| 'I MI' Community Advocacy Support Services CIC | Health & social care | 2026 |
| 03672648 Limited | Construction | 1998 |
| 1ST Choice Lettings Limited | Real estate | 2006 |
| 2 the Street Ltd | Hospitality | 2025 |
| 24INCHES Ltd | Wholesale & retail | 2023 |
| 3 BAI Ltd | Hospitality | 2023 |
| 360ABILITY Sport | Education | 2021 |
| 3Q Scientific Limited | Professional & scientific | 2014 |
| 3S Storage Ltd | Transport & logistics | 2021 |
| 3TM Transport Limited | Transport & logistics | 2023 |
| 7 Sisters Catering Ltd | Extraterritorial | 2007 |
| 7 Sisters Kebab & Pizza House Limited | Hospitality | 2024 |
| 7DN Ltd | Other services | 2025 |
| 80/20 Training and Lifestyle Limited | Other services | 2025 |
| A & a Auto Electrical Ltd | Wholesale & retail | 2022 |
| A & a Electrical & Sons Limited | Wholesale & retail | 2010 |
| A & R Electrical (Wales) Limited | Construction | 2008 |
| A & S Tyres Limited | Wholesale & retail | 2013 |
| A 101 Solutions (UK) Ltd | Administrative & support | 2013 |
| A and P Building Ltd | Construction | 2025 |
| A P Mobile Car Valeting Ltd | Other services | 2016 |
| A Pro Tree & Landscaping Ltd | Administrative & support | 2026 |
| A Star Forensics Ltd | Information & communication | 2011 |
| A to Z Cabs Limited | Transport & logistics | 2014 |
| A W Marine Trading Ltd | Agriculture & fishing | 2022 |
| A&A Propco Limited | Real estate | 2026 |
| A&H Private Limited | Wholesale & retail | 2024 |
| A&S Digital Ltd | Professional & scientific | 2023 |
| A-Z Mobile Ltd | Other services | 2017 |
| A. Weld (Holdings) Limited | Financial services | 2018 |
| A. Weld Limited | Manufacturing | 1991 |
| A.H. Williams Electrical Limited | Construction | 2010 |
| A.H.G. Corporate Group Ltd | Construction | 2018 |
| A.N.D. Employee Ownership Trustee Limited | Professional & scientific | 2026 |
| A.N.D. Textiles Limited | Wholesale & retail | 2011 |
| A1 Garden Solutions Wales Limited | Administrative & support | 2020 |
| A1 Industrial Roofing & Cladding Specialists Ltd | Construction | 2026 |
| A1 Leak Detection Ltd | Administrative & support | 2023 |
| AA Window and Door Services Limited | Construction | 2024 |
| AB Oral Care Services Ltd | Health & social care | 2023 |
| Abbey Stone Ltd | Manufacturing | 2023 |
| Abbey.Avl Limited | Professional & scientific | 2017 |
| ABC Re-Upholstery Limited | Manufacturing | 2026 |
| Aberdeen Investment Properties Limited | Real estate | 2026 |
| Above & Beyonds Roofing Trade Ltd | Construction | 2025 |
| Academy for Project Management Ltd | Professional & scientific | 2013 |
| ACADEMY4 International Ltd | Professional & scientific | 2022 |
| Accounting Office Software Ltd. | Information & communication | 2002 |
| Acjw Limited | Real estate | 2015 |
| ACP Quantity Surveying Ltd | Construction | 2015 |
| AD Sports Limited | Wholesale & retail | 2011 |
| AD Williams Consulting Ltd | Professional & scientific | 2024 |
| ADA Vending Ltd | Hospitality | 2025 |
| Adam Williams (Neath) Electrical Ltd | Construction | 2025 |
| Adams Repair Ltd | Wholesale & retail | 2024 |
| Adapt Fabrications Ltd | Professional & scientific | 2019 |
| Adapt Method Limited | Information & communication | 2023 |
| Adcredo Health Solutions Ltd | Manufacturing | 2025 |
| Adjs Holdings Ltd | Financial services | 2024 |
| Adrian Powell Developments Limited | Construction | 2006 |
| ADS Logistics (UK) Ltd | Transport & logistics | 2022 |
| Aesthetikkaa Ltd | Health & social care | 2021 |
| Afan Valley Maids Ltd. | Administrative & support | 2025 |
| Affilination Agency Ltd | Wholesale & retail | 2026 |
| Affordable Quality Windows Limited | Construction | 2020 |
| Afon Veterinary Centre Limited | Professional & scientific | 2017 |
| African Sauce Ltd | Wholesale & retail | 2026 |
| AGE Concern Neath Port Talbot | Administrative & support | 2001 |
| Aifloko Ltd | Wholesale & retail | 2026 |
| Aikya Homes Ltd | Real estate | 2020 |
| AJ & PP Properties Ltd | Real estate | 2023 |
| AJA Properties (Cardiff) Limited | Real estate | 2016 |
| AJD Rogers Ltd | Wholesale & retail | 2011 |
| Ajmb Homes Ltd | Real estate | 2025 |
| AJT Mechanical and Plumbing Engineers Ltd | Construction | 2023 |
| AJW Capital Investments Ltd | Transport & logistics | 2017 |
| AK Surrey Chauffeurs Ltd | Transport & logistics | 2025 |
| AKW Fabrications Ltd | Construction | 2021 |
| Alan Doyle Business Services Ltd | Information & communication | 2007 |
| Alan Hartshorn Ltd | Professional & scientific | 2020 |
| ALB Property Services Limited | Construction | 2019 |
| Alfa Beta Properties Ltd | Real estate | 2025 |
| Algotech Ltd | Financial services | 2018 |
| Aliha Ltd | Hospitality | 2024 |
| Alison George Sales & Lettings Limited | Real estate | 2026 |
| ALL in One Accountancy Limited | Professional & scientific | 2021 |
| ALL in One Accountancy Services Limited | Professional & scientific | 2016 |
| ALL in One Cleaning Services Ltd | Administrative & support | 2022 |
| Almic Limited | Professional & scientific | 2021 |
| ALN Consulting Wales Ltd | Professional & scientific | 2024 |
| Alpha Camera Crews Ltd | Information & communication | 2017 |
| AM Scaffolding (South Wales) Ltd | Construction | 2025 |
| AMC & Sons Ltd | Construction | 2016 |
| AMD Construction South Wales Ltd | Construction | 2024 |
| AMD Estates Southern Ltd | Real estate | 2026 |
| AMH Digital Limited | Information & communication | 2021 |
| AMJ Housing Ltd | Real estate | 2019 |
| Amman & District Motor Club Limited | Arts & recreation | 1998 |
| Ammu Foods Ltd | Hospitality | 2024 |
| AMT Design Consultants Ltd | Professional & scientific | 2018 |