| A4B (Cardiff) Ltd | Other services | 2018 |
| A4DABLE Motors Ltd | Wholesale & retail | 2017 |
| A4K-SPORTS Apparel Ltd | Wholesale & retail | 2024 |
| A5 Cars Limited | Other services | 2011 |
| A5 Holdings Limited | Real estate | 2024 |
| AA & D Trading Ltd | Hospitality | 2024 |
| AA Ahmed Technology Ltd | Information & communication | 2024 |
| AA Assets Cardiff Ltd | Real estate | 2022 |
| AA Cars Cardiff Ltd | Wholesale & retail | 2023 |
| AA Chiropractic Ltd | Professional & scientific | 2023 |
| AA Construct Services Ltd | Construction | 2025 |
| AA Construction Solution Ltd | Construction | 2017 |
| AA Electricals (SY) Ltd | Wholesale & retail | 2019 |
| AA Global Consultants Limited | Professional & scientific | 2012 |
| AA Holiday Properties Ltd | Hospitality | 2020 |
| AA Homes & Developments Limited | Real estate | 2016 |
| AA Overture Limited | Real estate | 2022 |
| AA Printers Limited | Administrative & support | 2015 |
| AA Props Ltd | Real estate | 2019 |
| AA Trading (UK) Limited | Real estate | 2006 |
| AA Vera Plaza Corporation Limited | Wholesale & retail | 2024 |
| Aa&N Ltd | Construction | 2025 |
| AA86 Foods Ltd | Hospitality | 2026 |
| AAA Al-Pangea Saudi Visas Limited | Other services | 2018 |
| AAA Foods Cardiff Ltd | Wholesale & retail | 2023 |
| AAA Green Clean Ltd | Administrative & support | 2025 |
| AAA IT Consulting Limited | Information & communication | 2017 |
| AAA Italian Ltd | Hospitality | 2023 |
| AAA Landscape Gardeners Ltd | Administrative & support | 2024 |
| AAA Services Limited | Other services | 2025 |
| AAA Tyres Ltd | Manufacturing | 2019 |
| AAA Web Limited | Manufacturing | 2013 |
| Aaa-Allpro Groundswork & Landscapes Ltd | Administrative & support | 2019 |
| Aaab Ltd | Wholesale & retail | 2018 |
| Aaanasir Ltd | Information & communication | 2019 |
| AAC Carpentry & Construction Limited | Manufacturing | 2022 |
| AAC Direct Limited | Other services | 2023 |
| Aacrown Ltd | Wholesale & retail | 2019 |
| Aadam Imani Malaika Investments Ltd | Real estate | 2024 |
| Aadil Pharm Ltd | Administrative & support | 2018 |
| Aadzup.Com Ltd | Information & communication | 2016 |
| AAG Family Investment Holdings Ltd | Health & social care | 2026 |
| Aahil Foods Limited | Hospitality | 2023 |
| Aailayah Smartbuy Ltd | Wholesale & retail | 2024 |
| AAJ International Ltd | Wholesale & retail | 2021 |
| AAK Ventures Ltd | Hospitality | 2020 |
| Aamby Valley (UK) Limited | Other services | 2012 |
| Aant Ltd | Transport & logistics | 2025 |
| Aapoloprime Cleaning Limited | Administrative & support | 2026 |
| AAR Bradford Ltd | Hospitality | 2016 |
| AAR Group Ltd | Professional & scientific | 2016 |
| AAR Management Ltd | Professional & scientific | 2016 |
| AAR Property Ltd | Real estate | 2016 |
| Aara Foods Limited | Wholesale & retail | 2019 |
| Aarc (Management & Consultancy) Ltd | Construction | 2025 |
| Aark Racing Limited | Arts & recreation | 2018 |
| Aarna Hospitality Ltd | Hospitality | 2025 |
| Aaron Abbey Care Services Limited | Health & social care | 2013 |
| Aaron Feeney Ltd | Information & communication | 2016 |
| Aaron Freeman Ltd | Other services | 2018 |
| Aaron Morton Ltd | Other services | 2015 |
| Aaron Trade World Ltd | Construction | 2017 |
| Aaron Wise Limited | Real estate | 2015 |
| AAS Traders Ltd | Wholesale & retail | 2022 |
| Aasobe Limited | Real estate | 2014 |
| Aasra Foods Ltd | Hospitality | 2020 |
| Aasrm Ltd | Other services | 2024 |
| Aatrek Limited | Construction | 2007 |
| Aatrek Properties Limited | Real estate | 2023 |
| Aaua Limited | Transport & logistics | 2025 |
| Aaura Care Group Ltd | Health & social care | 2026 |
| Aayan Outlet Ltd | Wholesale & retail | 2025 |
| AB Asset & Property Investments Ltd | Real estate | 2023 |
| AB Building Ltd | Construction | 2015 |
| AB Davies Ltd | Construction | 2026 |
| AB Digital and Media Ltd | Wholesale & retail | 2018 |
| AB Event Technology Limited | Information & communication | 2019 |
| AB FAB Organised Events Limited | Other services | 2019 |
| AB Finance Consulting Ltd | Professional & scientific | 2022 |
| AB Heights Carpentry Ltd | Construction | 2021 |
| AB Prestige Limited | Wholesale & retail | 2026 |
| AB Professionals Ltd | Professional & scientific | 2018 |
| AB Rail Contracting Ltd | Construction | 2020 |
| AB Sans EMD Ltd | Information & communication | 2025 |
| Ab&Ib Groups Ltd | Wholesale & retail | 2025 |
| Ab&K Services Limited | Other services | 2018 |
| Ab&Mb Limited | Information & communication | 2019 |
| ABA Building (South) Ltd | Construction | 2019 |
| ABA Building Services Ltd | Construction | 2026 |
| ABA Swansea Limited | Construction | 2016 |
| Abacus 88 Limited | Information & communication | 2016 |
| Abacus Accounting & Taxation Consultants Ltd | Professional & scientific | 2014 |
| Abacus House Management (Cardiff) Ltd | Households | 2018 |
| Abacus Marketing Solutions Ltd | Professional & scientific | 2015 |
| Abacusoft Ltd | Wholesale & retail | 2022 |
| Abae Ltd | Other services | 2024 |
| Abaset Collections Ltd | Information & communication | 2020 |
| ABB Controls Ltd | Professional & scientific | 2025 |
| Abbas Property Management Limited | Real estate | 2025 |
| Abbas Sons Ltd | Wholesale & retail | 2026 |