| AS Diamond House Ltd | Construction | 2018 |
| AS Fagan Engineering Ltd | Wholesale & retail | 2014 |
| AS Super Limited | Wholesale & retail | 2016 |
| AS Technic Ltd | Manufacturing | 2020 |
| AS TEQ Ltd | Wholesale & retail | 2024 |
| ASA First Limited | Administrative & support | 2013 |
| ASA Innovative Healthcare Limited | Health & social care | 2024 |
| Asad Services Ltd | Wholesale & retail | 2024 |
| Asaftei Construction Ltd | Construction | 2020 |
| Asai Capital Ltd | Financial services | 2024 |
| Asante Bakes Limited | Extraterritorial | 2023 |
| Asavetei Limited | Construction | 2009 |
| ASB Property Lettings Ltd | Real estate | 2017 |
| ASC Contracting Ltd | Construction | 2020 |
| Aselkom Limited | Professional & scientific | 2023 |
| Asfer Limited | Hospitality | 2024 |
| Asgip Ltd | Real estate | 2018 |
| ASH Building Services Ltd | Construction | 2026 |
| ASH Developers Limited | Construction | 2016 |
| ASH Retailers and Wholesalers Ltd | Wholesale & retail | 2024 |
| Ashby Investments Ltd | Construction | 2021 |
| Ashcourt Limited | Professional & scientific | 1994 |
| Ashdal Properties Limited | Real estate | 2022 |
| Asher B Ltd | Construction | 2025 |
| Ashiana Trust Limited | Health & social care | 2008 |
| Ashini Engineering Limited | Professional & scientific | 2021 |
| Ashley Beauty Limited | Other services | 2026 |
| Ashley King Limited | Professional & scientific | 2003 |
| Ashley Martin & Company Limited | Real estate | 1993 |
| Ashmore Corporation Ltd | Education | 2021 |
| Ashmount Estates Limited | Real estate | 2016 |
| Ashq Fish Market Limited | Wholesale & retail | 2022 |
| Ashray Holdings Limited | Health & social care | 2023 |
| Ashsam Properties Limited | Construction | 2006 |
| Ashton Court Hotel Ltd | Hospitality | 2022 |
| Ashtree Close (Surbiton) Residents' Association Limited | Households | 1979 |
| Ashtree Court (ST. Albans) Management Company Limited | Households | 1990 |
| Ashval Holdings Ltd | Real estate | 2022 |
| ASI (Heritage Park) Ltd | Real estate | 2020 |
| Asia Cleaning Limited | Administrative & support | 2021 |
| Asian Eats Ltd | Hospitality | 2021 |
| Asian-European Airways Limited | Transport & logistics | 2006 |
| Asili London Ltd | Wholesale & retail | 2024 |
| ASK Accountants & Business Advisors Ltd | Professional & scientific | 2015 |
| ASK for Services Limited | Construction | 2026 |
| ASK Linguistics Ltd | Professional & scientific | 2024 |
| ASK Salon Ltd | Other services | 2022 |
| Askeyuk Co. Limited | Manufacturing | 2020 |
| Askland Transfers Ltd | Transport & logistics | 2026 |
| ASM Property Group Ltd | Real estate | 2022 |
| Asma Associates Ltd | Financial services | 2016 |
| Aspen Collection Ltd | Wholesale & retail | 2016 |
| Aspenheath Limited | Real estate | 1983 |
| Aspire Business Consulting Limited | Professional & scientific | 2023 |
| Aspire Investment Properties Limited | Real estate | 2020 |
| Aspire TEK Ltd | Professional & scientific | 2013 |
| Aspire Trade Worldwide Limited | Financial services | 2011 |
| Asprey Building Services Ltd | Administrative & support | 2023 |
| Asprey Lettings Service Limited | Real estate | 2024 |
| Asprey Management Services Limited | Real estate | 2024 |
| Asprey Sales Services Limited | Real estate | 2024 |
| Asra Accounting Limited | Professional & scientific | 2026 |
| Asra Investment Limited | Real estate | 2013 |
| Assadi Grocery UK Ltd | Wholesale & retail | 2025 |
| Assetree Group 2 Ltd | Financial services | 2020 |
| Assetree Ltd | Professional & scientific | 2014 |
| Assetree Management Ltd | Professional & scientific | 2019 |
| Assets Logistics Ltd | Transport & logistics | 2014 |
| Assist HS Ltd | Professional & scientific | 2025 |
| Associated Property (UK) Limited | Real estate | 2013 |
| Association of Concerned Nigerians UK Ltd | Other services | 2019 |
| Assured Property Management Ltd | Administrative & support | 2017 |
| Astechs Limited | Information & communication | 2001 |
| Asteria Group Holdings Limited | Financial services | 2023 |
| Astonmere Limited | Professional & scientific | 2018 |
| Astra Pharma (UK) Limited | Wholesale & retail | 2001 |
| Astra Tours Ltd | Administrative & support | 2026 |
| Astrol Ltd | Construction | 2021 |
| Astryde Technologies Limited | Professional & scientific | 2025 |
| Asura Ltd | Professional & scientific | 2019 |
| AT & at Properties Ltd | Real estate | 2024 |
| AT Commerce Limited | Wholesale & retail | 2016 |
| AT Electric Contractors Ltd | Construction | 2022 |
| AT Nana's Ltd | Hospitality | 2022 |
| AT One Cars Limited | Wholesale & retail | 2021 |
| Atelier K. Architecture & Design Ltd | Professional & scientific | 2009 |
| Ateno Limited | Hospitality | 2025 |
| Ateres Embroidery London Ltd | Manufacturing | 2024 |
| Athanatech Limited | Information & communication | 2023 |
| Athem Limited | Real estate | 2021 |
| Athena Capital Partners LLP | | 2006 |
| Athlee UK Ltd | Wholesale & retail | 2025 |
| Athnuachan Limited | Information & communication | 2019 |
| Atiar Tilling Ltd | Construction | 2020 |
| Atifaq Food Limited | Wholesale & retail | 2009 |
| Atlantic International Operation Limited | Mining & quarrying | 2005 |
| Atlanticfinds Ltd | Wholesale & retail | 2026 |
| Atlas BMC Limited | Construction | 2016 |
| Atlas Research PLC | | 1971 |
| Atomic Capital Ltd | Real estate | 2025 |