| Hollis Property Services Ltd | Households | 2024 |
| Holls UK Ltd | Professional & scientific | 2014 |
| Holly House Creative Ltd | Arts & recreation | 2022 |
| Hollywell Building Services Limited | Construction | 1993 |
| HOLM7 Ltd | Construction | 2021 |
| Holmatt Limited | Construction | 1999 |
| Holy Curls Ltd | Wholesale & retail | 2019 |
| Holywell Advisory Ltd | Extraterritorial | 2021 |
| Home Bespoke Ltd | Construction | 2020 |
| Home Changes Limited | Real estate | 2025 |
| Home Counties Couriers Limited | Extraterritorial | 2021 |
| Home Counties Logistics Limited | Transport & logistics | 2022 |
| Home Counties Security Systems (Harpenden) Limited | Administrative & support | 2019 |
| Home Focus Limited | Construction | 2004 |
| Home From Home Day Nursery Academy Ltd | Education | 2018 |
| Home Genie Group Ltd | Real estate | 2020 |
| Home Intelligence Property Services Ltd | Construction | 2024 |
| Homemill Property Ltd. | Real estate | 2017 |
| Homend UK Limited | Wholesale & retail | 2022 |
| Homeros Ltd | Hospitality | 2018 |
| Homesmith Maintenance Limited | Construction | 2017 |
| Homework Hero Limited | Education | 2025 |
| Homework Workspace Limited | Real estate | 2018 |
| Honest Architecture Ltd | Professional & scientific | 2023 |
| Hood Investments Limited | Real estate | 2006 |
| Hopkirks Ltd | Wholesale & retail | 2006 |
| Horizon Ecomm Limited | Wholesale & retail | 2025 |
| Horizon Nexus Partners Ltd | Information & communication | 2025 |
| Horizon View Estates Ltd | Real estate | 2021 |
| Horizon Wealth Group Ltd | Real estate | 2022 |
| Horse & Chains Limited | Hospitality | 2023 |
| Horwood Holdings Limited | Real estate | 2021 |
| Hose Reels Limited | Wholesale & retail | 2024 |
| Hostx Ltd | Information & communication | 2020 |
| Hot Dog Property Limited | Real estate | 2024 |
| Hotel Trade Supplies Limited | Administrative & support | 2021 |
| Hotline Plumbing & Heating Ltd | Construction | 2017 |
| Houghton Street Ventures I LP | | 2022 |
| House of Angara Ltd | Manufacturing | 2026 |
| House of Merchandise Limited | Wholesale & retail | 2022 |
| House of Pure Ltd | Other services | 2021 |
| Houseology Ltd | Information & communication | 2012 |
| Houses in Between Ltd | Professional & scientific | 2019 |
| Houznar Ltd | Wholesale & retail | 2024 |
| HOW About That Limited | Professional & scientific | 2024 |
| Howard Wallis LLP | | 2010 |
| Howberry Limited | Administrative & support | 2019 |
| HP (Soham) Limited | Construction | 2015 |
| HR Admin Limited | Administrative & support | 2012 |
| HR Katie Ltd | Administrative & support | 2014 |
| HR Transport Services Ltd | Transport & logistics | 2021 |
| HR UK PAY Ltd | Administrative & support | 2025 |
| Hrasks Ltd | Administrative & support | 2020 |
| HRG Business Solutions Limited | Professional & scientific | 2015 |
| HRV2 Medical Services Ltd | Health & social care | 2024 |
| Hsvc CP LLP | | 2022 |
| HTC Group Topco Ltd | Financial services | 2025 |
| HTH Health Limited | Health & social care | 2012 |
| Httxs Ltd | Wholesale & retail | 2016 |
| Hubbub Marketing Limited | Professional & scientific | 2022 |
| Hugral Holdings Limited | Financial services | 2022 |
| Hulbert Estates Limited | Hospitality | 2002 |
| Hull-Tullah Property Investments Limited | Real estate | 2017 |
| Human Capital Pro Limited | Administrative & support | 2026 |
| Hummingbird Innovation Limited | Professional & scientific | 2024 |
| Hungarian School ST Albans C.I.C. | Education | 2025 |
| Hunston Planning Limited | Construction | 2014 |
| Hunt Media Ltd | Information & communication | 2025 |
| Hunter Process Technology Limited | Water & waste | 1981 |
| Hunter's Mark Limited | Information & communication | 2017 |
| Hunters Gate Residents Company Limited | Households | 1992 |
| Hurlingham Capital CSD Ltd | Construction | 2020 |
| Hurlingham Capital Taunton Ltd | Construction | 2017 |
| Husain Mumen Ltd | Transport & logistics | 2026 |
| Husky Tails UK Ltd | Wholesale & retail | 2018 |
| Hutchon Electrical Contracts Ltd | Construction | 2015 |
| HW Video Ltd | Information & communication | 2020 |
| Hybrid Athlete Fitness Limited | Arts & recreation | 2025 |
| Hyde & Lyle Limited | | 1990 |
| Hyde Property Group Ltd | Real estate | 2018 |
| Hygglo Ltd | Wholesale & retail | 2015 |
| Hyman Gumbrell Research Limited | Information & communication | 2012 |
| Hynes Electrical Services Limited | Extraterritorial | 2026 |
| Hyperlabs Inc Ltd | Information & communication | 2015 |
| I & S Caglar Kebab Limited | Hospitality | 2022 |
| I AM a Web Geek Ltd | Professional & scientific | 2017 |
| I Designed Limited | Professional & scientific | 2024 |
| I Hennig & Co Limited | Wholesale & retail | 1959 |
| I SEE Creative Ltd | Arts & recreation | 2010 |
| I-Gem Associates Limited | Administrative & support | 2016 |
| I-Luminate Limited | Professional & scientific | 2015 |
| I.A.S Estates Ltd | Real estate | 2019 |
| I.E. Research Ltd | Administrative & support | 2017 |
| I.P.C. Services Limited | Manufacturing | 1981 |
| I4 Investments Ltd | Financial services | 2020 |
| IAC Outsourcing Solutions Limited | Real estate | 2012 |
| IAC Properties Holdings Ltd | Real estate | 2020 |
| Iain Rennie Hospice Services Limited | Wholesale & retail | 1995 |
| IAM Onion Limited | Information & communication | 2025 |
| IAN Biggadike Consulting Limited | Professional & scientific | 2023 |