| High Street Property Management RTM Company Limited | Households | 2025 |
| Highbourne Court Management Company Limited | Households | 2005 |
| Highbridge Laser Clinic Limited | Other services | 2019 |
| Highbury Strategy Limited | Professional & scientific | 2025 |
| Highfield Broxbourne Limited | Professional & scientific | 2023 |
| Highfields Grove Management Limited | Households | 1986 |
| Highfields of Hertingfordbury Limited | Real estate | 2021 |
| Highfix Scaffolding Solutions Ltd | Construction | 2024 |
| Highgrove Gardens Management Company Limited | Households | 2000 |
| Highways Design Alliance Limited | Professional & scientific | 2025 |
| Hijo Ltd | Hospitality | 2015 |
| Hill Lane (Southampton) Management Limited | Households | 1985 |
| Hillbrook House Management Limited | Real estate | 2015 |
| Hilltop Holdings (London) Limited | Financial services | 2025 |
| Hire Haus Limited | Professional & scientific | 2025 |
| Hivan London Ltd | Financial services | 2024 |
| HJR Capital Ltd | Real estate | 2025 |
| Hoddesdon Barbers Limited | Other services | 2026 |
| Hoddesdon Chateau Cafe Limited | Hospitality | 2017 |
| Hoddesdon Consulting Services Limited | Professional & scientific | 2023 |
| Hoddesdon Developments Ltd | Real estate | 2006 |
| Hoddesdon Energy Ltd | Energy | 2014 |
| Hoddesdon Food & Wine Limited | Wholesale & retail | 2022 |
| Hoddesdon MOT Ltd | Wholesale & retail | 2020 |
| Hoddesdon Motor Co Ltd | Wholesale & retail | 2026 |
| Hoddesdon Plant Hire Limited | Administrative & support | 1976 |
| Hoddesdon Self Storage Limited | Real estate | 2015 |
| Hollinsgate Residents Management Company Limited | Households | 2026 |
| Holly Grove Consulting Limited | Information & communication | 2021 |
| Holly Lodge (Stoneycroft) Management Company Limited | Households | 2017 |
| Hollybrook Court Management Company Limited | Households | 2013 |
| Hollywood Movie Cars Ltd | Arts & recreation | 2025 |
| Holm Court (Grove Park) Management Company Limited | Households | 1993 |
| Holmes Chapel Management Company Limited | Households | 2018 |
| Holsgrove Ltd | Real estate | 2020 |
| Home & Office Fire Extinguishers Limited | Wholesale & retail | 1979 |
| Home Choice Fireplaces Direct Ltd | Construction | 2010 |
| Home Extension Designs Ltd | Professional & scientific | 2012 |
| Home Farm Bioscience Consulting Ltd | Professional & scientific | 2019 |
| Home Hunter Agents Limited | Real estate | 2024 |
| Home Orchard Management Limited | Households | 1989 |
| Home Seekers International Ltd | Real estate | 2016 |
| Home Solutions Hub Limited | Wholesale & retail | 2015 |
| Homeone Ltd | Wholesale & retail | 2019 |
| Homestars Properties Ltd | Real estate | 2024 |
| Homestars Roofing and Building Ltd | Construction | 2025 |
| Hopkins Falshaw Limited | Professional & scientific | 2011 |
| Hopping Mill Meadow (Milford) Management Company Limited | Households | 2006 |
| Hopson Brothers Services Limited | Construction | 2011 |
| Horace Couriers Limited | Transport & logistics | 2026 |
| Horizon (Arbury L1) Management Company Limited | Households | 2006 |
| Horizon (Arbury M) Management Company Limited | Households | 2006 |
| Horizon (Arbury M1) Management Company Limited | Households | 2007 |
| Horizons (Wokingham) Management Company Limited | Households | 2005 |
| Horseshoe Court Management Co. Limited | Households | 1976 |
| Hot Radish Media Limited | Professional & scientific | 2013 |
| Hotel DU Golf Limited | Administrative & support | 2019 |
| House of Bookings Ltd. | Professional & scientific | 2020 |
| House of Hermanns (Growers) Limited | Wholesale & retail | 1980 |
| Howard Jones Consultancy Services Ltd | Professional & scientific | 2014 |
| Howlin Entertainment Limited | Arts & recreation | 2016 |
| Howlin Holdings Limited | Real estate | 2022 |
| HSA Transgroup Ltd | Transport & logistics | 2025 |
| HTS Fashion Ltd | Wholesale & retail | 2013 |
| HTS MOT Centre Limited | Wholesale & retail | 2011 |
| Hub Electronics (Group) Ltd | Financial services | 2026 |
| Hubert C. Leach (Investments) Limited | Real estate | 1963 |
| Hulse Road Management (Southampton) Company Limited | Households | 1997 |
| Humphrey & Stretton Group PLC | Professional & scientific | 2001 |
| Humphrey & Stretton Holdings Limited | Extraterritorial | 2001 |
| Humphrey & Stretton(Properties) Limited | Real estate | 1973 |
| Hunt Developments (NAH) Ltd | Real estate | 1998 |
| Hunt Developments (SAH) Ltd | Real estate | 2016 |
| Hunt Developments Group Ltd | Real estate | 1977 |
| Hunt Developments Holdings Ltd | Real estate | 2016 |
| Hunt NAH Ltd | Real estate | 2016 |
| Hunton Bridge Wharf Management Co. Limited | Households | 2006 |
| Huntsman's Gate (Puckeridge) Management Co Limited | Households | 1996 |
| Hurst Farm Mews Management Company Limited | Households | 2011 |
| Hurstwood Avenue Limited | Real estate | 2013 |
| Hurworth Park Management Company Limited | Households | 2001 |
| Hush Skin and Beauty (Royston) Limited | Other services | 2023 |
| Hyde Mews (Christchurch) Management Company Limited | Households | 2013 |
| Hygiene Holdings Limited | Financial services | 2000 |
| Hygiene Systems Limited | Wholesale & retail | 1985 |
| I & P Designs Limited | Construction | 2001 |
| I Wear Glasses Ltd | Wholesale & retail | 2009 |
| IAN E Wood Limited | Professional & scientific | 2017 |
| IBE Investments Ltd | Financial services | 2025 |
| Iberveg (UK) Limited | Wholesale & retail | 2011 |
| Iberveg Holdings Ltd | Financial services | 2025 |
| Ibroc Investments Limited | Financial services | 2019 |
| Icely Done Drinks Limited | Manufacturing | 2014 |
| ID Hoddesdon Ltd | Other services | 2024 |
| IDB Creative Limited | Information & communication | 2014 |
| IG Engineering & Maintenance Ltd | Construction | 2026 |
| Igalari Ltd | Manufacturing | 2018 |
| Ignatov Handyman Ltd | Construction | 2017 |
| Ignite Yours Ltd | Wholesale & retail | 2026 |
| Ikon Avenue (Freehold) Limited | Households | 2023 |