| HST CTV5 Ltd | Transport & logistics | 2023 |
| HST CTV6 Ltd | Transport & logistics | 2023 |
| HST CTV7 Ltd | Transport & logistics | 2023 |
| HST CTV8 Ltd | Transport & logistics | 2023 |
| HST CTV9 Ltd | Transport & logistics | 2023 |
| HST Global Services Limited | Transport & logistics | 2020 |
| HST Marine Holdings Limited | Transport & logistics | 2019 |
| HTG Property Limited | Real estate | 2020 |
| HTY Consultancy Ltd | Professional & scientific | 2024 |
| Hu-Tech Associates Limited | Professional & scientific | 1995 |
| Hu-Tech Experts Limited | Professional & scientific | 2018 |
| Hu-Tech Human Factors Limited | Professional & scientific | 2020 |
| Hubert Davies & SON Limited | Manufacturing | 2006 |
| Hudd Utilities Limited | Construction | 2024 |
| Hudds Food & Wines Ltd | Wholesale & retail | 2017 |
| Hudson and Clarke Group Ltd | Administrative & support | 2017 |
| Hudson Training Limited | Education | 2014 |
| Hughes Assets Limited | Real estate | 2014 |
| Hughes Household Limited | Extraterritorial | 2020 |
| Hughes Investment Properties LLP | | 2007 |
| Huha Properties Ltd | Real estate | 2017 |
| Human Advantage Coaching Limited | Professional & scientific | 2016 |
| Humble & Hustle Ltd | Wholesale & retail | 2020 |
| Humby Holdings Limited | Health & social care | 2019 |
| Hunt & Thorne Limited | Professional & scientific | 2021 |
| Huntel (Swansea) Ltd | Information & communication | 2011 |
| Huntingfield Pre-School Limited | Education | 2008 |
| Huntington Court (Swansea) Limited | Real estate | 1966 |
| Huntington Mumbles Limited | Other services | 2019 |
| Hunts View Properties Limited | Real estate | 2018 |
| Hurns Mineral Water Co. Limited | Wholesale & retail | 1966 |
| Huscarl Ltd | Administrative & support | 2023 |
| Hush Hair & Beauty (Kittle) Limited | Other services | 2003 |
| Hush Soundproofing Limited | Construction | 2016 |
| Hussa Properties Ltd | Real estate | 2024 |
| Hussain(London) Ltd | Transport & logistics | 2019 |
| Hussario Limited | Extraterritorial | 2017 |
| Hustda Holdings Limited | Hospitality | 2024 |
| Hutchby Holdings Ltd | Real estate | 2024 |
| Hutchby Kids Ltd | Real estate | 2023 |
| Hutchinson Phillips Electrical Ltd | Construction | 2017 |
| Huvo Ltd | Manufacturing | 2011 |
| HUW E. Hopkins Ltd | Health & social care | 2008 |
| HUW Griffiths Architects Ltd | Professional & scientific | 2002 |
| HUW Rees Consultants Limited | Professional & scientific | 2018 |
| HWB 360 Ltd | Professional & scientific | 2024 |
| HWC Property Services Limited | Real estate | 2026 |
| HWH Car Sales Ltd | Wholesale & retail | 2024 |
| HWH Roofing Solutions Limited | Construction | 2019 |
| HWJ Medical and Legal Services Ltd | Health & social care | 2023 |
| HWV 11 Limited | Construction | 2007 |
| Hybrid Heating Limited | Construction | 2025 |
| Hybrid Ventures Ltd | Real estate | 2005 |
| Hybridsobriety Limited | Professional & scientific | 2025 |
| Hydrachill Limited | Administrative & support | 2008 |
| Hydratech Mechanical and Electrical Ltd | Construction | 2018 |
| Hydravault Engineering Ltd | Manufacturing | 2026 |
| Hydro Steam Genie Ltd | Administrative & support | 2002 |
| Hydro Works Ltd | Construction | 2025 |
| Hydrochef Limited | Manufacturing | 2025 |
| Hydrolite Ltd | Manufacturing | 2009 |
| Hydrone Ltd | Administrative & support | 2026 |
| Hyflux Ltd | Manufacturing | 2020 |
| Hygge&Hiraeth Ltd | Professional & scientific | 2018 |
| Hygrove Aggregates Limited | Mining & quarrying | 2021 |
| Hygrove Brunel Woods Limited | Real estate | 2024 |
| Hygrove Enterprises Limited | Financial services | 2016 |
| Hygrove Holdings Limited | Construction | 2004 |
| Hygrove Homes (Swansea) Limited | Construction | 2011 |
| Hygrove Homes Limited | Extraterritorial | 2008 |
| Hygrove Property Services Limited | Construction | 2014 |
| Hypnomed Limited | Health & social care | 2017 |
| Hyport Limited | Real estate | 2022 |
| Hyppo Community Transport Ltd | Administrative & support | 2025 |
| Hyppo Hydrogen Solutions Limited | Transport & logistics | 2022 |
| HYS Clinical Ltd | Administrative & support | 2014 |
| Hyssop Clean Ltd | Administrative & support | 2022 |
| HZY Global Limited | Wholesale & retail | 2026 |
| I & a Consulting Ltd | Professional & scientific | 2024 |
| I & D Property Ltd | Real estate | 2021 |
| I & J Davies Limited | Real estate | 2023 |
| I & J Mills Limited | Other services | 2025 |
| I C Lacatus Limited | Transport & logistics | 2025 |
| I Care DOM Care Limited | Health & social care | 2008 |
| I Create Ltd | Information & communication | 2003 |
| I H T Planning Limited | Extraterritorial | 2008 |
| I J Walker Locum Limited | Professional & scientific | 2023 |
| I P Contracting and Plant Hire Limited | Administrative & support | 2017 |
| I Powell and SON Properties Ltd | Real estate | 2014 |
| I Q International Ltd | Other services | 2017 |
| I Value U Ltd | Wholesale & retail | 2022 |
| I-Design Architectural Solutions Ltd | Administrative & support | 2011 |
| I-Engineer (UK) Limited | Construction | 2007 |
| I-Photonics Ltd | Professional & scientific | 2024 |
| I. and G. Engineering Limited | Manufacturing | 1979 |
| I.C.P.S Risk Management Ltd | Professional & scientific | 2019 |
| I.F.R. & Co International Legal Services Limited | Other services | 2025 |
| IA Property Ltd | Real estate | 2025 |
| IAE Properties Limited | Real estate | 2022 |
| Iain Grant Corrosion Management Ltd | Professional & scientific | 2013 |