| HGV Mechanic Ltd | Information & communication | 2023 |
| HH Aviation Services Limited | Wholesale & retail | 2022 |
| HI Foods Ltd | Manufacturing | 2024 |
| Hi-Cool Limited | Manufacturing | 2015 |
| Hi-Lo Limited | Real estate | 1981 |
| Hibbert House (Maidenhead) Management Limited | Real estate | 2017 |
| Hibbs Roofing & Building Ltd | Construction | 2025 |
| Hibdigital Ltd | Professional & scientific | 2021 |
| Hiflex UK Limited | Wholesale & retail | 2021 |
| High Mesa Ltd | Wholesale & retail | 2021 |
| High Wycombe Investment Limited | Real estate | 2020 |
| Highacre Holdings Limited | Financial services | 2018 |
| Highacre HW Ltd | Real estate | 2020 |
| Highacre One Limited | Financial services | 2018 |
| Highbarrow Holdings Limited | Administrative & support | 2016 |
| Highburgh Ltd | Information & communication | 2020 |
| Highclock Limited | Wholesale & retail | 2012 |
| Higher Purpose London Ltd | Wholesale & retail | 2026 |
| Highfield Court (Hazlemere) Management Company Limited | Real estate | 1974 |
| Highfield Land & Property Ltd | Real estate | 2020 |
| Highgain Properties Limited | Real estate | 2008 |
| Highgrounds Construction Ltd | Construction | 2025 |
| Highland Stone Ltd | Wholesale & retail | 2021 |
| Highland YAK Chew Ltd | Wholesale & retail | 2026 |
| Highlands Residents Association (Cock Lane) Limited | Hospitality | 1999 |
| Highlands Village Limited | Real estate | 1993 |
| Highstreet Corp Limited | Manufacturing | 2025 |
| Hikmah Solutions Ltd | Professional & scientific | 2023 |
| Hikvision UK Limited | Administrative & support | 2014 |
| Hill Business Limited | Water & waste | 2018 |
| Hill Rock Constructions Ltd | Construction | 2025 |
| Hillingdon Autocare Limited | Wholesale & retail | 2014 |
| Hillingdon Boiler Experts Limited | Construction | 2023 |
| Hillingdon First Limited | Real estate | 2018 |
| Hillingdon Food and Wine Ltd | Wholesale & retail | 2026 |
| Hillingdon Food Centre Limited | Hospitality | 2017 |
| Hillingdon Food Ltd | Hospitality | 2025 |
| Hillingdon Heating Limited | Construction | 2010 |
| Hillingdon Home Care Ltd | Health & social care | 2024 |
| Hillingdon Homes Estate Agents Ltd | Real estate | 2025 |
| Hillingdon Mind | Health & social care | 1995 |
| Hillingdon Narrowboats Association | Health & social care | 1991 |
| Hillingdon Pentecostal Church | Other services | 2016 |
| Hillingdon Sets Ltd | Construction | 2022 |
| Hillingdon Shopmobility | Other services | 2002 |
| Hillingdon Vision CIC | Professional & scientific | 2025 |
| Hillingdonhealthcare Ltd | Administrative & support | 2025 |
| Hillingdonmushrooms Ltd | Agriculture & fishing | 2025 |
| Hillside Roofing and Building Ltd | Construction | 2026 |
| Hilltop Care Providers Ltd | Health & social care | 2023 |
| Himalaya Property Ltd | Real estate | 2025 |
| Himmat Estates Ltd | Real estate | 2025 |
| Hind Services Limited | Professional & scientific | 2022 |
| Hinda's Healthy Hair & Skin Product Ltd | Other services | 2023 |
| Hiqma AI Ltd | Information & communication | 2024 |
| HIZ Quants Ltd | Professional & scientific | 2023 |
| HJ Dhillon Ltd. | Real estate | 2016 |
| HJR Healthcare Ltd | Health & social care | 2014 |
| HK Emea Real Estate Limited | Real estate | 2024 |
| HK European Real Estate Limited | Real estate | 2020 |
| HK Inc Ltd | Manufacturing | 2013 |
| HK Products Ltd | Wholesale & retail | 2020 |
| HK4 Properties Limited | Real estate | 2025 |
| Hkgn Accountants Limited | Professional & scientific | 2016 |
| HKL Property Developments Ltd | Real estate | 2018 |
| HKT+ Limited | Administrative & support | 2025 |
| Hkuk International PVT Ltd | Wholesale & retail | 2025 |
| HLB Europe Limited | Professional & scientific | 1991 |
| HLB International Limited | Other services | 1987 |
| Hmahdi Ltd | Health & social care | 2011 |
| HMS Car Services Ltd | Wholesale & retail | 2018 |
| HNY International Ltd | Households | 2024 |
| Hoan Kiem Food Ltd | Hospitality | 2025 |
| Hobart Road Residents Association Limited | Households | 1979 |
| Hobco Properties Limited | Real estate | 1995 |
| Hodgson Recycling Ltd | Water & waste | 2019 |
| Hoechst Celanese Plastics Limited | Manufacturing | 1963 |
| Hogarth Close Residents Management Company Limited | Real estate | 2005 |
| HOLIDAY2 Ltd | Administrative & support | 2024 |
| Holistic Kingdom Ltd | Professional & scientific | 2025 |
| Holistic-Diversity Limited | Information & communication | 2009 |
| Hollingworth Limited | Real estate | 2010 |
| Holly & DUA Limited | Hospitality | 2022 |
| Holly House Hotel Limited | Hospitality | 2017 |
| Hollybush Holdings Ltd | Real estate | 2017 |
| Holm Grove Management Limited | Households | 1999 |
| Holmoak Apartments Management Company Limited | Real estate | 1978 |
| Holt Church Limited | Construction | 2025 |
| Holy Mackerel (London) Limited | Hospitality | 2016 |
| Home Ecoearner Limited | Other services | 2023 |
| Home Elearn Limited | Real estate | 2024 |
| Home Furniture Installations Ltd | Transport & logistics | 2019 |
| Home Opti-Care Limited | Health & social care | 2010 |
| Home Storage UK Limited | Wholesale & retail | 2017 |
| Home Sweet Properties Limited | Financial services | 2024 |
| Home Swimming Limited | Arts & recreation | 2016 |
| HOMEBASE4U Limited | Wholesale & retail | 2025 |
| Homecare 110 Limited | Real estate | 2019 |
| Homerton EYE Clinic Ltd | Wholesale & retail | 2020 |
| Homes Connections Limited | Wholesale & retail | 2023 |