| 10 10 Sports Coaching & Consultancy Ltd | Education | 2023 |
| 16 and 18 High Street Abertridwr Limited | Administrative & support | 2007 |
| 1ST Choice Fire Protection (Wales) Ltd | Manufacturing | 2008 |
| 1ST Class Hygiene Limited | Other services | 2007 |
| 2 EXP Financial Services Limited | Financial services | 2016 |
| 3 Blinds,Nice! Limited | Wholesale & retail | 2005 |
| 3 Core AV Ltd | Information & communication | 2018 |
| 3D Development Ltd | Construction | 2026 |
| 4 Everyoungfitness CIC | Health & social care | 2024 |
| 7336 Limited | Financial services | 2023 |
| A & B Marble Limited | Manufacturing | 2020 |
| A Approved Cleaning Services Ltd | Administrative & support | 2017 |
| A B Builders (Caerphilly) Ltd | Construction | 2020 |
| A Bite of Life Limited | Health & social care | 2020 |
| A H Forestry Limited | Agriculture & fishing | 2022 |
| A N Wills Ltd | Other services | 2014 |
| A R Drainage Solutions Ltd | Water & waste | 2013 |
| A R Steelwork Ltd | Manufacturing | 2014 |
| A Reese Electrical Ltd | Construction | 2015 |
| A Sign 4 U Ltd | Construction | 2013 |
| A Star Waste Solutions Ltd | Water & waste | 2025 |
| A&K Leisure Holdings Ltd | Hospitality | 2019 |
| A-D-L Catering Ltd | Hospitality | 2016 |
| A.O Landscaping Ltd | Administrative & support | 2020 |
| A.S.J. Couriers Limited | Transport & logistics | 2026 |
| A1 Holdings (Cardiff) Ltd | Financial services | 2016 |
| A2B Contracting Services Limited | Construction | 2019 |
| AA Hire Ltd | Agriculture & fishing | 2021 |
| AB Fencing & Gates Ltd | Manufacturing | 2023 |
| AB Metal Fabricators Ltd | Manufacturing | 2020 |
| Abbeystreet Limited | Information & communication | 1996 |
| Aber Mini Market Ltd | Households | 2025 |
| Abiani Ltd | Wholesale & retail | 2024 |
| Abigail's Day Nurseries Employee Ownership Trustee Limited | Professional & scientific | 2022 |
| Abigail's Day Nurseries Limited | Other services | 2012 |
| Absolute Associates Limited | Construction | 2002 |
| AC Easy Ltd | Construction | 2016 |
| AC Software Ltd | Professional & scientific | 2013 |
| Academa Talent Ltd | Information & communication | 2018 |
| Accelerate Recruitment Consultancy Ltd | Administrative & support | 2022 |
| Ace Catering Services Ltd | Hospitality | 2023 |
| Ace Cooling Solutions Ltd | Construction | 2015 |
| Achieve With Abbie Ltd | Arts & recreation | 2025 |
| Aclarar Ltd | Information & communication | 2010 |
| Acme Production Services Ltd | Transport & logistics | 1999 |
| Acorn Digital Services Limited | Information & communication | 2024 |
| Acorns Bakery Limited | Hospitality | 2002 |
| Activwearlgb Ltd | Wholesale & retail | 2018 |
| ACW Freelance Ltd | Transport & logistics | 2023 |
| ACW Funerals Limited | Other services | 2021 |
| AD Commercial Mortgages & Development Finance Ltd | Financial services | 2025 |
| Ad@M Ltd | Manufacturing | 2020 |
| Adarsans Ltd | Wholesale & retail | 2014 |
| Addis Properties Limited | Real estate | 2024 |
| Addysg Hiraeth Ltd | Education | 2017 |
| Adrian Harries Ltd | Wholesale & retail | 2021 |
| Adventura Global Ltd | Wholesale & retail | 2023 |
| Adventurer's Attic Ltd | Wholesale & retail | 2023 |
| Aesthetic Rejuvenation Therapies Limited | Other services | 2020 |
| AFM (SW) Limited | Professional & scientific | 2015 |
| Afrizon Bespoke Services (ABS) CIC | Health & social care | 2023 |
| AFT Consultancy Limited | Construction | 2024 |
| AFT Corporate Facilities Ltd | Professional & scientific | 2013 |
| AFT Group (Wales) Ltd | Manufacturing | 2012 |
| AG Baker Property Management Ltd | Real estate | 2024 |
| Agile Cloud Development Limited | Information & communication | 2018 |
| Agilis Sportswear Limited | Wholesale & retail | 2021 |
| AGJ Accountants Limited | Professional & scientific | 2016 |
| Agora Handicrafts Ltd | Wholesale & retail | 2024 |
| Agriculture Union Ltd | Wholesale & retail | 2024 |
| AH Hair & Beauty Ltd | Other services | 2026 |
| AIO Developments Limited | Real estate | 2021 |
| Air Conditioning Systems Wales Limited | Construction | 2005 |
| Air Control Ventilation Limited | Manufacturing | 2013 |
| AJ Property Services & Maintenance Limited | Construction | 2024 |
| AJC Electrical Solutions Limited | Construction | 2013 |
| AJM Asset Management Ltd | Financial services | 2018 |
| AJW Builders (South Wales) Ltd | Construction | 2024 |
| Alan Hill Window Systems Limited | Construction | 2014 |
| ALB Print Services Limited | Wholesale & retail | 1999 |
| Alex Underhill Carpentry Ltd | Construction | 2026 |
| Alexercise Ltd | Arts & recreation | 2018 |
| Alihaus Ltd | Manufacturing | 2018 |
| Alive Denim Limited | Wholesale & retail | 2016 |
| ALL Seasons Blinds Limited | Manufacturing | 2002 |
| Allanda Limited | Professional & scientific | 2006 |
| Allied Buildings Limited | Real estate | 2022 |
| Alpha Eagles Ltd | Information & communication | 2024 |
| Altano Group PC | | 2018 |
| Altralaw Ltd | Professional & scientific | 2018 |
| Alvari Honey Ltd | Wholesale & retail | 2023 |
| AMA Ingredients Limited | Manufacturing | 2023 |
| AMA Property Portfolio Ltd | Real estate | 2025 |
| Ambitious Competitions Ltd | Arts & recreation | 2024 |
| Ambitious Lifestyle Group Ltd | Wholesale & retail | 2019 |
| Amity Web Solutions Limited | Information & communication | 2005 |
| Amja Services Limited | Administrative & support | 2003 |
| AMR Property Solutions Ltd | Construction | 2023 |
| AMT Management Consultants Limited | Wholesale & retail | 2018 |
| Anaptyx UK Ltd | Professional & scientific | 2022 |