| Aset Science Ltd | Extraterritorial | 2014 |
| Asfba Ltd | Wholesale & retail | 2025 |
| Ashley Spivack Physiotherapy Limited | Health & social care | 2003 |
| Ashmere Partners Limited | Information & communication | 2012 |
| Ashtavinayaka Tech Ltd | Information & communication | 2023 |
| Ashton Gate Financial Limited | Financial services | 2008 |
| Ashwood & Blake Ltd | Real estate | 2010 |
| Asia Academy of Existentialism Group | Administrative & support | 2023 |
| Asia Magnesite Chemical Co., Ltd | Wholesale & retail | 2020 |
| Asia Pacific Medical Ltd | Wholesale & retail | 2014 |
| Asia Star Import and Export Co., Ltd | Wholesale & retail | 2018 |
| Asian Ameri-Trader Limited | Wholesale & retail | 2022 |
| Asian Linqtex Company Limited | Wholesale & retail | 2023 |
| Asian Medical Press Limited | Information & communication | 2023 |
| Asian Visionary Partners Co., Ltd | Extraterritorial | 2014 |
| Asiatic Marine and Trading PTE. Ltd | Manufacturing | 2024 |
| Asier Lighting Solution Limited | Manufacturing | 2024 |
| Asio Projects Limited | Professional & scientific | 2017 |
| Asit Technology Co., Ltd. | Manufacturing | 2021 |
| Askeko Ltd | Hospitality | 2018 |
| ASM UK Logistics Ltd | Transport & logistics | 2025 |
| ASN High Tech Limited | Extraterritorial | 2022 |
| Asnad AL Furat AL Awsat Company Ltd | Construction | 2023 |
| ASO Yoruba Heritage Limited | Wholesale & retail | 2021 |
| Asoftake Co., Ltd | Extraterritorial | 2015 |
| Asone Design Limited | Information & communication | 2005 |
| Asora Select Limited | Administrative & support | 2026 |
| Aspire Lettings Limited | Real estate | 2016 |
| Aspire Solutions Limited | Information & communication | 2010 |
| Asta Construction Ltd | Construction | 2025 |
| Astermon U.K. Company Ltd. | Manufacturing | 2025 |
| Astonmill Trading Limited | Transport & logistics | 2024 |
| Astra Technovation Private Limited | Wholesale & retail | 2021 |
| Astraway Construction Limited | Construction | 2011 |
| Astromil Limited | Real estate | 2011 |
| Astronoir Ltd | Professional & scientific | 2022 |
| Asure Biochem Co., Ltd | Extraterritorial | 2020 |
| AT & NT Limited | Manufacturing | 2012 |
| AT Kent House Limited | Hospitality | 2026 |
| At&M Co., Ltd | Extraterritorial | 2019 |
| ATA Europe Technology Ltd | Information & communication | 2024 |
| Atecc Co., Ltd | Manufacturing | 2015 |
| Atelier Grosgrain Ltd | Professional & scientific | 2025 |
| Ates Mangal Meze Bar Ltd | Hospitality | 2022 |
| ATF Power UK Company Limited | Manufacturing | 2025 |
| Athena Biomedical Corp. Ltd | Wholesale & retail | 2024 |
| Athena Cosmetix Limited | Other services | 2022 |
| Atlantic International Group UK Co., Ltd. | Wholesale & retail | 2024 |
| Atlantic Ocean International Limited | Extraterritorial | 2019 |
| Atlas Internation Co., Ltd. | Manufacturing | 2023 |
| Atlas Payroll & Administration Ltd | Administrative & support | 2025 |
| Atlas Rubber Import&Export Ltd | Extraterritorial | 2023 |
| Ato-Tours Limited | Administrative & support | 2017 |
| Attwood Real Estate Limited | Real estate | 2026 |
| Atwork GP Ltd | Health & social care | 2023 |
| Aubin Holdings Limited | Financial services | 2022 |
| Audenca Limited | Administrative & support | 2017 |
| Auldmay K Elan Ltd | Agriculture & fishing | 2013 |
| Auntie MAY Limited | Hospitality | 2017 |
| Auntie MAY Takeaway Limited | Hospitality | 2021 |
| Aura Beauty Treatments Ltd | Other services | 2018 |
| Aureasia UK Brands Ltd | Extraterritorial | 2025 |
| Aurora MAX UK Limited | Manufacturing | 2024 |
| Aurya Limited | Information & communication | 2018 |
| Auspic Pearls Limited | Extraterritorial | 2019 |
| Aussielab Australia Study Abroad Limited | Education | 2025 |
| Australian Marine Life Group Ltd | Manufacturing | 2021 |
| Austria Grieg Piano Group Ltd | Extraterritorial | 2018 |
| Autel Robotics UK Limited | Professional & scientific | 2022 |
| Autocar Industry Ltd | Extraterritorial | 2021 |
| Autocentre Engineering Services Limited | Wholesale & retail | 2000 |
| Autocure Limited | Wholesale & retail | 2003 |
| Autoknit Industry Co., Ltd | Extraterritorial | 2019 |
| Automax Industry Co., Ltd | Extraterritorial | 2006 |
| Automold Ltd. | Extraterritorial | 2024 |
| Autopart Manufacture Co., Limited | Manufacturing | 2022 |
| Autos International Holding Co., Ltd. | Manufacturing | 2015 |
| Autrise Group Limited | Extraterritorial | 2018 |
| AV Outcomes Ltd | Other services | 2013 |
| AV Systems Services Ltd | Manufacturing | 2023 |
| Av-Outsource Limited | Information & communication | 2002 |
| Avanza Medical Limited | Health & social care | 2021 |
| Avel Limited | Information & communication | 2015 |
| Avenella Group Ltd | Professional & scientific | 2021 |
| Avenue of Star Co., Ltd | Extraterritorial | 2023 |
| Aviemore Management Limited | Financial services | 2009 |
| Avignon Road Developments Ltd | Construction | 2017 |
| Avision Building Contractors Ltd | Construction | 2022 |
| Avita Build Ltd | Construction | 2023 |
| Avita Tech Ltd | Construction | 2012 |
| Avolasca International Co., Limited | Manufacturing | 2026 |
| Avondale Rest Ltd | Wholesale & retail | 2024 |
| Avonstowe Limited | Professional & scientific | 2022 |
| Avus FIX Ltd | Other services | 2015 |
| Awans Investments(Beckenham) Ltd | Wholesale & retail | 2014 |
| Awendiesel Power Co., Ltd | Extraterritorial | 2012 |
| Awesome Supply Chain Ltd. | Wholesale & retail | 2021 |
| Awssun Co., Ltd | Extraterritorial | 2016 |
| Axcess Doors Co Limited | Manufacturing | 2024 |
| Axis Roofing London Ltd | Construction | 2025 |