| 180 Degrees Consulting Leeds CIC | Professional & scientific | 2025 |
| 2MUCH Link Limited | Arts & recreation | 2025 |
| 3 Peaks Developments Ltd | Construction | 2021 |
| 3DCADWALES Limited | Information & communication | 2013 |
| 3W Properties Limited | Real estate | 2025 |
| 46R Ltd | Hospitality | 2026 |
| 4JNG Properties Limited | Real estate | 2011 |
| 4U Rail & Civil Ltd | Professional & scientific | 2016 |
| 55THELEMENT Ltd | Administrative & support | 2025 |
| A & a Construction and Rail Limited | Construction | 2019 |
| A & D Bricklaying Services Ltd | Construction | 2018 |
| A & S Fire Safety Ltd. | Professional & scientific | 2017 |
| A B C Domestic Repairs Limited | Manufacturing | 2002 |
| A J Estebanez Services Limited | Construction | 2019 |
| A J Roller Shutter Doors Limited | Manufacturing | 2018 |
| A Phillips Enforcement Ltd | Other services | 2025 |
| A Power Medical Ltd | Health & social care | 2023 |
| A T Pharma Solutions Limited | Health & social care | 2015 |
| A&K's Clearance Ltd | Wholesale & retail | 2025 |
| A&L Taxis (Pontypridd) Ltd | Transport & logistics | 2023 |
| A-Spec Electrical Ltd | Construction | 2019 |
| A.L.F. Electrical Management Limited | Construction | 2018 |
| A.M.E Electrical Limited | Administrative & support | 2016 |
| A1 PPE & Cleaning Services Limited | Wholesale & retail | 2025 |
| A1 Rail & Civils Limited | Administrative & support | 2020 |
| A1 Zero Carbon Ltd | Construction | 2024 |
| Aabb Limited | Transport & logistics | 2025 |
| ABA Trans Ltd | Transport & logistics | 2025 |
| ABC Domestic Supplies Limited | Wholesale & retail | 2010 |
| Aberdare Trading Cards Limited | Wholesale & retail | 2026 |
| Abox Storage Solutions Limited | Other services | 2008 |
| AC1 Properties Limited | Real estate | 2026 |
| Accord Professional Services Limited | Professional & scientific | 2019 |
| Accounting Solutions (South Wales) Limited | Professional & scientific | 2010 |
| Ace Building Contractors (Wales) Limited | Construction | 2002 |
| Ace Leisure Ltd | Hospitality | 2021 |
| Ace Property Investments Limited | Construction | 2006 |
| ACP Electrical Limited | Construction | 2019 |
| Action Care Services Ltd | Administrative & support | 2019 |
| Adaptive Design Engineering Ltd | Professional & scientific | 2020 |
| Adfercymru Ltd | Construction | 2021 |
| Adlam Drylining and Plastering Limited | Construction | 2020 |
| Adlamwilliamsproperty Ltd | Real estate | 2025 |
| ADS Railtech Limited | Construction | 2018 |
| Advance Your Game Ltd | Education | 2026 |
| Advanced Gate-Tec Ltd | Manufacturing | 2015 |
| Aeroplus Limited | Manufacturing | 2019 |
| AG Smart Shops Limited | Wholesale & retail | 2025 |
| Aileni Ltd | Education | 2024 |
| Ainsley Construction Limited | Construction | 2005 |
| AJ Consultants Connect Ltd | Professional & scientific | 2025 |
| AJL Railresourcing Ltd | Construction | 2016 |
| Ajlrailandcivils Ltd | Construction | 2022 |
| AJM Grant Services Limited | Professional & scientific | 2009 |
| AK Cash & Carry Ltd | Wholesale & retail | 2013 |
| AK Thomas LLP | | 2026 |
| Albert & Flaherty Limited | Construction | 2004 |
| Alfarichi Limited | Information & communication | 2009 |
| Aliyans Kitchen Ltd | Hospitality | 2026 |
| Alkel Properties Ltd | Real estate | 2018 |
| ALL Round Energy Solutions Ltd | Construction | 2012 |
| ALL Secure Doors Ltd. | Construction | 2021 |
| Allbelt (South Wales) Ltd | Manufacturing | 2010 |
| Allen Holdings Limited | Construction | 1981 |
| Alphaverse Consultants Private Limited | Wholesale & retail | 2024 |
| Alrod Limited | Manufacturing | 1986 |
| Amanda King Education Support Ltd | Education | 2011 |
| Amber & Ruby Developments Limited | Construction | 2017 |
| AMH Construction Services (Wales) Limited | Construction | 2019 |
| AMH Resources Ltd | Financial services | 2023 |
| AMJ Healthcare Ltd | Health & social care | 2024 |
| AMJ Properties Group Limited | Real estate | 2022 |
| Amlo Engineering Surveying Limited | Construction | 2017 |
| Amlo Holdings Ltd | Financial services | 2023 |
| Andrew Jones Safety Ltd | Construction | 2011 |
| Anew Advisory Services Ltd | Professional & scientific | 2024 |
| Anew Energy Limited | Construction | 2026 |
| Angeni Support Ltd | Health & social care | 2020 |
| Animap UK Limited | Information & communication | 2026 |
| Anncal Property Ltd | Real estate | 2024 |
| Annette Callaghan Limited | Professional & scientific | 2014 |
| Anngwen Properties Limited | Real estate | 2025 |
| ANP at KLA Medical Limited | Health & social care | 2024 |
| Anvil Electrical and Security Ltd | Construction | 2023 |
| AOB Consulting Ltd | Professional & scientific | 2025 |
| Apex Construction South Wales Ltd | Construction | 2025 |
| Apex-Infrastructure Solutions Ltd | Construction | 2026 |
| Apollo Servicing & Repairs (Bicester) Limited | Wholesale & retail | 2024 |
| Apollo Servicing & Repairs Limited | Wholesale & retail | 2023 |
| Apollo Sports & Performance Limited | Wholesale & retail | 2020 |
| Applied Architecture Limited | Professional & scientific | 2005 |
| Apptoria Software Ltd | Wholesale & retail | 2023 |
| ARA Medical Services Limited | Health & social care | 2023 |
| Aras Transport Services Ltd | Transport & logistics | 2024 |
| ARC Financial Bookkeeping & Accountancy Ltd | Professional & scientific | 2023 |
| AREA51 Playcentre Merthyr Ltd | Arts & recreation | 2022 |
| Aris Networks Ltd | Information & communication | 2022 |
| Armorizex Ltd | Administrative & support | 2023 |
| Arquius Limited | Wholesale & retail | 2017 |
| ASC Info Center Limited | Information & communication | 2025 |