| ASQ Design Ltd | Professional & scientific | 2020 |
| Asquith Park Management Company Limited | Households | 2015 |
| ASR Security Consultancy Ltd | Administrative & support | 2023 |
| Asrp Ltd | Real estate | 2024 |
| Assane Courier Ltd | Transport & logistics | 2020 |
| Asseco Health Ltd | Health & social care | 2019 |
| Asseco Properties Ltd | Real estate | 2018 |
| Assegai Trading Limited | Wholesale & retail | 2022 |
| Assemblify Limited | Professional & scientific | 2023 |
| Assemblive Ltd | Construction | 2019 |
| Assembly Bar Group Ltd | Hospitality | 2018 |
| Assembly House CIC | Arts & recreation | 2014 |
| Assembly Line Productions Limited | Arts & recreation | 2019 |
| Assenso Estates Limited | Real estate | 2024 |
| Asset Base Ltd | Professional & scientific | 2022 |
| Asset Construction Solutions Ltd | Construction | 2022 |
| Asset Finance UK Cashflow Limited | Financial services | 2011 |
| Asset Finance UK Holdings Limited | Financial services | 2013 |
| Asset Finance UK Limited | Wholesale & retail | 2004 |
| Asset Health Solutions Limited | Public administration | 2013 |
| Asset Management Consulting Limited | Professional & scientific | 1997 |
| Assiduos Limited | Wholesale & retail | 2024 |
| Assist Domiciliary Care Limited | Health & social care | 2012 |
| Assist Marketing Ltd | Professional & scientific | 2025 |
| Assisted Housing Group Ltd | Real estate | 2020 |
| Associate Design Time Holdings Limited | Financial services | 2025 |
| Associate Design Time Limited | Professional & scientific | 1989 |
| Associate Vintage Ltd | Wholesale & retail | 2026 |
| Associated Clean Technologies Ltd | Professional & scientific | 2022 |
| Associated Tower Cinemas Limited | Professional & scientific | 1982 |
| Associated Waste Management Limited | Water & waste | 2000 |
| Association of Marketing Facilitators CIC | Education | 2024 |
| Association of Northern Mediators | Other services | 2012 |
| Association of the Petroleum Industry of Kurdistan | Extraterritorial | 2023 |
| Assure Healthcare Group (South) Ltd | Health & social care | 2015 |
| Assured Bidco Limited | Financial services | 2024 |
| Assured Building Contractors Limited | Construction | 2003 |
| Assured Cars Limited | Wholesale & retail | 2025 |
| Assured Compliance Solutions (UK) Ltd | Professional & scientific | 2009 |
| Assured Data Protection Bidco Limited | Professional & scientific | 2023 |
| Assured Data Protection Limited | Information & communication | 2016 |
| Assured Data Protection Midco Limited | Professional & scientific | 2023 |
| Assured Data Protection Topco Limited | Professional & scientific | 2023 |
| Assured Management Limited | Professional & scientific | 2007 |
| Assured Midco 1 Limited | Financial services | 2024 |
| Assured Midco 2 Limited | Financial services | 2024 |
| Assured Money (UK) Limited | Real estate | 2011 |
| Assured Topco Limited | Financial services | 2024 |
| Assurereporting Limited | Health & social care | 2016 |
| AST Accountants Ltd | Professional & scientific | 2025 |
| Astelle Ltd | Wholesale & retail | 2024 |
| Aster Financial Consulting Ltd | Other services | 2021 |
| Asto Ventures Ltd | Information & communication | 2026 |
| Aston Commercial Finance Limited | Financial services | 2023 |
| Aston Homes (Leeds) Limited | Real estate | 2019 |
| Aston Park Properties Limited | Real estate | 2021 |
| Aston Properties (Leeds) Limited | Real estate | 2003 |
| Aston Service London Limited | Wholesale & retail | 2008 |
| Aston Student Properties Limited | Real estate | 2021 |
| Aston-Young Holdings Ltd | Real estate | 2024 |
| Astonline Limited | Other services | 2025 |
| Astoria Ballroom (Leeds) Limited | Professional & scientific | 1946 |
| Astoria Leisure Company Limited | Real estate | 1997 |
| Astorya Holdings Limited | Information & communication | 2023 |
| Astound Web NET Limited | Information & communication | 2012 |
| Astra Assets Ltd | Administrative & support | 2017 |
| Astra Automotive Ltd | Wholesale & retail | 2020 |
| Astra Bridge Ltd | Real estate | 2025 |
| Astra North Retail Ltd | Wholesale & retail | 2026 |
| Astradyne Limited | Information & communication | 2006 |
| Astraea Accountants Ltd | Professional & scientific | 2020 |
| Astro Office Limited | Wholesale & retail | 2025 |
| Asturias Solutions Ltd | Administrative & support | 2020 |
| Astute Insurance Solutions Limited | Financial services | 2008 |
| Astute Investments Ltd | Real estate | 2016 |
| Astute Property Partners Limited | Real estate | 2019 |
| Asup Limited | Information & communication | 2010 |
| ASV Aroma Limited | Wholesale & retail | 2024 |
| ASW Partnership LLP | | 2014 |
| Aszo Vintage Ltd | Wholesale & retail | 2026 |
| AT Construction Contracts Ltd | Construction | 2025 |
| AT Developments (Yorkshire) Limted | Construction | 2006 |
| AT Leeds Limited | Health & social care | 2026 |
| AT Merchants Ltd | Real estate | 2025 |
| AT Plumbing Services Ltd | Construction | 2015 |
| AT Roofers Ltd | Construction | 2026 |
| AT Thresholds Ltd | Professional & scientific | 2026 |
| AT Transport Services Yorkshire Ltd | Transport & logistics | 2012 |
| AT Vault Limited | Wholesale & retail | 2025 |
| At&T Consulting Ltd | Professional & scientific | 2018 |
| At-At Power Limited | Wholesale & retail | 2010 |
| ATA Records Ltd | Arts & recreation | 2017 |
| Atabis Group Limited | Health & social care | 2025 |
| Atac Properties Ltd | Real estate | 2019 |
| Atalante Marketing Limited | Professional & scientific | 2020 |
| Atasa Ltd | Professional & scientific | 2013 |
| ATB Architectural Ltd | Professional & scientific | 2021 |
| ATB FAE Ltd | Information & communication | 2023 |
| ATC (Chapel Allerton) LLP | | 2006 |
| ATC Developments (Leeds) Limited | Real estate | 2006 |