| Hallingbury Sport Horse Limited | Arts & recreation | 1997 |
| Hallmark Cleaning Services Essex Ltd | Other services | 2008 |
| Hallmott Holdings Ltd | Real estate | 2021 |
| HAM 2025 Limited | Administrative & support | 2025 |
| Hangover Pals Limited | Manufacturing | 2024 |
| Harlech Media & Marketing Limited | Professional & scientific | 2014 |
| Harlow Agricultural Merchants Limited | Wholesale & retail | 1980 |
| Harrison Wheeler Limited | Professional & scientific | 2022 |
| Hatch Basements Ltd | Construction | 2025 |
| Hatch Construction Ltd | Other services | 2016 |
| Hatch Property Services Ltd | Real estate | 2024 |
| Havoc Studio Limited | Professional & scientific | 2014 |
| Hayward Investment Holdings Limited | Financial services | 2020 |
| Healing for Health Limited | Health & social care | 2012 |
| Heilong Consulting Limited | Professional & scientific | 2014 |
| Helios Developments Limited | Real estate | 2021 |
| Helixscribe Limited | Professional & scientific | 2023 |
| Hepburn Executive Consultancy Ltd | Professional & scientific | 2022 |
| Herma Distributions Limited | Transport & logistics | 2018 |
| Hertfields Events Ltd | Administrative & support | 2026 |
| Hertfields Limited | Financial services | 2026 |
| Hertfields Venues Ltd | Hospitality | 2026 |
| Hertfordshire Cleaning Services Ltd | Administrative & support | 2025 |
| Hertfordshire Installations Limited | Construction | 2017 |
| Hertfordshire Nails & Beauty Limited | Other services | 2024 |
| Herts & Essex Marquee Limited | Administrative & support | 2011 |
| Herts Car Sales Ltd | Wholesale & retail | 2023 |
| Hessian Coffee Limited | Manufacturing | 2018 |
| Highfields Henham Management Company Limited | Other services | 2016 |
| Higley Close Management Company Limited | Households | 2026 |
| Hilton Windscreens Limited | Wholesale & retail | 2013 |
| Hive Business Communications Ltd | Professional & scientific | 2002 |
| HK Wellbeing Ltd | Real estate | 2024 |
| Hktn Limited | Wholesale & retail | 2022 |
| Holmes Private Investigators Ltd | Administrative & support | 2025 |
| Hone Edwards Associates LLP | | 2001 |
| Horizon (Braintree) Limited | Real estate | 2019 |
| Hotelgreenman Ltd | Hospitality | 2024 |
| HP Boarding Limited | Other services | 2025 |
| HR Elements Limited | Administrative & support | 2010 |
| HSO Productions Limited | Arts & recreation | 2019 |
| Hugeaura Limited | Information & communication | 2005 |
| I.D.D.P. Limited | Manufacturing | 1994 |
| Icon Building Consultancy Limited | Professional & scientific | 2009 |
| Ignite Heating and Plumbing Services Ltd | Construction | 2016 |
| Impulse Racing Limited | Arts & recreation | 2009 |
| Independentskin Ltd | Other services | 2023 |
| Infiniteglass Ltd | Construction | 2018 |
| Intech Construction Ltd | Construction | 2020 |
| Inteleo UK Limited | Extraterritorial | 2017 |
| Internet Retailing Media Ltd | Information & communication | 2015 |
| Internet Retailing Media Services Limited | Information & communication | 2017 |
| Iron Rail Limited | Construction | 2016 |
| J H Utility Services Limited | Construction | 2015 |
| J. K. Character Construction Limited | Construction | 2010 |
| J.Wakefield and Sons(Builders)Limited | Construction | 1952 |
| JAC Services Limited | Wholesale & retail | 2015 |
| James Cycle Company Ltd | Manufacturing | 2000 |
| Jarman TEW Design Limited | Construction | 2008 |
| JET Flow Services Ltd | Water & waste | 2026 |
| JL Technics Limited | Transport & logistics | 2011 |
| JMB Marketing Ltd | Professional & scientific | 2021 |
| John F.Brothers Limited | Construction | 1972 |
| John Standing Art Ltd | Arts & recreation | 2026 |
| JON Harris & Co Ltd. | Professional & scientific | 2002 |
| Jonathan RL Consulting Limited | Professional & scientific | 2016 |
| JSB Property Group Ltd | Real estate | 2024 |
| JT007 Ltd | Administrative & support | 2017 |
| Julsarben Limited | Professional & scientific | 1977 |
| Juno Learning and Development Limited | Education | 2012 |
| Just Call Chris Limited | Construction | 2025 |
| Justgym Limited | Arts & recreation | 2010 |
| Justin Louis Powell Ltd | Extraterritorial | 2022 |
| JW Security Systems Limited | Administrative & support | 2008 |
| K P Property Developments Limited | Extraterritorial | 1996 |
| K. & C. Mouldings (England) Limited | Manufacturing | 1958 |
| K. & H. Electrical & Welding Contractors Limited | Manufacturing | 1985 |
| K. Carter Plant Hire Limited | Construction | 2013 |
| K. P. Despatch Limited | Professional & scientific | 1988 |
| K. P. Property Lettings LLP | | 2016 |
| Kalm Link Limited | Health & social care | 2023 |
| Katemon Court Management Company Limited | Households | 1988 |
| Kearsley Rowen Limited | Professional & scientific | 2022 |
| Kelly Brothers Construction Limited | Construction | 2001 |
| Kenron Ltd | Agriculture & fishing | 2017 |
| Kestrel Consultancy Group Ltd. | Administrative & support | 2011 |
| Kindherts Care Ltd | Health & social care | 2016 |
| Kingsmoor Publications Limited | Information & communication | 1973 |
| Kins & Folk Company Ltd | Wholesale & retail | 2024 |
| Kirtland Holdings Limited | Financial services | 2018 |
| Kitteridge ALL Sports Ltd | Arts & recreation | 2017 |
| KJP Associates Limited | Professional & scientific | 2023 |
| Koru Gyms Limited | Arts & recreation | 2014 |
| Kratos Construction Limited | Real estate | 2022 |
| Kytaali Trading Ltd | Wholesale & retail | 2022 |
| L&M Property Developments Ltd | Real estate | 2017 |
| LAB Motor Vehicle Enterprise Ltd | Wholesale & retail | 2017 |
| Lapidari Group Limited | Construction | 2021 |
| Lawrence L Pharma Limited | Professional & scientific | 2021 |
| Ledgerock Limited | Administrative & support | 2012 |