| Grosvenor Financial Nominees Limited | Extraterritorial | 1984 |
| Groundwork East | Professional & scientific | 1985 |
| Grove Mill Developments Limited | Households | 2003 |
| Grove Road Maintenance Company Limited | Real estate | 1988 |
| Gsr.Transport Limited | Transport & logistics | 2008 |
| GT UK Estates Ltd | Professional & scientific | 1992 |
| Gtec Group Limited | Administrative & support | 2003 |
| Guardian Consultancy Services Limited | Construction | 2003 |
| Guardian of Devotion Trust Ltd | Other services | 2019 |
| Guybrook Limited | | 1980 |
| Guys Express Haulage Limited | Information & communication | 2005 |
| GY Associates Limited | Professional & scientific | 2002 |
| H & H Elite Catering Limited | Hospitality | 2003 |
| H & H London Investments Ltd | Real estate | 2023 |
| H Mapplebeck & Sons Limited | Professional & scientific | 2003 |
| H&C Business Services Limited | Professional & scientific | 2004 |
| H. Acik Services Ltd | Professional & scientific | 2012 |
| H. G. Construction (Holdings) Limited | Professional & scientific | 2000 |
| H.E. Stringer (Exports) Limited | Manufacturing | 1962 |
| H.E.Stringer Limited | Professional & scientific | 1955 |
| H.R.H. Logistics Limited | Transport & logistics | 2003 |
| Habitome Properties Ltd | Real estate | 2024 |
| Hadaw Productions and Investments Ltd. | Other services | 2006 |
| Haden International Limited | Wholesale & retail | 1948 |
| Hades Consulting Limited | Professional & scientific | 1997 |
| Hadley GH Ltd | Financial services | 2024 |
| Hadley RM Ltd | Real estate | 2024 |
| Haggerston Castle Limited | Hospitality | 1969 |
| Hair 202 (N2) Ltd | Other services | 2022 |
| Hair 202 Ltd | Other services | 2024 |
| Hair DE Luxe Limited | Other services | 2013 |
| Hair Raizin Sales Ltd | Administrative & support | 2006 |
| Hall Bros. (Lifting Gear) Limited | Manufacturing | 1957 |
| Halsey Masonic Hall,Watford,Limited | Other services | 1925 |
| Hamilton Abercorn Hotels Ltd | Real estate | 2024 |
| Hamlohh Holdings | Financial services | 2021 |
| Hammersmith Property Co Limited | Real estate | 2000 |
| Hanbury Home Improvements Limited | Administrative & support | 2003 |
| Handog Holdings Ltd | Financial services | 2024 |
| Hanlar Limited | Hospitality | 2026 |
| Hannah Azizollah Limited | Health & social care | 2003 |
| Happy Vanilla UK Ltd | Wholesale & retail | 2024 |
| Harbenpark Limited | Wholesale & retail | 1989 |
| Harbourline Holdings Ltd | Professional & scientific | 2024 |
| Haria Property Investments Ltd | Real estate | 2020 |
| Harlequin Direct Limited | Administrative & support | 1996 |
| Harlington Stays Ltd | Households | 2023 |
| Harman Software Associates Limited | Information & communication | 1998 |
| Harpenden Property Ltd. | Real estate | 2004 |
| Hasca Limited | Administrative & support | 2004 |
| Hatfield Bowls Club Ltd | Arts & recreation | 1987 |
| Hatherley Limited | Real estate | 1998 |
| Haus Proud North London Ltd | Real estate | 2024 |
| Havant Properties Ltd | Real estate | 2019 |
| Haven Leisure Limited | Hospitality | 1985 |
| Hawthorn Farm Management Company Limited | Real estate | 2006 |
| Hayley Lehmann Limited | Other services | 2003 |
| Hayter Holdings Limited | Financial services | 2004 |
| Hayyat Investments Ltd | Real estate | 2021 |
| Hazeldene Services Limited | Real estate | 2002 |
| Hazelton Meadow Management Company Limited | Households | 2026 |
| Hbd-Consultancy Limited | Construction | 1999 |
| Headstart Fencing (Supplies) Limited | Wholesale & retail | 2002 |
| Healthy Industrial Design (H.I.D.) Limited | Professional & scientific | 1977 |
| Heat Outdoors Limited | Administrative & support | 2007 |
| Heatec (Herts) LLP | | 2003 |
| Heath END Court Management Company Limited | Households | 2004 |
| Heathfield Homes Construction Limited | Extraterritorial | 1986 |
| Heathfield Homes Limited | Construction | 1969 |
| Heavens Above Beauty Limited | Other services | 2002 |
| Helen Broomby Associates Limited | Real estate | 2004 |
| Helen’S KITCHEN06 Limited | Hospitality | 2023 |
| Hellenic Music Centre Limited | Information & communication | 1998 |
| Helston Securities Limited | Real estate | 1992 |
| Hemel Hempstead Limited | Other services | 2000 |
| Hemel Hempstead Storage Limited | Real estate | 2002 |
| Hemel Marina Limited | Manufacturing | 2021 |
| Hercules Plumbing and Heating Limited | Construction | 2005 |
| Heritage Carpentry Contractors Limited | Construction | 1998 |
| Heritage House (Aldeburgh) Limited | Households | 1992 |
| Hermano Holdings Ltd | Real estate | 2022 |
| Hertford Roofing Limited | Construction | 2007 |
| Hertfordshire Building Preservation Trust Limited | Arts & recreation | 1963 |
| Hertfordshire Display PLC | Manufacturing | 1976 |
| Hertfordshire Football Association Limited | Arts & recreation | 1998 |
| Hertfordshire Property Services Limited | Real estate | 1999 |
| Herts Bathroom Centre Limited | Construction | 1998 |
| Herts Home Carers Ltd | Health & social care | 2018 |
| Herts Visionplus Limited | Wholesale & retail | 1990 |
| Hertsmere Jewish Primary School Trust | Education | 1997 |
| Hevac Sales Ltd | Construction | 2003 |
| Hewes Security Limited | Administrative & support | 2001 |
| Hewitt Consulting Limited | Professional & scientific | 2003 |
| Hewitts Investments Limited | Real estate | 2001 |
| Hewitts Retail Limited | Wholesale & retail | 2001 |
| HG Construction Limited | Construction | 1982 |
| Hi-Tech Communications Limited | Information & communication | 1993 |
| High Voltage Electrical Services Limited | Construction | 2007 |
| Highclere (City) Limited | Information & communication | 1996 |
| Highway Heating & Plumbing Supplies Limited | Wholesale & retail | 2002 |