| Hearns Cleaning Services Ltd | Administrative & support | 2024 |
| Heart of Angels Care Limited | Health & social care | 2014 |
| Heartfelt Video Productions Limited | Information & communication | 2016 |
| Heartland Developments Ltd | Construction | 2025 |
| Heat Expert Ltd | Construction | 2019 |
| Heatify Ltd | Construction | 2020 |
| Heating and Electrics Ltd | Construction | 2019 |
| Heatwave Plumbing & Heating Services Ltd | Construction | 2019 |
| Heaven Day Care Ltd | Education | 2021 |
| Heckscher Piano Parts Ltd | Administrative & support | 2022 |
| Hedron Court Lease Holders Limited | Real estate | 2022 |
| Heenans Developments Limited | Construction | 2011 |
| Heinz-Glas UK Limited | Wholesale & retail | 2005 |
| Helen Bridge Consultancy Ltd | Professional & scientific | 2014 |
| Helen Pettifer Training Ltd | Professional & scientific | 2023 |
| Helena Glover Consulting Ltd | Professional & scientific | 2025 |
| Helix People Solutions Limited | Administrative & support | 2024 |
| Hellcat Interiors Ltd | Wholesale & retail | 2025 |
| Hello Scale UP Ltd | Professional & scientific | 2026 |
| Heloise Ardley Limited | Professional & scientific | 2017 |
| Helyx Secure Information Systems Limited | Information & communication | 2002 |
| HEM Group Holdings Limited | Financial services | 2019 |
| Hemel Workshops Ltd | Real estate | 2024 |
| Hemmy's Beauty Studio Ltd | Other services | 2021 |
| Hemsley and Moody Partnership Ltd | Hospitality | 2021 |
| HEN House Barns Limited | Agriculture & fishing | 2022 |
| Henley Dental Solutions Ltd | Real estate | 2021 |
| Henney’S P.M. Ltd | Construction | 2024 |
| Henry Douglas Homes Ltd | Construction | 2014 |
| Henry Gibbs (Oxon) Limited | Wholesale & retail | 1974 |
| Henry Project Management Limited | Construction | 2005 |
| Heparin Therapeutics Limited | Administrative & support | 2023 |
| Hera's Collection Ltd | Manufacturing | 2021 |
| Herisson Associates Limited | Administrative & support | 2018 |
| Heritage Delights Ltd | Wholesale & retail | 2024 |
| Heritage Meadows Properties Limited | Real estate | 2025 |
| Herne Green Limited | Information & communication | 2003 |
| Heroes Design Limited | Professional & scientific | 1982 |
| Herschel Systems Limited | Information & communication | 2012 |
| Herts Build & Maintenance Ltd | Construction | 2017 |
| Hestia Developments Limited | Construction | 2021 |
| Hevatechnologies Limited | Information & communication | 2025 |
| Hewgate Properties Investments Ltd | Real estate | 2020 |
| Hewgate Property Ltd | Administrative & support | 2017 |
| Hewitt Construction Aylesbury Ltd | Construction | 2021 |
| Hexalink Ltd | Information & communication | 2023 |
| Hexalyte Ltd | Information & communication | 2025 |
| Hexon Cars Ltd | Wholesale & retail | 2016 |
| HEY Baby 4D Aylesbury Limited | Health & social care | 2026 |
| HEY REG Ltd | Professional & scientific | 2026 |
| HF Foot Care Ltd | Health & social care | 2026 |
| HFC Billing Ltd | Hospitality | 2024 |
| Hfcommerce Ltd | Wholesale & retail | 2025 |
| HG Commercial Consulting Ltd | Professional & scientific | 2023 |
| HGB Consultancy Ltd | Professional & scientific | 2018 |
| HGV &PSV Maintenance Aylesbury Ltd | Wholesale & retail | 2025 |
| HGV Eco Services Ltd | Transport & logistics | 2022 |
| HH Autos (Aylesbury) Ltd | Wholesale & retail | 2023 |
| HH Events and Catering Ltd | Hospitality | 2026 |
| HH Prowess Limited | Administrative & support | 2018 |
| HH Ventures Ltd | Financial services | 2026 |
| Hi-Kda Ltd | Professional & scientific | 2025 |
| Hi-Pro Pressure Products Ltd | Wholesale & retail | 1998 |
| Hi-Tide Fish & Chips Limited | Wholesale & retail | 2011 |
| High Court Warrants (Essex & Hertfordshire) Ltd | Wholesale & retail | 2015 |
| High Court Warrants Limited | Administrative & support | 2015 |
| High Performance Course Limited | Extraterritorial | 2004 |
| High Performance Course UK Limited | Education | 2001 |
| High Pressure Exterior Cleaning Ltd | Administrative & support | 2024 |
| High Street Brackley Ltd | Real estate | 2015 |
| High Wycombe Painter & Decorator Ltd | Construction | 2026 |
| Highflow Heating Limited | Construction | 2016 |
| Highford Ltd | Transport & logistics | 2022 |
| Highopes Ltd | Public administration | 2024 |
| Hilary Chipping Consulting Limited | Professional & scientific | 2011 |
| Hildon House Limited | Other services | 1986 |
| Hill Carpentry & Renovations Ltd | Manufacturing | 2026 |
| Hill Farm Camping Limited | Hospitality | 2021 |
| Hill's Canine Hydrotherapy Limited | Other services | 2022 |
| Hillary Close Limited | Households | 2009 |
| Hillcrest Care and Support Ltd | Health & social care | 2026 |
| Hilltop Plumbing Ltd | Construction | 2020 |
| Hillyards Lettings Limited | Real estate | 2011 |
| Hilton Cars Limited | Wholesale & retail | 2025 |
| Hiltons Tyres Ltd | Wholesale & retail | 2025 |
| Himalaya Developments Limited | Construction | 2022 |
| Himmat Trading Ltd | Administrative & support | 2025 |
| Hinson Electrical Limited | Construction | 2016 |
| Hire a Management Consultant Limited | Professional & scientific | 2022 |
| Hire One (Radlett) Limited | Extraterritorial | 1989 |
| Hire One (St.Albans) Limited | Administrative & support | 1989 |
| Hirst Heating Services Ltd | Construction | 2018 |
| Hitch Pro Academy Ltd | Education | 2025 |
| Hitch Rigging Ltd | Construction | 2021 |
| Hitech Software Solutions Limited | Information & communication | 2008 |
| HJ Development Property Limited | Construction | 2026 |
| HJR Oils Ltd | Mining & quarrying | 2018 |
| HKB Holdings Ltd | Financial services | 2018 |
| HLR Recruit Ltd | Administrative & support | 2021 |
| HMC Utility Services Limited | Administrative & support | 2005 |