| Heads of the Valleys Boxing Club Limited | Arts & recreation | 2017 |
| Heads of the Valleys Performance Parts Ltd | Wholesale & retail | 2014 |
| Hearthstone Lettings Ltd | Real estate | 2025 |
| Heffernan Engineering Ltd | Construction | 2026 |
| Hek-Tek Ltd | Construction | 2017 |
| Helioforge Energy Limited | Construction | 2025 |
| Hill Property Developments Ltd | Real estate | 2023 |
| Hille Educational Products Limited | Manufacturing | 2017 |
| Hille Limited | Manufacturing | 2008 |
| Hilltop Community Sports Limited | Arts & recreation | 2009 |
| Hines Property Investment Ltd | Real estate | 2023 |
| Holls Beauty CYF | Other services | 2025 |
| Honest - Love OUR Planet Limited | Wholesale & retail | 2019 |
| Hopkins and Daughters Electrical Solutions Ltd | Professional & scientific | 2024 |
| HOV Trading Limited | Extraterritorial | 2022 |
| Hungry Doris Desserts and Cooking Sauces Limited | Manufacturing | 2022 |
| I G M Property Development Limited | Construction | 2025 |
| II Food Ltd | Hospitality | 2026 |
| IJW Design Limited | Administrative & support | 2025 |
| Ikkomkaar Ltd | Real estate | 2023 |
| IMC Associates Limited | Administrative & support | 2011 |
| Inherit Property Ltd | Real estate | 2021 |
| Innovative Support Services Ltd | Health & social care | 2023 |
| Insulation Extraction Specialists Ltd | Water & waste | 2015 |
| IPW Electrical Limited | Manufacturing | 2019 |
| Irelco Ltd | Information & communication | 2023 |
| Islwyn Management Consultants Limited | Professional & scientific | 2020 |
| J a Rogers and Sons Limited | | 1963 |
| J I Evans Interiors Limited | Other services | 2013 |
| J MAD Development Ltd | Real estate | 2024 |
| J&R Acquisitions Limited | Financial services | 2025 |
| J.P.R. Valley Ltd | Manufacturing | 2024 |
| JAC Logistics Ltd | Transport & logistics | 2025 |
| Jackson Page Snooker Ltd | Arts & recreation | 2025 |
| Jalbarc Ltd | Real estate | 2016 |
| Jalt Building Contractors Limited | Construction | 2015 |
| Jalt Real Estate Ltd | Real estate | 2025 |
| JAM PUB Brynmawr Ltd | Hospitality | 2024 |
| James Groundworks and Plant Hire Limited | Construction | 2020 |
| James Homes (Developments) Ltd | Construction | 2019 |
| Japa Vendors Global CIC | Wholesale & retail | 2025 |
| Jason Morgan Arts Ltd | Construction | 2021 |
| Jcge Properties Ltd | Real estate | 2024 |
| JCR Supermarket Ltd | Wholesale & retail | 2017 |
| JD Plumbing Heating Ltd | Construction | 2019 |
| JH - Strength Solution Ltd | Public administration | 2022 |
| Jhmapp Ltd | Administrative & support | 2022 |
| JIM Davies Beaufort Motor Company Limited | Wholesale & retail | 1959 |
| JL Vehicle Solutions Ltd | Wholesale & retail | 2021 |
| Jlen Tech Ltd | Information & communication | 2026 |
| JLN Retail Ltd | Wholesale & retail | 2024 |
| JM Logistics Ltd | Transport & logistics | 2019 |
| JME Security & Events Services Ltd | Administrative & support | 2020 |
| Jmjk Limited | Construction | 2018 |
| Jmjk Properties Ltd | Real estate | 2023 |
| Johns Travel Ltd. | Transport & logistics | 2018 |
| Jones GAS & Heating Services Ltd | Construction | 2022 |
| JP Barbering Ltd | Other services | 2019 |
| Jpkot Ltd | Wholesale & retail | 2023 |
| Juke Advisory Ltd | Professional & scientific | 2019 |
| Jupiter Electrics Ltd | Construction | 2023 |
| JW Property and Maintenance Services Limited | Construction | 2026 |
| K&A Car Wash Ltd | Other services | 2018 |
| K1 Roofing Ltd | Construction | 2023 |
| Karl James Professional Builders Ltd | Construction | 2022 |
| KB & MB Holdings Limited | Real estate | 2026 |
| Kebab Feast Limited | Hospitality | 2025 |
| Kev's Auto Repairs Limited | Wholesale & retail | 2007 |
| Khan Sons Fish Bar Ltd | Hospitality | 2025 |
| Khan Takeaway and Kebab Ltd | Hospitality | 2026 |
| Kheda Enterprises Limited | Real estate | 2008 |
| KJR Transport Limited | Transport & logistics | 2011 |
| KM Gifts & Accessories Limited | Wholesale & retail | 2016 |
| Kutz N Kurlz Limited | Other services | 2005 |
| L & M Property Services Ltd | Real estate | 2025 |
| L.C.R. Capacitors Limited | Administrative & support | 1980 |
| LA Italiano Food Ltd | Hospitality | 2024 |
| Lara Fruit and VEG Ltd | Wholesale & retail | 2025 |
| Laura DIX Aesthetics Ltd | Other services | 2020 |
| LCR Capacitors (EU) Ltd. | Manufacturing | 1992 |
| LCR Capacitors Holdings Limited | Professional & scientific | 2006 |
| LD Williams Ltd | Transport & logistics | 2019 |
| LDH Pipeline Services Ltd | Mining & quarrying | 2026 |
| Leather Notions Ltd | Manufacturing | 2014 |
| LEE Foote Properties Ltd | Real estate | 2026 |
| Leeder & Co Limited | Other services | 2019 |
| Leemafoam Ltd | Manufacturing | 2016 |
| Left of the Dial Records Limited | Administrative & support | 2017 |
| Lesco Electrical Limited | Construction | 2016 |
| Lewys Jones Carpentry & Building Ltd | Construction | 2025 |
| Lifeline Communication Services Ltd | Information & communication | 2012 |
| Lihjy Ltd | Wholesale & retail | 2026 |
| LIL Tattoo Ltd | Arts & recreation | 2025 |
| Lindemere Photography Ltd | Information & communication | 2025 |
| Line 2 Site Ltd | Construction | 2025 |
| Linkli AI Limited | Information & communication | 2025 |
| Little Wing Ecology CYF | Professional & scientific | 2021 |
| LJ & R Painting Ltd | Construction | 2024 |
| LJ Gardner Holdings Limited | Financial services | 2026 |
| LMC Consult Limited | Information & communication | 2013 |