| Hardy and Co UK Ltd | Professional & scientific | 2022 |
| Hare Devdas Ltd | Wholesale & retail | 2024 |
| Hare Krishna Diamonds Limited | Wholesale & retail | 2016 |
| Hare Krishna Mission UK Limited | Other services | 2009 |
| Hare Krishna Properties Ltd | Real estate | 2025 |
| Hare Krishna Transport Ltd | Transport & logistics | 2024 |
| Hare Trading Ltd | Wholesale & retail | 2014 |
| Harefield London Limited | Financial services | 2023 |
| Harford House Limited | Professional & scientific | 2025 |
| Hari CS Ltd | Construction | 2018 |
| Hari Darshan Stores Limited | Wholesale & retail | 2022 |
| Hari Express Limited | Wholesale & retail | 2015 |
| Hari Krishna Trading Ltd | Wholesale & retail | 2023 |
| Hari Masala Zone Limited | Hospitality | 2025 |
| Hari Naam Investments Limited | Construction | 2019 |
| Hari Prasadam Limited | Wholesale & retail | 2024 |
| Hari Shil Limited | Real estate | 2024 |
| Haria & Haria Limited | Health & social care | 1975 |
| Harijyot Limited | Professional & scientific | 2008 |
| Harikrishna Drinks Ltd | Hospitality | 2021 |
| Harikrishna Foodies Limited | Hospitality | 2020 |
| Harikrishna Foods Ltd | Hospitality | 2020 |
| Harikrishna Homecare Ltd | Health & social care | 2025 |
| Harikrishna Treats Ltd | Hospitality | 2024 |
| Harikrushana Limited | Hospitality | 2025 |
| Harikrushna Healthcare Limited | Financial services | 2026 |
| Harini IT Services Ltd | Information & communication | 2011 |
| Hariom Homes Limited | Real estate | 2020 |
| Hariom Nivas Limited | Real estate | 2022 |
| Haris Quickautos Ltd | Wholesale & retail | 2024 |
| Harishwin Engineering Ltd | Construction | 2012 |
| Harishwin Real Estate Ltd | Real estate | 2018 |
| Harishwin Retail Ltd | Wholesale & retail | 2018 |
| Hariyla Consulting Limited | Health & social care | 2022 |
| Harjot Construction Ltd | Construction | 2014 |
| Harjot Property Management Ltd | Real estate | 2022 |
| Hark Care Group Ltd | Health & social care | 2022 |
| Harlequin New Homes Holdings Limited | Extraterritorial | 2021 |
| Harlequin Property Company Limited | Real estate | 1998 |
| Harley Healthcare PVT Ltd | Wholesale & retail | 2021 |
| Harley Street Audiovestibular Clinic Ltd | Health & social care | 2019 |
| Harley Street Solutions Limited | Other services | 2006 |
| Harley Tuunanen Limited | Extraterritorial | 2009 |
| Harleydoc Limited | Health & social care | 2022 |
| Harlington Manor Health Club Limited | Professional & scientific | 2006 |
| Harlowquin Creative Limited | Professional & scientific | 2025 |
| Harman HAY Publications Ltd | Education | 2020 |
| Harmanci Holding Limited | Financial services | 2022 |
| Harmon Nextech Ltd | Information & communication | 2024 |
| Harmonious Security Services Ltd | Administrative & support | 2024 |
| Harmonix Ltd | Professional & scientific | 2026 |
| Harmony Care Support Ltd | Health & social care | 2020 |
| Harmony Catering Ltd | Hospitality | 2025 |
| Harmony Kitchen Ltd | Hospitality | 2025 |
| Harmony Property Investments Ltd | Real estate | 2014 |
| Harmonymind Autism Services Ltd | Health & social care | 2023 |
| Harold Benjamin Solicitors Limited | Professional & scientific | 2019 |
| Harold Benjamin Trust Corporation Limited | Professional & scientific | 2021 |
| Haroon Amjad Ltd | Health & social care | 2023 |
| Haroon Rice Traders UK Ltd | Professional & scientific | 2025 |
| Harp Investments Limited | Real estate | 2005 |
| Harp Island Village NO. 1 Residents Company Limited | Households | 1986 |
| Harp Island Village NO. 2 Residents Company Limited | Households | 1986 |
| Harpenden Modular Construction Ltd | Construction | 2025 |
| Harpers of London Limited | Other services | 2007 |
| Harrietco Ltd | Professional & scientific | 2026 |
| Harrington Maintenance Company Limited | Construction | 2022 |
| Harris Assets Limited | Real estate | 2014 |
| Harris Design Limited | Information & communication | 2015 |
| Harrison Haulage Limited | Transport & logistics | 2018 |
| Harrison HQ Ltd | Real estate | 2025 |
| Harrisons Electrical Solutions Limited | Other services | 2015 |
| Harrisons Properties Limited | Real estate | 1995 |
| Harrogate Hand Clinic Limited | Health & social care | 2019 |
| Harrovian Business Village Management Limited | Real estate | 1991 |
| Harrovian Hotels Ltd | Hospitality | 2025 |
| Harrow 5 Star Tyres & Services Ltd | Wholesale & retail | 2024 |
| Harrow Association of Disabled People | Other services | 2000 |
| Harrow Association of Somali Voluntary Organisations Limited | Health & social care | 2005 |
| Harrow Auto & Tyres Ltd | Wholesale & retail | 2025 |
| Harrow Autos Ltd | Wholesale & retail | 2026 |
| Harrow Banquete Hall Ltd | Hospitality | 2025 |
| Harrow Barber Limited | Other services | 2022 |
| Harrow Borough Football Club Limited | Arts & recreation | 1937 |
| Harrow Bowls Club Limited | Arts & recreation | 2016 |
| Harrow Breakers Limited | Wholesale & retail | 2017 |
| Harrow Budget Limited | Wholesale & retail | 2009 |
| Harrow Budget MOT Limited | Wholesale & retail | 2026 |
| Harrow Cafe Limited | Wholesale & retail | 2018 |
| Harrow Car Care Limited | Wholesale & retail | 2022 |
| Harrow Car Wash & Garage Ltd | Wholesale & retail | 2015 |
| Harrow Carers | Health & social care | 1997 |
| Harrow Carers Homecare Limited | Health & social care | 2017 |
| Harrow Citizens Advice Bureaux Service Limited | Health & social care | 1995 |
| Harrow Community Transport | Transport & logistics | 2005 |
| Harrow Development Excellence Ltd | Real estate | 2025 |
| Harrow District Masonic Council Limited | Hospitality | 1948 |
| Harrow Dreams Ltd | Wholesale & retail | 2025 |
| Harrow Driving School Ltd | Education | 2024 |
| Harrow Dwellings Limited | Real estate | 2016 |