| H G Electrical Ltd | Construction | 2022 |
| H G Electrical Services Ltd | Construction | 2004 |
| H Glass and SON Limited | Financial services | 2025 |
| H H Aluminium & Building Products Ltd | Other services | 1996 |
| H H Aluminium Ltd | Other services | 2022 |
| H H Groundworks Limited | Construction | 2017 |
| H H Plant Limited | Administrative & support | 2017 |
| H H Southern Holdings Limited | Financial services | 2013 |
| H Heating and Plumbing Ltd | Construction | 2026 |
| H J B Controls Ltd | Construction | 2006 |
| H K Noodle Ltd | Hospitality | 2023 |
| H LEE Trading Limited | Information & communication | 2013 |
| H M Driving School Ltd | Education | 2023 |
| H Moore Consulting Ltd | Professional & scientific | 2023 |
| H N M Consulting Limited | Administrative & support | 2011 |
| H R Heads Limited | Extraterritorial | 2012 |
| H S Roath Ltd | Wholesale & retail | 2023 |
| H Two EAU Limited | Extraterritorial | 2013 |
| H&A Digital Services Ltd | Wholesale & retail | 2023 |
| H&A Southampton Ltd | Wholesale & retail | 2024 |
| H&B Homes (Southern) Ltd | Real estate | 2025 |
| H&C Enterprise Limited | Arts & recreation | 2011 |
| H&H Hire Ltd | Transport & logistics | 2022 |
| H&H TM Solutions Ltd | Transport & logistics | 2026 |
| H&J Metals Limited | Water & waste | 2015 |
| H&J Waste Metal Recycling Ltd | Water & waste | 2026 |
| H&Kbrownies Ltd | Hospitality | 2024 |
| H&S International Limited | Wholesale & retail | 2025 |
| H, B, C Consultancy Ltd | Professional & scientific | 2024 |
| H-Base (Services) Limited | Information & communication | 2025 |
| H-Base Limited | Information & communication | 2019 |
| H-E Technical Solutions Limited | Information & communication | 2025 |
| H. & a. Transport (Leeds) Limited | Transport & logistics | 1971 |
| H. & C. Pipe Services Limited | Manufacturing | 1996 |
| H. Brown & Sons (Engineering) Limited | Professional & scientific | 1964 |
| H. J. Baker Sulphur & Fertilizer UK Ltd | Transport & logistics | 1987 |
| H. Young (Properties) Limited | Transport & logistics | 1966 |
| H.A Electrical Services Ltd | Construction | 2022 |
| H.A Home Solutions Ltd | Real estate | 2025 |
| H.F. Luxford Investments Ltd | Extraterritorial | 2011 |
| H.I.G. Europe - Fibercore Bidco 2 Limited | Financial services | 2010 |
| H.I.G. Europe - Fibercore Bidco Limited | Professional & scientific | 2010 |
| H.J. Concepts Limited | Professional & scientific | 1988 |
| H.J. Everett (Chemist) Limited | Wholesale & retail | 1964 |
| H.M Lettings Ltd | Real estate | 2024 |
| H.Py Marine Limited | Professional & scientific | 2014 |
| H.W.E. Consulting Ltd | Construction | 2013 |
| H20 Domestic Window Cleaning Specialists Ltd | Administrative & support | 2021 |
| H2O Logistics Limited | Transport & logistics | 2017 |
| H2O Renewable Energy Ltd | Construction | 2020 |
| H2O Trade Ltd | Wholesale & retail | 2025 |
| H300 Limited | Real estate | 2011 |
| HA HA Films Limited | Administrative & support | 2011 |
| HA Management (North) Limited | Construction | 2026 |
| HA Partnership LLP | | 2023 |
| Haaelo Ltd | Wholesale & retail | 2017 |
| Habana Club Ltd | Hospitality | 2016 |
| Habawel Solutions Limited | Administrative & support | 2019 |
| Habib Ride UK Ltd | Transport & logistics | 2025 |
| Habitationem Ltd | Wholesale & retail | 2024 |
| Hackett & Holmes Ltd | Wholesale & retail | 2022 |
| Hackett Games Ltd | Manufacturing | 2020 |
| Hadi App Ltd | Information & communication | 2025 |
| Hadi Cash and Carry Ltd | Wholesale & retail | 2018 |
| Hadi Chaii Limited | Hospitality | 2020 |
| Hadi Chaii Portsmouth Limited | Hospitality | 2023 |
| Hadi Chaiiwala Limited | Hospitality | 2025 |
| Hadi S&P Ltd | Hospitality | 2025 |
| Hadley Court Freehold Limited | Households | 2024 |
| Hadrian Property Developments Ltd | Real estate | 2022 |
| Hafsa Enterprise Ltd | Wholesale & retail | 2025 |
| Hafsah Southampton Limited | Hospitality | 2024 |
| HAI BAO 8 Limited | Wholesale & retail | 2021 |
| Haidhry Security Solutions Limited | Administrative & support | 2024 |
| Haig Electrical Ltd | Manufacturing | 2018 |
| Haigate Group Ltd | Other services | 2021 |
| Haines IP Limited | Professional & scientific | 2013 |
| Hair Bare (Southern) Limited | Other services | 2015 |
| Hair Beauty Grooming UK Ltd | Wholesale & retail | 2023 |
| Hair by Emma Franzese Ltd | Other services | 2022 |
| Hair by Frankie Ltd | Other services | 2023 |
| Hair Trading (Hampshire) Ltd | Other services | 2019 |
| Hair UP by Malwina Ltd | Other services | 2019 |
| Hairbyellafagan Ltd | Other services | 2024 |
| Haircare (Woolston) Limited | Other services | 2010 |
| Haj&Ksqured Ltd | Health & social care | 2018 |
| Hakkawise Happier Beauty Ltd | Wholesale & retail | 2022 |
| Hakkawise Ltd | Wholesale & retail | 2021 |
| Hakkawise Object Beauty Ltd | Wholesale & retail | 2023 |
| Hakkawise Physis Ltd | Wholesale & retail | 2024 |
| Hakki Health Ltd | Health & social care | 2026 |
| Halal Meat Supplier Ltd | Wholesale & retail | 2025 |
| Halbac Construction Solutions Ltd | Construction | 2024 |
| Haldir Limited | Professional & scientific | 2021 |
| Hale & Gillett Investments Limited | Real estate | 1962 |
| Hales Hair Design Ltd | Other services | 2023 |
| Halfacre Consulting Ltd | Professional & scientific | 2019 |
| Halfkey Consulting Limited | Professional & scientific | 2003 |
| Halfway Inn Ltd | Hospitality | 2022 |
| Hall and Byfield Property Ltd | Hospitality | 2026 |