| Happy Kids Playhouse Limited | Health & social care | 2021 |
| Hapycat Ltd | Real estate | 2025 |
| HAR NOD Ltd | Real estate | 2018 |
| Haramen Travel Ltd | Administrative & support | 2021 |
| Harbro Project Management Ltd | Professional & scientific | 2026 |
| Hard Properties Limited | Real estate | 2022 |
| Hardin Estates UK Ltd | Real estate | 2025 |
| Hardwick Court (Freehold) Limited | Real estate | 1998 |
| Hardwood Windows Ltd | Wholesale & retail | 2021 |
| Hardy Car Hire Ltd | Transport & logistics | 2021 |
| Hardy's Current Solutions Limited | Construction | 2025 |
| Hardy's Drafting Limited | Professional & scientific | 2026 |
| Haree Krishna Ltd | Wholesale & retail | 2026 |
| Harefield Motors Limited | Wholesale & retail | 2025 |
| Hari Local Store Ltd | Wholesale & retail | 2026 |
| Hari TEC Limited | Administrative & support | 2012 |
| Harirud Ltd | Transport & logistics | 2025 |
| Haris Designs Ltd | Construction | 2023 |
| Harish 19 Ltd | Professional & scientific | 2016 |
| Harish's Auto Services Limited | Wholesale & retail | 2014 |
| Harjen Properties Limited | Real estate | 2025 |
| Harkin and Harkin Limited | Financial services | 2020 |
| Harlow Estates Limited | Real estate | 2003 |
| Harmonized Systems Ltd | Construction | 2013 |
| Harmony Creations Limited | Arts & recreation | 1999 |
| Harmony DRY Cleaners Edgware Ltd | Other services | 2019 |
| Haromba Limited | Professional & scientific | 2023 |
| Haros Trust Properties Ltd | Real estate | 2022 |
| Harpsfield Property Management Limited | Households | 2008 |
| Harris Access Consulting Ltd | Professional & scientific | 2018 |
| Harris Groundworks and Construction Ltd | Hospitality | 2026 |
| Harris Kafton Limited | Professional & scientific | 2019 |
| Harris Recruitment and Management Ltd | Construction | 2024 |
| Harristino Ltd | Construction | 2020 |
| Harriswall Ltd | Real estate | 2020 |
| Harrow Discount Tyres Ltd | Wholesale & retail | 2025 |
| Harrow Foods & Wine Ltd | Wholesale & retail | 2018 |
| Harrow Investment Corporation Limited | Real estate | 2007 |
| Harrow RD Ltd | Real estate | 2021 |
| Harrow Weald Hand Car Wash Limited | Administrative & support | 2020 |
| Harshiv Enterprise Limited | Wholesale & retail | 2023 |
| Harts Marquees Limited | Administrative & support | 2021 |
| Harvard Design Consultants Limited | Professional & scientific | 2023 |
| Harvey & Company Limited | Financial services | 1993 |
| Harvey (Management Services) Limited | Administrative & support | 1981 |
| Harwood Delivery Limited | Transport & logistics | 2026 |
| Harwoods Convenience Store Limited | Wholesale & retail | 2014 |
| Hasanaj Ltd | Wholesale & retail | 2026 |
| Hasenson and Co Ltd | Real estate | 2021 |
| Hash Builders Ltd | Construction | 2015 |
| Hashemi Food Ltd | Hospitality | 2025 |
| Hashflo Ltd | Construction | 2025 |
| Hashim Consulting Ltd | Professional & scientific | 2019 |
| Hashkama Minyan at Eayc Ltd | Other services | 2022 |
| Hass Cars Ltd | Transport & logistics | 2025 |
| Hassaf Limited | Professional & scientific | 2022 |
| Hastridge Limited | Financial services | 1967 |
| Hatch END Investments Limited | Real estate | 2005 |
| Hats DMC Ltd | Transport & logistics | 2024 |
| Hatzola Edgware | Health & social care | 2013 |
| Hatzola UK Ltd | Extraterritorial | 2015 |
| Havago Trading Limited | Arts & recreation | 2025 |
| Havmoore Ltd | Real estate | 2024 |
| Hawi Healthcare Ltd | Health & social care | 2024 |
| Hawk-Eye Property Services Ltd | Real estate | 2013 |
| Hawthorn Mews Residents Company Limited | Households | 1993 |
| HAX Force Limited | Administrative & support | 2007 |
| HAY Investments Ltd | Real estate | 2019 |
| Hayastan Limited | Professional & scientific | 2015 |
| Hayes Properties (England) Limited | Real estate | 2023 |
| Haylo M & E Ltd | Administrative & support | 2014 |
| Hayter Creative Ltd | Information & communication | 2006 |
| Hazara Ltd | Wholesale & retail | 2021 |
| HBI Hospitality Limited | Real estate | 2025 |
| Hbnp Limited | Real estate | 2018 |
| HC Foundation | Health & social care | 2011 |
| HD International Limited | Information & communication | 2022 |
| Hdcdc Ltd | Households | 2022 |
| HDF Hookah Limited | Wholesale & retail | 2022 |
| HDK Hotel and Leisure Limited | Hospitality | 2015 |
| HE Beauty Center Ltd | Other services | 2019 |
| Headstone Lane (North Harrow) Management Limited | Households | 1986 |
| Heal Wellness Clinics Limited | Real estate | 2017 |
| Healease Physiotherapy Limited | Health & social care | 2026 |
| Health & Vitality Agency Limited | Administrative & support | 2021 |
| Health Foodpro UK Limited | Wholesale & retail | 2025 |
| Health Wealth Group Ltd | Health & social care | 2025 |
| Healthbit Ltd | Information & communication | 2011 |
| Healthcare for YOU Ltd | Professional & scientific | 2014 |
| Healthicon Solutions Limited | Public administration | 2023 |
| Healthy Wings Limited | Hospitality | 2018 |
| Hearcare Hub Limited | Extraterritorial | 2024 |
| Heart EYE Diagnostics Limited | Wholesale & retail | 2025 |
| Heat Cool Services Ltd | Construction | 2019 |
| Heath CUT Lodge Freehold Limited | Households | 2010 |
| Heather Court Residents' Association (Edgware) Limited | Households | 1979 |
| Heathrow JET Wash Ltd | Administrative & support | 2026 |
| Heatit Plumbing Ltd | Construction | 2019 |
| Heavenest Properties Ltd | Real estate | 2024 |
| Hectra LLP | | 2025 |