| Amelia James Limited | Hospitality | 2019 |
| American Cars UK Limited | Wholesale & retail | 2019 |
| AMH Carpentry and Building Ltd | Other services | 2020 |
| Amore Luxe Limited | Other services | 2025 |
| Amour Cosmetics Ltd | Wholesale & retail | 2024 |
| Amss Fabrications Ltd | Professional & scientific | 2018 |
| AMV Services Holdings Limited | Financial services | 2020 |
| AMY Louise Properties Limited | Hospitality | 2023 |
| Amya Consultancy Ltd | Information & communication | 2026 |
| Amya Travel Ltd | Administrative & support | 2024 |
| An-Ex Analytical Services Limited | Professional & scientific | 1988 |
| An-Tec Logistic Limited | Manufacturing | 2023 |
| Anchor Inn (Bleadon) Ltd | Hospitality | 2005 |
| Anchor Success Ltd | Professional & scientific | 2011 |
| Anchorline Group Ltd | Administrative & support | 2026 |
| Ancon Construction Limited | Construction | 2016 |
| Anderson Brickwork and Construction Ltd | Construction | 2023 |
| Andrew Cooper Car Body Repairs Limited | Wholesale & retail | 2005 |
| Andrew Smith OIL and GAS Ltd | Professional & scientific | 2015 |
| Andrews & Matthews Plumbing & Heating Ltd | Construction | 2026 |
| Anesi Limited | Construction | 2025 |
| Angelocity Services Ltd | Transport & logistics | 2023 |
| Anglegovern Limited | Water & waste | 1996 |
| Anikin Aviation Limited | Manufacturing | 2019 |
| Animal Cardio Care Ltd | Professional & scientific | 2024 |
| ANN & Lee's Nails Ltd | Other services | 2026 |
| ANN Hugh Ltd | Wholesale & retail | 2009 |
| Anna Broughton Property Limited | Financial services | 2026 |
| Anola Consulting Ltd | Professional & scientific | 2023 |
| Anstee Landscape & Tree Felling Contractors Limited | Other services | 2002 |
| Antana Kamhat Limited | Real estate | 2021 |
| Antidemon Software Limited | Information & communication | 2021 |
| Antluc Properties Ltd | Construction | 2023 |
| Anwar Projects Ltd | Construction | 2017 |
| AP Design Solutions Ltd. | Arts & recreation | 2015 |
| AP HR Consulting Services Ltd | Administrative & support | 2024 |
| Apex Drilling (Holdings) Limited | Financial services | 2007 |
| Apex Drilling Services Limited | Construction | 1993 |
| Apex Properties (Bridgend) Limited | Real estate | 2026 |
| Apex Revolution Ltd | Transport & logistics | 2019 |
| Apex Testing Solutions Limited | Professional & scientific | 2012 |
| Apiary Publishing Ltd | Other services | 2017 |
| Apms Builders Limited | Construction | 2015 |
| Apna Bazaar Bridgend Ltd | Wholesale & retail | 2021 |
| Apollo Business Village Ltd | Real estate | 2016 |
| Apollo Teaching Services Employee Ownership Trustee Ltd | Professional & scientific | 2023 |
| Apollo Teaching Services Ltd | Education | 2006 |
| Apparel&Co Ltd | Wholesale & retail | 2023 |
| Appeal Ltd | Information & communication | 2024 |
| Apple and Blackcurrant Limited | Information & communication | 2024 |
| Appledene Caterers Limited | Hospitality | 1973 |
| APR Access Ltd | Administrative & support | 2021 |
| APR Distributors Limited | Manufacturing | 2003 |
| April Complete Care Solutions Ltd | Health & social care | 1999 |
| Apsee Group Limited | Financial services | 2026 |
| Apsee Holdings Ltd | Real estate | 2021 |
| Apsee Limited | Transport & logistics | 2025 |
| Apsee Properties Limited | Real estate | 2026 |
| APW Coachworks Limited | Manufacturing | 1993 |
| Aqua Escape Ltd | Wholesale & retail | 2025 |
| Aquasafe Building Services Engineers Limited | Professional & scientific | 2007 |
| Aquavita Leisure Limited | Wholesale & retail | 2015 |
| ARA Medtech Consultancy Ltd | Professional & scientific | 2021 |
| ARB Autocare Limited | Wholesale & retail | 2008 |
| Arbcymru Ltd | Agriculture & fishing | 2015 |
| Arborzen Ltd | Agriculture & fishing | 2024 |
| Arc-Tech Support Ltd. | Professional & scientific | 2008 |
| Arcane Forge Software Limited | Information & communication | 2024 |
| Archdere Limited | Extraterritorial | 2025 |
| Archer Roofing and Building Services Ltd | Construction | 2017 |
| Architectural Design (Ad-Sw) Ltd | Professional & scientific | 2020 |
| Archreed Limited | Extraterritorial | 2025 |
| Arcs Group Limited | Financial services | 2021 |
| Arcstead Limited | Construction | 2025 |
| Area Roofing Services Ltd | Construction | 2022 |
| Aries Hair & Beauty Limited | Other services | 2023 |
| Ariian Limited | Professional & scientific | 2018 |
| ARK Campers Limited | Wholesale & retail | 2021 |
| ARK Effect Ltd | Professional & scientific | 2021 |
| ARK Paving Ltd | Administrative & support | 2017 |
| Arloesi Engineering Ltd | Professional & scientific | 2023 |
| Armada Real Estate Ltd | Extraterritorial | 2015 |
| Armex Tech Ltd | Administrative & support | 2014 |
| Armoury Court Ebbw Vale Limited | Households | 1998 |
| Aroc Developments Limited | Construction | 2014 |
| Arrow Mortgages Ltd | Financial services | 2023 |
| Arsalan Private Limited | Wholesale & retail | 2024 |
| Art of Ethos Ltd | Arts & recreation | 2025 |
| Artemis Events Limited | Arts & recreation | 2024 |
| Arthouse Design Ltd | Professional & scientific | 2026 |
| Arthurleah Limited | Professional & scientific | 2014 |
| Arundel House Estates Limited | Construction | 1987 |
| Asbri Planning Limited | Construction | 2007 |
| ASH Property Developments (Bridgend) Ltd | Real estate | 2025 |
| Ashbolt Property Holdings Ltd | Real estate | 2024 |
| Ashcade Limited | Construction | 2022 |
| Ashes to Life Ltd | Manufacturing | 2022 |
| Ashoka (Bridgend) Limited | Hospitality | 2013 |
| Ashrate Limited | Extraterritorial | 2026 |
| Ashwynn Limited | Wholesale & retail | 2025 |