| 1 Fine Day Ltd | Households | 2011 |
| 1 IS 2 Many Limited | Administrative & support | 2014 |
| 10-TEN Construction and Engineering Ltd | Construction | 2019 |
| 1770 Developments Limited | Construction | 2015 |
| 1940S Swansea Limited | Arts & recreation | 2001 |
| 1ST Line Group Ltd | Financial services | 2026 |
| 1ST Line Legal Services Ltd | Professional & scientific | 2020 |
| 2X2 Construction Ltd | Construction | 2022 |
| 30WEST Consultancy Limited | Professional & scientific | 2020 |
| 3D Levelling Solutions Limited | Agriculture & fishing | 2019 |
| 3D Site Solutions Ltd | Construction | 2023 |
| 5 Star Super Hand Car Wash Ltd | Administrative & support | 2025 |
| A & D Davies Engineering Ltd | Manufacturing | 2024 |
| A J'S Property Maintenance (Llanelli) Limited | Construction | 2018 |
| A Taste of the County (Four Seasons) Limited | Wholesale & retail | 2007 |
| A. Duffin Haulage Limited | Mining & quarrying | 2004 |
| A.I.P.I. Limited | Real estate | 2003 |
| A.V. Roofing & Cladding Limited | Construction | 2024 |
| A7 TCT Limited | Administrative & support | 2025 |
| Abaca Ltd | Manufacturing | 2001 |
| ABC Fabrications Limited | Manufacturing | 2022 |
| Abernant Rental Units Limited | Real estate | 2010 |
| Absolute Assistance Limited | Health & social care | 2023 |
| Absolute Marquees Limited | Administrative & support | 2009 |
| Ace Renovations Ltd | Construction | 2017 |
| ACS Wales Limited | Construction | 2000 |
| Addons IQ Limited | Information & communication | 2026 |
| Addysg Engagement Ltd | Education | 2025 |
| Adejohn Medical Services Ltd | Health & social care | 2025 |
| Adeni Limited | Professional & scientific | 2002 |
| Adept GRP Ltd | Manufacturing | 2004 |
| Adira Limited | Information & communication | 2004 |
| AG52 Limited | Real estate | 2020 |
| Agade Construction Limited | Other services | 2014 |
| Ailey’S Property Development Limited | Real estate | 2020 |
| Al's Big Bikeshed Ltd | Wholesale & retail | 2024 |
| Albert Williams Ltd | Construction | 2018 |
| Alexandra's Aesthetics Limited | Other services | 2019 |
| ALF Developments Limited | Real estate | 2012 |
| ALL Born Curious Childcare Ltd | Health & social care | 2022 |
| ALL Born Curious Limited | Health & social care | 2020 |
| Alpha Librae Ltd | Wholesale & retail | 2017 |
| Alphawave Technologies Limited | Information & communication | 2025 |
| Alston Trading Ltd | Wholesale & retail | 2012 |
| Altron Communications Equipment Limited | Manufacturing | 1971 |
| Altron Manufacturing and Engineering Limited | Manufacturing | 2001 |
| Alun M Thomas CYF | Real estate | 2024 |
| Aman Eco-Tech Limited | Professional & scientific | 2001 |
| Amanah’S Fine Dining Ltd | Hospitality | 2025 |
| Amcat Service Ltd | Construction | 2022 |
| Amera-Leia Ltd | Other services | 2019 |
| Amman Care Services Limited | Health & social care | 2002 |
| Amman Concrete Products Limited | Construction | 1993 |
| Amman Construction Ltd | Construction | 2012 |
| Amman Cottage Company (ACC) Ltd | Information & communication | 2023 |
| Amman Heating Services Ltd | Construction | 2018 |
| Amman Stores Ltd | Wholesale & retail | 2025 |
| Amman Tyre Shop Ltd | Wholesale & retail | 2019 |
| Amman Valley Group Limited | Financial services | 2011 |
| Amman Valley Railway Society | Transport & logistics | 2006 |
| Amman Valley RAW Ltd | Manufacturing | 2023 |
| Amman Valley Storage Limited | Administrative & support | 2025 |
| Amman Valley Trotting Club Limited | Arts & recreation | 2004 |
| Amman Valley Welders Limited | Extraterritorial | 2011 |
| Ammanford AFC Ltd | Arts & recreation | 2020 |
| Ammanford Catering Limited | Hospitality | 2023 |
| Ammanford Evangelical Church | Other services | 2001 |
| Ammanford Holding Limited | Financial services | 2025 |
| Ammanford Ltd | Wholesale & retail | 2011 |
| Ammanford MOT Station Ltd | Wholesale & retail | 2014 |
| Ammanford Property Limited | Real estate | 2025 |
| Ammanford Ranna Ghor Limited | Hospitality | 2019 |
| Ammanford Recycling Limited | Wholesale & retail | 2016 |
| Ammanford RFC Limited | Arts & recreation | 2015 |
| Ammanford Tyre & Auto Ltd | Wholesale & retail | 2014 |
| Ammanvalleyphysiotherapy Ltd | Other services | 2012 |
| Ampm Nutrition Ltd | Manufacturing | 2024 |
| Analogue Software Limited | Information & communication | 2022 |
| Andreea Transport Ltd | Transport & logistics | 2018 |
| Andrew Jones (the Vatman) Limited | Professional & scientific | 2012 |
| Andrew's Chilled Foods Limited | Wholesale & retail | 2003 |
| Anna Ashton Estate Agents Ltd | Real estate | 2017 |
| Anoeth Limited | Information & communication | 2004 |
| Apexhomeimprovementstd Ltd | Wholesale & retail | 2017 |
| APL Pipework Services Ltd | Construction | 2015 |
| AR Water Services Limited | Water & waste | 2023 |
| ARK Consultancy & Property Management Ltd | Professional & scientific | 2025 |
| Armis Developments Ltd | Construction | 2022 |
| Arspg Holdings Limited | Financial services | 2018 |
| Art of Eco Limited | Manufacturing | 2013 |
| ASE Consulting Limited | Professional & scientific | 2026 |
| Ashfit Limited | Arts & recreation | 2016 |
| Austin Richards Homes Ltd | Construction | 2017 |
| Autograffeg Limited | Information & communication | 2001 |
| AV Coatings Limited | Manufacturing | 2009 |
| AV Film and Design Limited | Manufacturing | 2016 |
| Avad Construction & Maintenance Ltd | Construction | 2024 |
| Avad Investments Limited | Financial services | 2018 |
| Avad Management Limited | Administrative & support | 2019 |
| AVI8 Consulting Ltd | Education | 2026 |