| 'LL Motors Ltd | Wholesale & retail | 2017 |
| 1A Medispa Limited | Other services | 2018 |
| 1ST Supplies Industrial Ltd | Manufacturing | 2015 |
| 2 Core Contracts Ltd | Construction | 2020 |
| 2D Construction 2018 CYF | Construction | 2018 |
| 4TH Street Traffic Ltd | Arts & recreation | 2012 |
| 50 Plus Later Life Planning Limited | Financial services | 2015 |
| 9624 Limited | Information & communication | 2016 |
| A & J Suppliers Ltd | Other services | 2016 |
| A J Events Services Ltd | Arts & recreation | 2019 |
| A Lane & Associates Limited | Construction | 2005 |
| A Lane Developments Limited | Construction | 2018 |
| A Little Help With SJ Ltd | Administrative & support | 2024 |
| A'Hearne Cladding Ltd | Construction | 2025 |
| A. J. Asset Holdings Limited | Professional & scientific | 2012 |
| A.B.S Property Portfolio Limited | Real estate | 2017 |
| A.Gold Construction Ltd | Construction | 2021 |
| A.J. Stevens & Sons Limited | Wholesale & retail | 2003 |
| A.S.M Networks Ltd | Information & communication | 2018 |
| A.T. Motors Ltd | Wholesale & retail | 2010 |
| AAC98 Limited | Health & social care | 2007 |
| AB FAB (Blackwood) Limited | Other services | 2014 |
| AB Fit Training LP | | 2019 |
| Access Design Solutions UK Ltd | Professional & scientific | 2012 |
| Accolade Land Services | | 1996 |
| Actionzone Holdings Limited | Financial services | 2024 |
| Adam's Estate (Blackwood) Ltd | Real estate | 2023 |
| Adams Construction Services (Wales) Ltd | Construction | 2025 |
| Advanced Mototec Ltd | Wholesale & retail | 2005 |
| Aegon Surveying Ltd | Construction | 2018 |
| Aelwyd Refurbishments Limited | Construction | 2026 |
| Aeroquest Flight Training Limited | Education | 2024 |
| AG James & SON (Plant Hire) Limited | Construction | 2008 |
| AG Logistics Ltd | Transport & logistics | 2013 |
| AHJ Sales Ltd | Wholesale & retail | 2018 |
| Airvolk Motors Limited | Wholesale & retail | 2003 |
| AJ Stores Ltd | Wholesale & retail | 2021 |
| AJK Carpentry Services Limited | Construction | 2026 |
| AJT Accountancy (SW) Ltd | Professional & scientific | 2025 |
| Alao Properties Ltd | Real estate | 2025 |
| Alex Smith Properties Ltd | Real estate | 2025 |
| Align Chiropractic Ltd | Health & social care | 2024 |
| ALIGNMENT4 Limited | Administrative & support | 2014 |
| Allershaw Limited | Professional & scientific | 2008 |
| Allure Aesthetics Ltd | Health & social care | 2016 |
| Alro Homes Ltd | Financial services | 2021 |
| ALT Essentials Limited | Wholesale & retail | 2025 |
| Altsounds Limited | Information & communication | 2005 |
| AM Unique Group Ltd | Financial services | 2025 |
| Amarna Horizon Limited | Professional & scientific | 2021 |
| Amber Fleet Management Limited | Wholesale & retail | 2003 |
| Amici Italian Ltd | Hospitality | 2024 |
| Amici Takeaway Ltd | Hospitality | 2025 |
| Ampersand-It Ltd | Information & communication | 2020 |
| AMS Heating & Plumbing Limited | Construction | 2010 |
| AMS Holdings Group Limited | Financial services | 2025 |
| Andicom Solutions Limited | Information & communication | 2017 |
| Andrew Roberts Accounting Services Limited | Professional & scientific | 2016 |
| ANR Blend Limited | Manufacturing | 2025 |
| ANR Group Limited | Financial services | 2025 |
| ANR Probake Limited | Extraterritorial | 2013 |
| ANR Probrand Limited | Manufacturing | 2025 |
| ANR Snacks Limited | Manufacturing | 2025 |
| Anthony Poole Ltd | Real estate | 2026 |
| AP & KP Properties Ltd | Real estate | 2026 |
| Aphrodite Beauty Therapy Clinic Ltd | Other services | 2019 |
| Apollo Procurement Ltd | Professional & scientific | 2020 |
| Applied Nutritional Research Ltd | Manufacturing | 2008 |
| Approvals Consultancy Services Limited | Professional & scientific | 2019 |
| APR Property Management Ltd | Extraterritorial | 2023 |
| Aramec Limited | Manufacturing | 2007 |
| Ardent Engineering Services Limited | Construction | 2015 |
| Ardor Domestics Ltd | Wholesale & retail | 2025 |
| Arfon Ironworks Limited | Manufacturing | 2011 |
| Argoed Automotive Centre Ltd | Wholesale & retail | 2019 |
| Argoed Autos Ltd | Wholesale & retail | 2021 |
| Argoed Wealth Management Ltd | Financial services | 2016 |
| Arrc Ltd | Professional & scientific | 2020 |
| Art Nation Ltd | Professional & scientific | 2025 |
| Art Travel Limited | Transport & logistics | 2015 |
| Arya Emery Property Ltd | Real estate | 2023 |
| AS Fire Services Ltd | Public administration | 2020 |
| Ashlar Technologies Ltd | Information & communication | 2026 |
| ASI Konnect Limited | Professional & scientific | 2025 |
| AT Stacey's Ltd | Other services | 2025 |
| Atlantic Service Company (U.K.) Limited | Manufacturing | 1974 |
| ATS Rendering Supplies Ltd | Wholesale & retail | 2026 |
| Audio Visual Alarms Fire and Security Limited | Administrative & support | 2018 |
| Aurum Mindset Ltd | Extraterritorial | 2024 |
| Auto Assets Ltd | Wholesale & retail | 2023 |
| Auto House Properties Limited | Real estate | 2023 |
| AVA Business Energy Solutions Ltd | Administrative & support | 2026 |
| Avendor Limited | Real estate | 2011 |
| Avista Window Systems Limited | Construction | 2017 |
| Awaydayz Ltd | Wholesale & retail | 2022 |
| Aweber Design Limited | Information & communication | 2012 |
| B Osmond Consulting Ltd | Professional & scientific | 2023 |
| B.E.S.T. Electrical Limited | Construction | 2003 |
| B.L& V.D Ltd | Construction | 2024 |
| Babe Cave Enterprise Ltd | Arts & recreation | 2023 |