| Haven Mobility Ltd | Wholesale & retail | 2018 |
| Hawk Developers Limited | Construction | 2023 |
| Hawkins Petrol Service Station Limited | Wholesale & retail | 2018 |
| Hawksbrook Consulting Ltd | Administrative & support | 2023 |
| Hayward's Ltd | Construction | 2020 |
| Hazco (U.K.) Limited | Real estate | 1999 |
| Healthimprove Limited | Professional & scientific | 2025 |
| Healthy Feet ARE Happy Feet Ltd | Health & social care | 2023 |
| Heatwood Services Ltd | Manufacturing | 2025 |
| Heaven Electrical Services Limited | Construction | 2015 |
| Hello Knox Limited | Information & communication | 2016 |
| Helping Hand Foundation Ltd | Information & communication | 2023 |
| Hemisphere Capital LLP | | 2003 |
| Hempel UK Ltd. | Manufacturing | 1945 |
| Hendle Contracts Ltd | Construction | 2022 |
| Henllys Village Nursery Ltd | Education | 2016 |
| Henry Higgins Homes Limited | Real estate | 2022 |
| Heritage Business Finance Ltd | Financial services | 2025 |
| Higgs & Hiscox Ltd | Real estate | 2025 |
| High-Spec Electrical Ltd | Construction | 2024 |
| Hillier Construction Services Limited | Construction | 2021 |
| Himalayan Bites Ltd | Hospitality | 2024 |
| Hiraeth Hospitality Group Limited | Financial services | 2026 |
| Hiraeth Hospitality Limited | Hospitality | 2026 |
| Hirwaun Road Management Company Limited | Real estate | 2020 |
| Hiscox Commercial Property Ltd | Real estate | 2026 |
| Hiscox Property Holdings Ltd | Real estate | 2023 |
| Hkwh Health & Wellness Ltd | Wholesale & retail | 2025 |
| HLM Scaffolding Limited | Construction | 2020 |
| HME Consultancy Limited | Professional & scientific | 2023 |
| HMU Enterprise Limited | Wholesale & retail | 2025 |
| Hollins & More Limited | Real estate | 2023 |
| Hollywood Nails (Cwmbran) Ltd | Other services | 2022 |
| Homes Made Simple Limited | Financial services | 2016 |
| Horner Developments Wales Limited | Real estate | 2008 |
| House of Mishus Limited | Wholesale & retail | 2025 |
| Housing Bloc Limited | Real estate | 2016 |
| HP Hydraulics Ltd | Other services | 2023 |
| Hugo's Storage Limited | Other services | 2023 |
| Hugo’S Scaffolding Limited | Construction | 2023 |
| Humanifai Ltd | Professional & scientific | 2025 |
| Hustler Hoops Ltd | Wholesale & retail | 2022 |
| Hutch House Digital Ltd | Professional & scientific | 2018 |
| Hwm-Water Limited | Manufacturing | 1979 |
| Hyped Economy Limited | Wholesale & retail | 2021 |
| Hyper Thetical Games Ltd | Information & communication | 2014 |
| I AM Your Gasman Ltd | Professional & scientific | 2021 |
| I-Vision Lighting Solutions Limited | Manufacturing | 2009 |
| I.G. Landscapes Limited | Real estate | 1997 |
| IAM Digital Solutions Ltd | Information & communication | 2024 |
| Ideal Presentations Limited | Professional & scientific | 2005 |
| IG Construction Services Limited | Construction | 2020 |
| Ignis Technical Services Limited | Manufacturing | 2003 |
| IJS Accountancy Limited | Professional & scientific | 2018 |
| IL 500 Consulting Limited | Professional & scientific | 2013 |
| IM Bristol Ltd | Wholesale & retail | 2018 |
| Imperial Essences Limited | Manufacturing | 2019 |
| Inclusive Education Training and Consultancy Limited | Education | 2018 |
| Indies Designs Ltd | Professional & scientific | 2022 |
| Indies Property Company Ltd | Real estate | 2020 |
| Infinity Digital Ltd | Professional & scientific | 2025 |
| Infinity Plymstock Ltd | Wholesale & retail | 2018 |
| Ink.Print.Press Ltd | Manufacturing | 2026 |
| Innovarc Ltd | Construction | 2024 |
| Intacare Hygiene Supplies Limited | Wholesale & retail | 2010 |
| Inter Developments UK Ltd | Construction | 2007 |
| Inter Graphic Services Limited | Manufacturing | 2020 |
| Interiors ETC Limited | Extraterritorial | 2008 |
| Intershell Systems Limited | Construction | 1989 |
| Interstrand Ltd | Construction | 2021 |
| Invenio Systems Limited | Professional & scientific | 2015 |
| IR Heating and Cooling Ltd | Construction | 2024 |
| Ironmatrix Limited | Professional & scientific | 2000 |
| Ironspray Holdings Limited | Financial services | 2016 |
| Isobella Mair Bridal Ltd | Wholesale & retail | 2024 |
| Isomet (UK) Limited | Manufacturing | 1984 |
| IT Dragons Ltd | Information & communication | 2017 |
| Iven Varo Ltd | Transport & logistics | 2026 |
| J & D Evans Limited | Real estate | 2014 |
| J B Bentley Holdings Limited | Energy | 2020 |
| J Courier Ltd | Transport & logistics | 2023 |
| J H Hair Limited | Other services | 2010 |
| J N S (Cwmbran) Ltd | Hospitality | 2019 |
| J S H Letting Limited | Real estate | 2022 |
| J Tunley Contractors Limited | Construction | 2014 |
| J.C. Horseboxes Limited | Manufacturing | 2011 |
| J.D.J. Vending Services Ltd. | Administrative & support | 1997 |
| J.M. Vokes Limited | Construction | 1967 |
| J.S Electrics (JSE) Ltd | Construction | 2020 |
| Jack David Football Academy Ltd | Arts & recreation | 2016 |
| Jackson Willis Properties Ltd | Real estate | 2025 |
| Jagh Investments Co Limited | Real estate | 2017 |
| Jagh Property Investments Limited | Real estate | 2025 |
| James Bridge Property Developments Ltd | Real estate | 2024 |
| James Bridge Roofing Ltd | Construction | 2024 |
| James Brown Properties Limited | Professional & scientific | 2004 |
| Jbailey Electrical Ltd | Construction | 2018 |
| Jc&L Limited | Construction | 2026 |
| JC460 Properties Ltd | Real estate | 2019 |
| Jclad Cladding and Windows Ltd | Construction | 2021 |