| 1838 Tenby Limited | Financial services | 2023 |
| 1ST Conservatory Centre Limited | Construction | 2003 |
| 3 G'S at 44 CYF | Health & social care | 2024 |
| 3E'S Business Rescue and Development Ltd | Professional & scientific | 2025 |
| 3E'S Commercial Property Project Ltd | Construction | 2025 |
| 3E'S Supporting Business and People Ltd | Construction | 2024 |
| 3ZPT Ltd | Health & social care | 2025 |
| 4 Dewi Mind Health Matters C.I.C. | Other services | 2025 |
| 4 Wheel Detailing Ltd | Other services | 2023 |
| 4CP Group Ltd | Wholesale & retail | 2024 |
| 4DC Limited | Professional & scientific | 2023 |
| 79 Coningham Road Limited | Real estate | 2002 |
| @ BO Freelance Limited | Information & communication | 2020 |
| @ Turf Sports Limited | Arts & recreation | 2016 |
| A & a Mobile Ltd | Information & communication | 2016 |
| A & B Properties (SW) Ltd | Real estate | 2024 |
| A 1 Tachograph Services Limited | Professional & scientific | 2007 |
| A Better World Comics and Games Limited | Administrative & support | 2013 |
| A Brunt Butchers Limited | Wholesale & retail | 2006 |
| A GUY Called Minty Ltd | Wholesale & retail | 2015 |
| A L Smallholdings Ltd | Real estate | 2025 |
| A Potts Design Ltd | Professional & scientific | 2021 |
| A Roam From Home UK Ltd | Other services | 2021 |
| A S Alignments Ltd | Wholesale & retail | 2025 |
| A Squared (UK) Limited | Construction | 2018 |
| A Stephens Transport Limited | Transport & logistics | 2010 |
| A Strings Limited | Wholesale & retail | 2013 |
| A&E Plumbing and Heating South Wales Ltd | Construction | 2022 |
| A&J Shop Limited | Wholesale & retail | 2022 |
| A&K Marketplace Ltd | Wholesale & retail | 2026 |
| A&S (Ponty) Limited | Other services | 2019 |
| A. Lewis Limited | Education | 2002 |
| A.B.C. Finishing Systems Ltd | Construction | 2020 |
| A.Baul Roofing Contractors Ltd | Construction | 2020 |
| A.C. Distribution Limited | Wholesale & retail | 1997 |
| A.L. Griffiths Limited | Water & waste | 2021 |
| A1 Resourcing Limited | Administrative & support | 2023 |
| A1ZONE Ltd | Hospitality | 2023 |
| A2 Interiors Ltd | Construction | 2018 |
| A5 Hub Ltd | Real estate | 2021 |
| AAA People Training Limited | Education | 2022 |
| Aathavi Ltd | Wholesale & retail | 2024 |
| Aber-Rhondda Garages Limited | Real estate | 1972 |
| Abertillery DC Ltd | Health & social care | 2024 |
| Abhi Group Limited | Transport & logistics | 2026 |
| Abijoe Hair Ltd | Other services | 2022 |
| Abimark International Limited | Health & social care | 2024 |
| Ablos Resources UK Ltd | Real estate | 2023 |
| ABR Stage Crew Limited | Arts & recreation | 2015 |
| AC Home Installations Limited | Construction | 2014 |
| Acacia Eco Trading Limited | Administrative & support | 2017 |
| ACC Developments Ltd | Real estate | 2025 |
| Accrual World of Finance Ltd | Professional & scientific | 2023 |
| Ace Transport & Storage Limited | Transport & logistics | 2017 |
| Aces Fire Ltd | Administrative & support | 2009 |
| ACJ Drylining Limited | Construction | 2019 |
| ACM General Builder Limited | Construction | 2008 |
| Acquisition Excellence Limited | Professional & scientific | 2023 |
| ACS Employee Ownership Trustee Limited | Professional & scientific | 2024 |
| Action Hire Limited | Administrative & support | 2011 |
| Active Motion Chiropractic Limited | Health & social care | 2024 |
| Activeguard Monitoring Limited | Administrative & support | 2015 |
| AD Weston Contractors Ltd | Construction | 2026 |
| Adams DSB Limited | Real estate | 2014 |
| Adams Trading Group Ltd | Wholesale & retail | 2020 |
| Adaptive Life and Lead Ltd | Education | 2026 |
| Adaptive Vehicle Solutions Limited | Wholesale & retail | 2004 |
| ADG Estates Limited | Real estate | 2017 |
| Adhvik Enterprises Ltd | Wholesale & retail | 2018 |
| ADL Windows and Doors Ltd | Construction | 2019 |
| Advanced Carpentry Solutions Ltd | Construction | 2015 |
| Advanced Resource Management Limited | Other services | 2006 |
| Aeriogen Ltd | Professional & scientific | 2023 |
| Aero Engine Services (Holdings) Limited | Financial services | 2023 |
| AES and SON Farming Limited | Agriculture & fishing | 2021 |
| AES Plant and Sales Ltd | Construction | 2022 |
| Aesthetics 23 Limited | Other services | 2024 |
| Aeternus Education Ltd | Education | 2023 |
| Afbles Limited | Wholesale & retail | 2026 |
| Afix Konect Global Ltd | Wholesale & retail | 2025 |
| Africa Centre for Democracy and Media (Acdem) Limited | Professional & scientific | 2026 |
| Africargouk Ltd | Wholesale & retail | 2019 |
| Agricom Services Ltd | Agriculture & fishing | 2021 |
| Agrowill Green Ltd | Manufacturing | 2018 |
| AH Cardiff Limited | Real estate | 2018 |
| AI NOW Ltd | Professional & scientific | 2025 |
| AID2RECOVERYUK Limited | Health & social care | 2025 |
| AIM Security Services Ltd | Financial services | 2024 |
| Airdomes Limited | Arts & recreation | 2010 |
| Airsoft Cymru the Depot Ltd | Wholesale & retail | 2021 |
| Aitaxipontypridd Limited | Transport & logistics | 2026 |
| AJS Wood Limited | Financial services | 2016 |
| Ajtc Interiors Ltd | Construction | 2019 |
| AK Professional Consultancy Ltd | Information & communication | 2024 |
| Alaia’S Property Ltd | Real estate | 2024 |
| Alan Newland & Co Limited | Professional & scientific | 2008 |
| Alan Newland Accountancy & Taxation Ltd | Extraterritorial | 2016 |
| Albion Management (Holdings) Limited | Real estate | 2004 |
| ALL Dimensions Scaffolding Ltd | Construction | 2014 |
| ALL Wales Business School Limited | Education | 1993 |