| Hand in Hands Ltd | Health & social care | 2011 |
| Hand Media Rigging Ltd | Construction | 2025 |
| Hand Picked Property Investments Limited | Real estate | 2020 |
| Handley Gate (Bricket Wood) Limited | Households | 2000 |
| Hands on Healthcare Solutions Ltd | Health & social care | 2018 |
| Handy Tomas Ltd | Construction | 2021 |
| Hangar One Ventures Ltd | Wholesale & retail | 2025 |
| Haniis UK Ltd | Wholesale & retail | 2023 |
| Hannah Lawrance Music Ltd | Arts & recreation | 2025 |
| Hannah Tate Aesthetics and Beauty Limited | Other services | 2022 |
| Hannibal Films Limited | Information & communication | 2015 |
| Hants & Bucks Property Group Ltd | Real estate | 2025 |
| Happy Body Project Consultants Limited | Other services | 2019 |
| Happy DMC Ltd | Administrative & support | 2020 |
| Happy Guest Properties Ltd | Hospitality | 2024 |
| Happy People Property Solutions Ltd | Real estate | 2023 |
| Happy Planet Financial Planning Limited | Financial services | 2022 |
| Happy Tiddlers Limited | Education | 2017 |
| Happy Truck Ltd | Transport & logistics | 2024 |
| Happydaizdogs Ltd | Wholesale & retail | 2023 |
| Happyfones Limited | Wholesale & retail | 2016 |
| HAPPYLIFE4EVER Limited | Wholesale & retail | 2025 |
| Happypixel Ltd. | Professional & scientific | 2021 |
| Har-Dee Properties Ltd | Real estate | 2024 |
| Harbans Logistics Ltd | Transport & logistics | 2025 |
| Harcourt Michaels Limited | Administrative & support | 2014 |
| Hardie Specialist Lighting Limited | Manufacturing | 2013 |
| Hardwick Moat Weddings Limited | Hospitality | 2022 |
| Hargreaves Plants Limited | Wholesale & retail | 2019 |
| Haris Solutions Ltd | Education | 2013 |
| Harley Specialised Construction Limited | Construction | 2016 |
| Harlo Homes Ltd | Construction | 2023 |
| Harmon Developments Limited | Construction | 2014 |
| Harmony Clinic Online Ltd | Wholesale & retail | 2025 |
| Harmony Realty Ltd | Real estate | 2024 |
| Harmony Suites Ltd | Hospitality | 2025 |
| Harmonylane Care Limited | Administrative & support | 2023 |
| Harnan Real Estate Limited | Real estate | 2018 |
| Harnek Singh Maan Limited | Transport & logistics | 2026 |
| Harold B. Paynter Limited | Agriculture & fishing | 1944 |
| Harold Lewis Limited | Hospitality | 2026 |
| HARPARS2 Ltd | Real estate | 2026 |
| Harpenden Security Systems Limited | Administrative & support | 2023 |
| Harper & Meiling Ltd | Arts & recreation | 2022 |
| Harper Plastering Ltd | Construction | 2020 |
| Harpur Wealth Management Limited | Financial services | 2015 |
| Harris Mason Investments Ltd | Financial services | 2021 |
| Harris Project Consultancy Limited | Professional & scientific | 2025 |
| Harris SS Services Ltd | Wholesale & retail | 2020 |
| Harris Structural Facades Ltd | Professional & scientific | 2016 |
| Harrison Holdings (Clophill) Limited | Professional & scientific | 2007 |
| Harrison Shortt Structural Engineers Ltd | Professional & scientific | 2015 |
| Harrison-Lynch Installations Limited | Construction | 2025 |
| Harrold Place Management Company Limited | Households | 1992 |
| Harrowden Fisheries Limited | Hospitality | 2017 |
| Harrowden Road MOT & Service Centre Ltd | Wholesale & retail | 2013 |
| Harry B.Litherland & Co. Limited | Wholesale & retail | 1970 |
| Harry Brown Butchers Limited | Wholesale & retail | 2002 |
| Harry Roberts Thatching Ltd | Construction | 2024 |
| Hart Electrical Contracting Ltd | Construction | 2013 |
| Hart Motor Vehicles Ltd | Wholesale & retail | 2024 |
| Hart Surveying Services Ltd | Professional & scientific | 2024 |
| Hart TM Ltd | Construction | 2024 |
| Hartland Management Limited | Professional & scientific | 2021 |
| Hartley and Noble Ltd | Manufacturing | 2018 |
| Harton (Civil Engineering & Road Contractors) Limited | Construction | 1978 |
| Hartwell Care Ltd | Administrative & support | 2026 |
| Hartwell Leisure Limited | Arts & recreation | 2017 |
| Harvard Logistics Ltd | Transport & logistics | 2016 |
| Harvest Consultancy Services Limited | Real estate | 2002 |
| Harvest Vision Limited | Administrative & support | 1988 |
| Harvey Adamas Limited | Construction | 1990 |
| Harvey Construction & Civils Limited | Construction | 2025 |
| Harvey Property L3 Ltd | Real estate | 2026 |
| Harville Marketing Limited | Real estate | 2001 |
| Harvlightcare Services Limited | Health & social care | 2016 |
| Haseldine Funeral Services Ltd | Other services | 2014 |
| Haseman Limited | Professional & scientific | 2015 |
| Hassan Hussain Motors Limited | Wholesale & retail | 2023 |
| Hastings Gardens (Blunham) Managing Company Limited | Professional & scientific | 2018 |
| Hatch Ventures Ltd | Wholesale & retail | 2024 |
| Hatchman Limited | Construction | 2007 |
| Hatfield Executive Aviation Limited | Transport & logistics | 1980 |
| Hathaway Gray Limited | Professional & scientific | 2012 |
| Hatim Trading Limited | Financial services | 2023 |
| Hatters Limited | Wholesale & retail | 1997 |
| Hatton Park Holdings Ltd | Construction | 2014 |
| Haulconnect Ltd | Information & communication | 2024 |
| Haus Maids Milton Keynes Ltd | Administrative & support | 2019 |
| Haus of Kairos Ltd | Wholesale & retail | 2025 |
| Haus Steps Ltd | Administrative & support | 2024 |
| Havanas Vehicle Sales Ltd | Wholesale & retail | 2012 |
| Havanna Cars Limited | Wholesale & retail | 2007 |
| Havant Foods Ltd | Hospitality | 2023 |
| Havelock Street Limited | Households | 2023 |
| Havelock Wines Limited | Professional & scientific | 1985 |
| Haven Care Living Ltd | Health & social care | 2025 |
| Haven Consulting Limited | Professional & scientific | 2026 |
| Haven Mayfair Estates Limited | Real estate | 2026 |
| Haversley Estates Limited | Real estate | 1999 |