| Havard INK Ltd | Wholesale & retail | 2022 |
| Hawkeye Delivers Limited | Transport & logistics | 2020 |
| Hayley Williams Ltd | Information & communication | 2025 |
| Haystack Selection Ltd | Administrative & support | 2021 |
| Haze Brickwork Limited | Construction | 2020 |
| HB EAR Care Ltd | Health & social care | 2026 |
| HBH Automotive Limited | Wholesale & retail | 2000 |
| HD Kare Ltd | Health & social care | 2008 |
| Headstock Entertainments Ltd | Information & communication | 2015 |
| Healixir Health Ltd | Wholesale & retail | 2024 |
| Health Works (UK) Limited | Arts & recreation | 1996 |
| Heating Spares & Parts Limited | Construction | 2003 |
| Hederauk Ltd | Wholesale & retail | 2022 |
| Helen Noakes Legal Services for Children | Professional & scientific | 2004 |
| Helix Environmental Ltd | Construction | 2021 |
| Hello Beauty Ltd | Other services | 2019 |
| Hello My PA Ltd | Administrative & support | 2020 |
| Helstu Properties Ltd | Real estate | 2021 |
| Heritage Craft Carpentry Limited | Manufacturing | 2025 |
| Herlander Santana Pereira Neto Ltd | Extraterritorial | 2024 |
| HI TEK Sunbeds Ltd | Administrative & support | 1987 |
| Highsight Quality Consultants Ltd. | Professional & scientific | 2017 |
| Hill Elliott Limited | Wholesale & retail | 2025 |
| Hiraeth Camper Co Ltd | Administrative & support | 2026 |
| Hiraeth Events Limited | Hospitality | 2020 |
| Hiraeth Investments CYF | Hospitality | 2022 |
| Hive Advanced Beauty Limited | Other services | 2014 |
| HJ Spaces UK Limited | Real estate | 2025 |
| HJA Jewellery Ltd | Wholesale & retail | 2026 |
| HK Property and Investments Ltd | Financial services | 2025 |
| HM Morgan Holdings Ltd | Professional & scientific | 2025 |
| Hocl Health Limited | Professional & scientific | 2021 |
| Hoffbauer Holding Ltd | Financial services | 2022 |
| Holistic Detox Limited | Wholesale & retail | 2015 |
| Holistic Minerals Limited | Wholesale & retail | 2015 |
| Holly-Court-Contractors Limited | Administrative & support | 2019 |
| Hoplite Systems Ltd | Information & communication | 2022 |
| Horbury South West Limited | Construction | 2022 |
| Horizon Digital Media Partners LLP | | 2014 |
| Hosannah's Limited | Construction | 2019 |
| Hotchickzz Ltd | Hospitality | 2023 |
| Housemate Property Ltd | Real estate | 2024 |
| Hover Helicopters Ltd. | Transport & logistics | 2016 |
| Howells Personal Wealth Ltd | Financial services | 2022 |
| HP Construction Cleaning Limited | Administrative & support | 2024 |
| Hrls Property Ltd | Real estate | 2025 |
| Hswl (Holdings) Limited | Construction | 2023 |
| Humanitarian and Leadership Consulting Limited | Administrative & support | 2020 |
| Hutch Services Ltd | Administrative & support | 2022 |
| Hwbcymru CYF. | Professional & scientific | 2012 |
| Hydroflow Europe Limited | Manufacturing | 2013 |
| I Developments (UK) Ltd | Real estate | 2009 |
| I.C.T. Wise Limited | Information & communication | 2003 |
| I.S.T.L. Mechanical Limited | Construction | 2011 |
| I360 Ltd | Construction | 2011 |
| Ice Community Holdings Limited | Financial services | 2020 |
| Ice Foundation Limited | Education | 2015 |
| Ice Space Makers Limited | Professional & scientific | 2016 |
| Icon Barbers by Pani Ltd | Other services | 2023 |
| Iconic Autobuild Limited | Wholesale & retail | 2023 |
| Idwal Watkins Logistics Ltd | Transport & logistics | 2026 |
| Iepe Ltd | Wholesale & retail | 2023 |
| Ignite Engineering Limited | Other services | 2015 |
| Ignium Mechanical Limited | Manufacturing | 2010 |
| Iknewit Limited | Professional & scientific | 2023 |
| Image Bags Ltd | Wholesale & retail | 2026 |
| Impacting the Young Ltd | Arts & recreation | 2022 |
| Imperial Bubble Tea Ltd | Hospitality | 2023 |
| Independent Links Limited | Real estate | 2025 |
| Industrious One Ltd | Arts & recreation | 2020 |
| Inka Graphics Limited | Manufacturing | 1993 |
| Inkworks Tattoo Studio Ltd | Other services | 2023 |
| Inn on the River Limited | Hospitality | 2024 |
| INNOV8OR Solutions Limited | Professional & scientific | 2012 |
| Innovation Centre for Enterprise in Wales Limited | Real estate | 2012 |
| Insight Cost Intelligence Ltd | Professional & scientific | 2025 |
| Integral Geotechnique (Commercial) Limited | Financial services | 2017 |
| Integral Geotechnique (Holdings) Limited | Construction | 2006 |
| Integral Geotechnique (Wales) Limited | Professional & scientific | 1987 |
| Integral Geotechnique Group Ltd | Professional & scientific | 2024 |
| Integrate ERP Limited | Administrative & support | 2018 |
| Integro Protect Ltd | Wholesale & retail | 2025 |
| INTERNET4EVERYONE Limited | Wholesale & retail | 2014 |
| Interstellar Builders Limited | Manufacturing | 2024 |
| Invenix Limited | Administrative & support | 2018 |
| Investment Residential Projects Limited | Real estate | 2023 |
| Ipey Limited | Professional & scientific | 2019 |
| IRN COO Ltd | Hospitality | 2024 |
| ISB Electrical Services Ltd | Construction | 2009 |
| Islwyn Indoor Bowls Limited | Arts & recreation | 2024 |
| Islwyn Investments Limited | Real estate | 2025 |
| Issyb Limited | Professional & scientific | 2019 |
| Istadia Solutions Limited | Information & communication | 2009 |
| Italianbrasslighting Ltd | Wholesale & retail | 2025 |
| Itube Developments Ltd | Construction | 2019 |
| Ivor Jones General Builder Limited | Construction | 2015 |
| Iwba Limited | Health & social care | 2018 |
| J Bartlett Consulting Limited | Professional & scientific | 2012 |
| J G E Utilities Ltd | Construction | 2026 |
| J Galvin Transport Ltd | Transport & logistics | 2017 |