| H2O Heating Plumbing and GAS Services Ltd | Construction | 2024 |
| H3 Partners Limited | Professional & scientific | 2021 |
| H3 Partnership Limited | Administrative & support | 2021 |
| HA Construction Works Ltd | Construction | 2026 |
| HA Freelancing Limited | Financial services | 2017 |
| HA Global (MCR) Limited | Administrative & support | 2019 |
| HA Products Limited | Wholesale & retail | 2021 |
| HA Security Ltd | Administrative & support | 2019 |
| HA Supermart Ltd | Wholesale & retail | 2025 |
| Haadey Ltd | Wholesale & retail | 2025 |
| Haael.Co.Uk/Prim Ltd | Information & communication | 2016 |
| Haaland UK Limited | Professional & scientific | 2022 |
| Haar Limited | Wholesale & retail | 2019 |
| Haarburger Holdings Ltd | Professional & scientific | 2023 |
| HAB GOV Strategics Global Vcag Limited | Financial services | 2015 |
| Habanero West Limited | Hospitality | 2016 |
| Habberfield Training Solutions Ltd | Information & communication | 2024 |
| Habeb Mahram Ahmed Fateh Limited | Wholesale & retail | 2025 |
| Habib Mohammadi Ltd | Administrative & support | 2026 |
| Habibi Cafe Limited | Hospitality | 2023 |
| Habijabi Cardiff Limited | Hospitality | 2020 |
| Habilis Numericus Ltd | Administrative & support | 2019 |
| Habiqo Holding Limited | Real estate | 2018 |
| Habitat Support Services Ltd | Public administration | 2021 |
| Habrick Ltd | Construction | 2022 |
| Habz Ltd | Other services | 2017 |
| Hacer GOL Private Tutor Ltd | Education | 2021 |
| Hackenberg & Partner Unlimited | Extraterritorial | 2013 |
| Hacksforeasylife Ltd | Wholesale & retail | 2021 |
| Hackspace Cardiff | Other services | 2011 |
| Hadaiq Al-Mazyunah Al-Mutaqadimah for Development and Investment Ltd | Wholesale & retail | 2025 |
| Hadfield Education Ltd | Administrative & support | 2010 |
| Hadfield Holdings Limited | Construction | 2019 |
| Hadi WEN (UK) Fashion Clothing Co., Limited | Extraterritorial | 2017 |
| Hadisa Ltd | Arts & recreation | 2024 |
| Hadley Group Services Ltd | Water & waste | 2017 |
| Hadoro Management Services (UK) Limited | Financial services | 2017 |
| Hadouken Construction Ltd | Construction | 2019 |
| Hadramowt Ltd | Hospitality | 2020 |
| Hadramowt Restaurant Ltd | Hospitality | 2024 |
| Hadston Education Limited | Extraterritorial | 2013 |
| Hadston Projects Limited | Professional & scientific | 2013 |
| Haedistar Ltd | Education | 2016 |
| Haelwh Limited | Wholesale & retail | 2023 |
| Hafagear Ltd | Wholesale & retail | 2025 |
| Hafan PPS HMO CYF | Real estate | 2025 |
| Hafan PPS Ltd | Hospitality | 2024 |
| Hafan Y Ddinas Limited | Real estate | 2017 |
| Hafeez Sharief Ltd | Health & social care | 2023 |
| Hafiach Cyfyngedig | Information & communication | 2024 |
| Hafiz Muhammad Asim Farooqi Ltd | Wholesale & retail | 2026 |
| Hafiz Talha Ventures Ltd | Wholesale & retail | 2026 |
| Hafod Corporate Services Limited | Professional & scientific | 2015 |
| Hafod Cwrt Management Company Limited | Households | 1976 |
| Hafod Ganol Agri Ltd | Agriculture & fishing | 2024 |
| Hafod Homes Limited | Professional & scientific | 2006 |
| Hafod LON Limited | Administrative & support | 2009 |
| Hafren Power Limited | Energy | 2010 |
| Hafren Properties Limited | Real estate | 2018 |
| Hafsa Umar Ltd | Households | 2020 |
| Hafteco Solutions Ltd | Administrative & support | 2022 |
| Hagani Ltd | Manufacturing | 2025 |
| Hagazade Ltd | Wholesale & retail | 2025 |
| Hageiza International Holdings Ltd | Administrative & support | 2020 |
| Hagley Hillard and Co Ltd | Real estate | 2019 |
| Hagoromo UK Ltd | Wholesale & retail | 2019 |
| HAH Enterprises UK Ltd | Other services | 2017 |
| HAI KUO Ltd | Wholesale & retail | 2024 |
| Haibei Pulse Limited | Wholesale & retail | 2025 |
| Haiden Maldonado Limited | Wholesale & retail | 2019 |
| Haider Executive Travel Limited | Transport & logistics | 2025 |
| Haider Grain Ltd | Wholesale & retail | 2026 |
| Haider Supermart Ltd | Wholesale & retail | 2025 |
| Haidong Ltd | Wholesale & retail | 2025 |
| Haiimark Electrics Limited | Wholesale & retail | 2017 |
| Haileys Enterprise Ltd | Health & social care | 2026 |
| Haim Academy Limited | Health & social care | 2014 |
| Haines Engineering Solutions Limited | Professional & scientific | 2014 |
| Haines Painting & Decorating Limited | Construction | 2005 |
| Haines Watts Wales LLP | | 2009 |
| Haiping Line Co., Ltd | Wholesale & retail | 2025 |
| Hair & Moore Bolton Ltd | Other services | 2019 |
| Hair 4 U Cardiff Limited | Health & social care | 2007 |
| Hair Affairs Salon Cardiff UK Ltd | Other services | 2026 |
| Hair by Brett Limited | Other services | 2023 |
| Hair by Harry Hamilton-Shaw Ltd | Other services | 2025 |
| Hair of Towcester Limited | Education | 2015 |
| Hairflair (Cardiff) Limited | Other services | 2002 |
| Hairland Limited | Wholesale & retail | 2016 |
| Hairology REL Ltd | Other services | 2023 |
| Hairspace Wholesale Ltd | Wholesale & retail | 2021 |
| Hairun Investment Co Ltd | Financial services | 2021 |
| Hairy Grape Limited | Real estate | 2013 |
| Haisheng Hardware Co., Ltd | Administrative & support | 2020 |
| Haiwei Electrical Appliance Ltd | Wholesale & retail | 2021 |
| Haiyu Media Limited | Wholesale & retail | 2025 |
| Haiyuntrading Limited | Wholesale & retail | 2025 |
| HAJ Tours Limited | Administrative & support | 2004 |
| Hajde Ltd | Information & communication | 2021 |
| Haji Auto Repair Limited | Wholesale & retail | 2021 |