2021 |
| H L S Scenery Ltd | Manufacturing | 2024 |
| H.E. Endeavour Limited | Information & communication | 2019 |
| Hadley and Rose Limited | Professional & scientific | 2024 |
| Haggaii Ltd | Financial services | 2024 |
| Hairouna Labs Ltd | Information & communication | 2026 |
| Hall Park Ltd | Professional & scientific | 2019 |
| Halo Hearing Solutions Limited | Wholesale & retail | 2020 |
| Halsey Security and Data Ltd | Administrative & support | 2020 |
| Halson Investments Limited | Real estate | 2023 |
| Hamble Rose Property Limited | Real estate | 2017 |
| Hamilltons Ltd | Wholesale & retail | 2020 |
| Hammersmith Hotel Investment Limited | Real estate | 2012 |
| Hammersmith Hotel Management Company Limited | Hospitality | 2008 |
| Hammersmith Hotel Service Company Limited | Other services | 2015 |
| Hanako Flowers Limited | Wholesale & retail | 2021 |
| Hann Graham Limited | Professional & scientific | 2014 |
| Harcombe House Limited | Real estate | 2015 |
| Harcombe House Management Company Limited | Households | 2020 |
| Hardwick Place St.Albans (Management Company) Limited | Real estate | 1988 |
| Harmony of Flavors Ltd | Hospitality | 2025 |
| Harrison Goate LLP | | 2013 |
| Harry’S Sgpt Ltd | Arts & recreation | 2026 |
| Harts Resources Ltd | Financial services | 2013 |
| Harveen Gill Associates Limited | Administrative & support | 2005 |
| Haslam Plastering Ltd | Construction | 2025 |
| Havenlux Homes Ltd | Real estate | 2025 |
| Hayden Trading Ltd | Other services | 2022 |
| Hayle Field Management Company 2 Limited | Households | 2024 |
| Haywood (L&C) Limited | Hospitality | 2019 |
| HAZ Expertise Limited | Information & communication | 2017 |
| Hazelcroft Limited | Professional & scientific | 2010 |
| Hazza Brown Ltd | Extraterritorial | 2022 |
| HCH Hill Ltd | Information & communication | 2017 |
| Headboards Ltd | Manufacturing | 2008 |
| Headlands Drive Ltd | Households | 2021 |
| Heads UP and Freer Limited | Professional & scientific | 2022 |
| Health Originals Ltd | Wholesale & retail | 2022 |
| Heand Investments Limited | Real estate | 1982 |
| Heart Care London Limited | Health & social care | 2024 |
| Heart Space Ltd | Health & social care | 2013 |
| Heatco Herts & Beds Limited | Construction | 2023 |
| Hecht Consultants Ltd | Professional & scientific | 2020 |
| Heck of a Film Service Ltd | Information & communication | 2014 |
| Hedgerow Consultancy Limited | Professional & scientific | 2021 |
| Helen Khan PR Ltd | Professional & scientific | 2022 |
| Helen Martin Limited | Manufacturing | 1995 |
| Helikon Theatre Company Ltd | Arts & recreation | 2024 |
| Hell Mountain Brewing Co. Ltd | Extraterritorial | 2014 |
| Helmfern Limited | Professional & scientific | 2001 |
| Help Educate Limited | Administrative & support | 2023 |
| Help Homes Ltd | Construction | 2018 |
| Helsprod Limited | Arts & recreation | 2013 |
| Henry Croston Films Ltd | Information & communication | 2025 |
| Heresy Consulting Limited | Professional & scientific | 2013 |
| Heron Pictures Ltd | Information & communication | 2020 |
| Heron River Limited | Real estate | 2024 |
| Hertfordshire Builders Ltd | Construction | 2022 |
| Hertfordshire Plant Ltd | Construction | 2019 |
| Herts 13 Limited | Hospitality | 2026 |
| Herts Bakehouse Ltd | Manufacturing | 2023 |
| Herts Power Services Limited | Construction | 2021 |
| Hesslegrave Company Ltd | Financial services | 2024 |
| HEW Hood Gallery Ltd | Administrative & support | 2017 |
| Hewm Partners LLP | | 2017 |
| Hexagon International (GB) Limited | Wholesale & retail | 1998 |
| HGP Design Ltd | Construction | 2021 |
| Hida Bema Ltd | Real estate | 2026 |
| Hidden Strengths (Berkhamsted) Limited | Administrative & support | 2016 |
| Higgins Mcgrath Ltd | Administrative & support | 2026 |
| High Life Treehouses Limited | Professional & scientific | 1972 |
| High Street Computers Ltd. | Wholesale & retail | 2011 |
| Highclere Financial Services Limited | Financial services | 2008 |
| Highfields (Bickington) Management Company Limited | Households | 2022 |
| Hillendale Solutions Limited | Information & communication | 2011 |
| Hillfield Procurement Limited | Professional & scientific | 2024 |
| HIO Subs Ltd | Information & communication | 2023 |
| Hjuk JOB Board Ltd | Information & communication | 2013 |
| HLJ Horseblock Limited | Financial services | 2024 |
| HNF Consulting Ltd | Professional & scientific | 2007 |
| Hobby Craft (UK) Limited | Wholesale & retail | 1993 |
| Hockeridge View Management Company Limited | Households | 2005 |
| Hockneygrey Consulting LLP | | 2024 |
| Hockneygrey Services Limited | Professional & scientific | 2024 |
| HOL Fitness Limited | Arts & recreation | 2025 |
| Holdsworth Capital Ltd | Real estate | 2018 |
| Holdsworth Developments Ltd | Real estate | 2024 |
| Holhar Limited | Information & communication | 2010 |
| Holistic Doctor Care Limited | Health & social care | 2014 |
| Holiv Ltd | Financial services | 2015 |