| Asjo Ltd | Real estate | 2020 |
| Askern Food Ltd | Hospitality | 2021 |
| Askern Grill Ltd | Hospitality | 2017 |
| Askern Ings Management Company Limited | Professional & scientific | 2004 |
| Askern Mini Market Ltd | Wholesale & retail | 2025 |
| Askern Plumbing Limited | Construction | 2022 |
| Askern Properties Ltd | Households | 2022 |
| Askern Recreation and Sports Club Limited | Hospitality | 2007 |
| Askern Road Garage Limited | Wholesale & retail | 2021 |
| Askern Stores Ltd | Wholesale & retail | 2019 |
| Askern Ward Community Partnership | Health & social care | 2002 |
| Aslan Accountancy Services Ltd | Professional & scientific | 2024 |
| Aslan Payroll Ltd | Professional & scientific | 2025 |
| Asli NAZ Limited | Real estate | 2023 |
| ASM Investments Ltd | Professional & scientific | 2019 |
| ASP Doncaster Limited | Professional & scientific | 2025 |
| Aspect Joinery Ltd | Construction | 2025 |
| Aspect Steel Services Limited | Professional & scientific | 2025 |
| Aspect Testing Ltd | Construction | 2013 |
| Aspen Fencing & Construction Ltd | Construction | 2025 |
| Aspen Financial Strategies Limited | Financial services | 1998 |
| Asphalt Maintenance Co. Limited | Professional & scientific | 2025 |
| Aspira Business Solutions, Ltd | Professional & scientific | 2023 |
| Aspira IT Limited | Information & communication | 2009 |
| Aspire Building Services Limited | Construction | 2025 |
| Aspire Edge Ltd | Wholesale & retail | 2025 |
| Aspire HR Services Ltd | Administrative & support | 2025 |
| Aspire Lending Solutions Limited | Financial services | 2021 |
| ASPIRE-360 Ltd | Professional & scientific | 2025 |
| ASPIRE2EVOLVE UK Ltd | Health & social care | 2026 |
| Aspiring 2 CIC | Information & communication | 2013 |
| Asprey Brothers (Bespoke) Limited | Construction | 2020 |
| Asprey Brothers Limited | Construction | 2006 |
| ASR Property Holdings Ltd | Real estate | 2020 |
| Assar Holding Group Ltd | Construction | 2020 |
| Asscher Design Limited | Wholesale & retail | 2017 |
| Assentian Limited | Information & communication | 2016 |
| Asset Manager Live Limited | Extraterritorial | 2011 |
| Asset Turnaround Limited | Extraterritorial | 2013 |
| Assetwave Consulting Ltd | Information & communication | 2024 |
| Assist IT Solutions Limited | Information & communication | 2007 |
| Assistance 24/7 Limited | Wholesale & retail | 2022 |
| Assistica Solutions Ltd | Administrative & support | 2025 |
| Associated Management Ltd | Construction | 2005 |
| Associated Signs and Graphic Design Ltd | Manufacturing | 2009 |
| Assurant Line Limited | Professional & scientific | 2023 |
| Assurebond Limited | Extraterritorial | 2009 |
| Aster and Bumble Limited | Wholesale & retail | 2025 |
| Aster Management Services Ltd | Professional & scientific | 2025 |
| Aston Homes (Yorkshire) Limited | Construction | 2017 |
| Astonishing Care Limited | Transport & logistics | 2021 |
| Astonishing Cleaning Limited | Administrative & support | 2018 |
| Astonishing Recruitment Limited | Administrative & support | 2023 |
| Astrabound Limited | Arts & recreation | 2007 |
| Astraquay Ltd | Education | 2026 |
| Astute Consultancy Group Limited | Professional & scientific | 2022 |
| Aswan Cuisine Limited | Hospitality | 2011 |
| Asylum Facilities Ltd | Construction | 2023 |
| AT Boiler Company Ltd | Construction | 2017 |
| AT DRY Lining Systems Ltd | Construction | 2017 |
| AT Homecare Holdings Limited | Financial services | 2022 |
| AT Randall Engineering Limited | Manufacturing | 2025 |
| ATA (Doncaster) Ltd | Professional & scientific | 2018 |
| Atco Enterprises (Doncaster) Ltd | Other services | 2020 |
| Atco Enterprises Ltd | Other services | 2020 |
| Atech Building&Electrical Solutions Ltd | Construction | 2025 |
| Ates Pizza Limited | Hospitality | 2025 |
| Atesh Doner Ltd | Wholesale & retail | 2021 |
| Atesogullari Ltd | Hospitality | 2025 |
| Athame Creative Limited | Professional & scientific | 2018 |
| Athena Education Services Ltd | Education | 2020 |
| Athena Grange Consulting Limited | Professional & scientific | 2025 |
| Athena MGT Limited | Professional & scientific | 2025 |
| Athens Catering Limited | Hospitality | 2023 |
| Athletic Boxing Club CIC | Arts & recreation | 2024 |
| Athlon Properties Ltd | Real estate | 2023 |
| ATJ Leeds Limited | Hospitality | 2024 |
| ATK Retail Ltd | Wholesale & retail | 2024 |
| Atkinson Consulting Services Limited | Health & social care | 2021 |
| Atlanta Compa International Ltd | Professional & scientific | 2018 |
| Atlantic Accountancy Ltd | Administrative & support | 2020 |
| Atlantic Estates North Limited | Real estate | 2002 |
| Atlantic Genetics LLP | | 2020 |
| Atlantic Scuba Ltd | Arts & recreation | 2024 |
| Atlantic View Services Ltd | Health & social care | 2025 |
| Atlantis Industrial Cooling Ltd | Manufacturing | 2023 |
| Atlas Electrical & Security Ltd | Construction | 2018 |
| Atlas Safety Ltd | Professional & scientific | 2025 |
| Atlas Steel Welding Ltd | Manufacturing | 2026 |
| ATM Express Ltd | Transport & logistics | 2021 |
| Atmos Renewables Ltd. | Construction | 2022 |
| Atomic Achievers Ltd | Education | 2024 |
| Atomic Brands Ltd | Wholesale & retail | 2025 |
| Atpc Holding Ltd | Financial services | 2020 |
| ATR Fire and Security Ltd | Administrative & support | 2022 |
| ATR Management Services Ltd | Professional & scientific | 2018 |
| ATS Group Limited | Transport & logistics | 2023 |
| ATS Renting Limited | Transport & logistics | 2008 |
| Atsmed Limited | Health & social care | 2025 |
| Atta Food Store Ltd | Wholesale & retail | 2026 |