| H & H Property & Lettings Limited | Real estate | 2025 |
| H & J Convenience Stores Ltd | Wholesale & retail | 2024 |
| H & S Mouldings (Wales) Limited | Manufacturing | 1992 |
| H I S Group Ltd | Construction | 2024 |
| H J Vehicle Specialists Ltd | Wholesale & retail | 2024 |
| H Marwa Ltd | Real estate | 2025 |
| H R Jones & Co Limited | Administrative & support | 2006 |
| H S Bassett Holdings Limited | Financial services | 2008 |
| H&A Testing Solutions Limited | Information & communication | 2016 |
| H&H Automotives Ltd | Wholesale & retail | 2024 |
| H&K Barbers Limited | Other services | 2024 |
| H&Tal Limited | Information & communication | 2020 |
| H&W Building Limited | Construction | 2025 |
| H. Phillips Electricals Limited | Construction | 2010 |
| H.M. Thomas (Loughor) Roofers Limited | Construction | 1975 |
| H20 Pure Limited | Administrative & support | 2015 |
| H2BAY Ltd | Real estate | 2025 |
| H3 Electrical & Solar Limited | Construction | 2023 |
| H3 Facilities Management Limited | Administrative & support | 2024 |
| H3 Fire and Security Ltd | Professional & scientific | 2019 |
| H3 Group Ltd | Professional & scientific | 2009 |
| Haazura Ltd | Wholesale & retail | 2025 |
| Habitat Holding Group Limited | Health & social care | 2022 |
| Habitat Sourcing Ltd | Administrative & support | 2021 |
| Hacada Limited | Other services | 2018 |
| Hacer Developments Limited | Construction | 2006 |
| Hadfield International Marine Services Limited | Professional & scientific | 2017 |
| Haemaflow Limited | Professional & scientific | 2008 |
| Haemair Limited | Professional & scientific | 2005 |
| Hafan EK Ltd | Real estate | 2016 |
| Hafan Saff CYF | Health & social care | 2012 |
| Hafan Tywi Management Company Limited | Households | 2020 |
| Hafod Car Sales Ltd | Wholesale & retail | 2018 |
| Hafod MOT Ltd | Wholesale & retail | 2024 |
| Hafren Management Services Limited | Professional & scientific | 1995 |
| Hafren Ventures LLP | | 2008 |
| Hagan Fish Bar & Cafe Ltd | Hospitality | 2011 |
| Hagsveh Ltd | Transport & logistics | 2018 |
| Haimek Transport Limited | Transport & logistics | 2023 |
| Haimes Shepherd Limited | Real estate | 2015 |
| Haines & SON Outdoor Developments Limited | Construction | 2017 |
| Hair and Blade Limited | Other services | 2024 |
| Hair by Joanna Williams Ltd | Other services | 2013 |
| Hair by Jordan Scrine Ltd | Other services | 2024 |
| Hair by SAM Ltd | Other services | 2019 |
| Hair Matters Ltd | Other services | 2013 |
| Hairphelia Ltd | Wholesale & retail | 2023 |
| HAK (Swansea) Ltd | Hospitality | 2017 |
| Halcyon Green Ltd | Real estate | 2025 |
| Hale Heating and Plumbing Ltd | Construction | 2020 |
| Hale Heating and Renewables Ltd | Construction | 2025 |
| Hale Heating and Solar Limited | Construction | 2024 |
| Haley's Stores Limited | Wholesale & retail | 2012 |
| Halfhide Plumbing & Heating Ltd | Construction | 2015 |
| Halfyard Service Management Limited | Information & communication | 2014 |
| Hall Brothers Distribution Ltd | Transport & logistics | 2019 |
| Hall Brothers Garages Ltd | Other services | 2020 |
| Hall Brothers Transport Ltd | Transport & logistics | 2018 |
| Halle Mortgages Ltd | Financial services | 2024 |
| Hallemanuel Ltd. | Information & communication | 2017 |
| Hallett Financial Solutions Limited | Financial services | 2025 |
| Halleva Capital Limited | Financial services | 2017 |
| Halleva Consulting Limited | Financial services | 2020 |
| Halleva Mortgages Limited | Financial services | 2019 |
| Hallgrave Ltd | Construction | 2020 |
| Hallgrave Structural Engineering Ltd | Professional & scientific | 2023 |
| Halligan Meats Ltd | Wholesale & retail | 2018 |
| Halo Developments Group Ltd | Manufacturing | 2026 |
| Halo Hair Boutique Ltd | Other services | 2017 |
| Halo Modelling Ltd | Arts & recreation | 2022 |
| Halo Vapour Co Limited | Extraterritorial | 2022 |
| Haloblast and Coatings Ltd | Construction | 2023 |
| Hamber Green Limited | Administrative & support | 2001 |
| Hamilton Developments (Wales) Ltd | Construction | 2007 |
| Hamilton Owen Investments Limited | Real estate | 2019 |
| Hamiltons Contracting Services Wales Ltd | Administrative & support | 2017 |
| Hammond Energy Limited | Agriculture & fishing | 2014 |
| Hanbil Ltd | Other services | 2018 |
| Hancock and Brown (Timber) Limited | Manufacturing | 1977 |
| Hancock Carpentry Limited | Construction | 2025 |
| Handleys Properties Limited | Real estate | 2020 |
| Handmade by Bingley Kirsch Ltd | Wholesale & retail | 2020 |
| Handson Physiotherapy&Acupuncture Ltd | Health & social care | 2025 |
| HANDYMAN-24H Ltd | Construction | 2014 |
| Hanford Estates Limited | Real estate | 2005 |
| Hanford's Chemist Limited | Wholesale & retail | 2002 |
| HANGAR18MV Ltd | Hospitality | 2009 |
| Haniels Electrical Ltd | Construction | 2025 |
| Hannah K Walters Ltd | Wholesale & retail | 2024 |
| Hannah Kirkbride Ltd | Professional & scientific | 2023 |
| Hannah Mccartan Consultancy Ltd | Education | 2023 |
| Hansak Ltd | Construction | 2018 |
| Hansign Limited | Manufacturing | 2015 |
| Hanson the Clothes People Ltd | Wholesale & retail | 2022 |
| Hanson's Chefs Agency Limited | Administrative & support | 2023 |
| Hansons Restaurant Ltd | Hospitality | 2019 |
| Hanuma Kitchen and Hospitality Limited | Hospitality | 2025 |
| HAO LIN Limited | Hospitality | 2012 |
| Happily Hire After Ltd | Wholesale & retail | 2021 |
| Happy Chef Takeaway Limited | Hospitality | 2024 |