| Assanga Limited | Health & social care | 2017 |
| Assemble Ltd | Construction | 2004 |
| Assembly CRE Limited | Real estate | 2023 |
| Assembly CRE Management Ltd | Real estate | 2024 |
| Assembly JPM Ltd | Professional & scientific | 2023 |
| Asset Mart Ltd | Wholesale & retail | 2025 |
| Asset Renova Ltd | Real estate | 2025 |
| Assetguard Legal Services Limited | Extraterritorial | 2024 |
| Assetrock Corringham Ltd | Real estate | 2020 |
| Assetrock Cuffley Ltd | Real estate | 2016 |
| Assetrock Debden House Limited | Real estate | 2026 |
| Assetrock Enfield Limited | Real estate | 2017 |
| Assetrock Grace House Ltd | Real estate | 2026 |
| Assetrock Putney Ltd | Real estate | 2022 |
| Assets 4 Investment Limited | Real estate | 2026 |
| Assets Pro Ltd | Real estate | 2024 |
| Assignment Report Writing Limited | Professional & scientific | 2026 |
| Associated Financial Services (UK) Limited | Real estate | 2005 |
| Association International Tamils CIC | Health & social care | 2023 |
| Assosiate Enterprises Limited | Wholesale & retail | 2025 |
| Assured Development Finance Limited | Construction | 2025 |
| AST Build Group Ltd | Construction | 2026 |
| AST Fleet UK Ltd | Administrative & support | 2019 |
| Asta Four Ltd | Real estate | 2022 |
| Asta Holiday Ltd | Real estate | 2022 |
| Asta One Ltd | Real estate | 2017 |
| Asta Property Management Ltd | Real estate | 2025 |
| Asta Three Ltd | Households | 2022 |
| Asta Two Ltd | Real estate | 2018 |
| Aster UK Technologies Ltd | Information & communication | 2024 |
| Asteroids Mining Ltd | Mining & quarrying | 2025 |
| Asthejeweller Ltd | Manufacturing | 2026 |
| Asti Interiors Ltd | Professional & scientific | 2023 |
| Aston & Studland Ltd | Real estate | 2024 |
| Aston Chesham Estate Ltd | Real estate | 2018 |
| Aston Design & Build Ltd | Construction | 2025 |
| Aston Lettings Limited | Households | 2013 |
| Aston Merch Ltd | Manufacturing | 2024 |
| Aston Sterling Limited | Administrative & support | 2025 |
| Astonall Limited | Construction | 2018 |
| Astonea Limited | Real estate | 2022 |
| Astonishing Productions Limited | Arts & recreation | 2018 |
| Astput Ltd | Wholesale & retail | 2019 |
| Astra Holdings Ltd | Real estate | 2025 |
| Astra Investments Ltd | Real estate | 2013 |
| Astra Property London Limited | Real estate | 2005 |
| Astra Sourcing Ltd | Wholesale & retail | 2026 |
| Astral Energy Homes Ltd | Construction | 2019 |
| Astranest Wellness Ltd | Wholesale & retail | 2025 |
| Astria Estates Limited | Real estate | 2021 |
| Astros-Gr Ltd | Construction | 2018 |
| Astroscene Ltd | Real estate | 2026 |
| Astrum College | Education | 2023 |
| Asts (South) Ltd | Wholesale & retail | 2016 |
| Asuka (Europe) Ltd | Households | 2022 |
| Asuka Euro Limited | Real estate | 2002 |
| ASUKA247 Ltd | Construction | 2018 |
| Asuni Limited | Hospitality | 2020 |
| Asuzu (UK) Limited | Mining & quarrying | 2008 |
| Asuzu Property Limited | Real estate | 2018 |
| ASV Colchester Hospital Limited | Wholesale & retail | 2022 |
| ASV Development Ltd | Construction | 2017 |
| Asvacare Ltd | Wholesale & retail | 2020 |
| Asvpro Limited | Real estate | 2023 |
| ASX Enterprises Ltd | Real estate | 2025 |
| ASY Vision Ltd | Health & social care | 2015 |
| Asya Medical Services Ltd | Health & social care | 2022 |
| ASZ Group &Co Ltd | Construction | 2026 |
| Aszicon Ltd | Wholesale & retail | 2021 |
| AT Carpentry Solutions Ltd | Manufacturing | 2026 |
| AT Food Group Limited | Hospitality | 2025 |
| AT Orazone LLP | | 2021 |
| AT UK Properties Limited | Real estate | 2003 |
| AT Van Services Ltd | Manufacturing | 2025 |
| AT Vision Ltd | Transport & logistics | 2017 |
| ATA & Sons Enterprises Ltd | Wholesale & retail | 2025 |
| ATA Aesthetic Training Academy Ltd | Other services | 2022 |
| ATA Furniture Limited | Manufacturing | 2019 |
| ATA GAS Ltd | Construction | 2025 |
| ATA Safety First UK Ltd. | Wholesale & retail | 2015 |
| Atacity Property Limited | Real estate | 2025 |
| Atax Accounting Ltd | Professional & scientific | 2021 |
| Atax Consultants Ltd | Professional & scientific | 2017 |
| Atax Solutions Ltd | Professional & scientific | 2014 |
| ATC Hospitality Limited | Hospitality | 2018 |
| ATC Interiors Ltd | Manufacturing | 2025 |
| Atco Money Exchange Ltd. | Financial services | 2005 |
| Atelier Abdul Ltd | Manufacturing | 2024 |
| Atelier Escape Ltd | Real estate | 2025 |
| Atelier Luxe Ltd | Wholesale & retail | 2025 |
| Atelier Saba Holdings Ltd | Financial services | 2026 |
| Aterrapaving & Landscapes Ltd | Construction | 2026 |
| ATH Network Solution Ltd | Information & communication | 2019 |
| Atharva Trading Ltd | Wholesale & retail | 2025 |
| Athena NKP Ltd | Information & communication | 2018 |
| Athgir Ltd | Wholesale & retail | 2023 |
| Athletic Intelligence Ltd | Arts & recreation | 2006 |
| Athletic Zone Limited | Wholesale & retail | 2022 |
| Athwal Film Productions Ltd | Information & communication | 2024 |
| Atif Perwiz Consulting Ltd | Professional & scientific | 2025 |