| Ascot Celebrity Canines Limited | Extraterritorial | 2014 |
| Ascot Intelligence Ltd | Administrative & support | 2014 |
| Asea Holdings Limited | Real estate | 2022 |
| Asea Homes Limited | Real estate | 2025 |
| ASF Cleaning Ltd | Administrative & support | 2021 |
| Asfan Business Services Limited | Professional & scientific | 2017 |
| ASH Electrical Ltd | Construction | 2018 |
| Ashbees 100 Limited | Wholesale & retail | 2020 |
| Ashdon Online Limited | Other services | 2023 |
| Ashdon Refurbishments Limited | Real estate | 2021 |
| Ashford Utilities Limited | Construction | 2017 |
| Ashlan Technology Ltd | Professional & scientific | 2013 |
| Ashmore International Limited | Professional & scientific | 2020 |
| Ashwell UK Estates Limited | Real estate | 2022 |
| Ashwood House Limited | Administrative & support | 1998 |
| Asianet (Europe) Ltd. | Information & communication | 2003 |
| Asif Hussain Advisory Limited | Professional & scientific | 2021 |
| Asim Traders Ltd | Wholesale & retail | 2018 |
| Askria Ltd | Information & communication | 2020 |
| ASL Projects Ltd | Construction | 2024 |
| Asleepholdings Limited | Manufacturing | 2024 |
| Asleeptrading Limited | Manufacturing | 2024 |
| Asme Limited | Real estate | 2023 |
| Asopis Consulting Ltd | Professional & scientific | 2016 |
| Aspc Limited | Real estate | 2024 |
| Aspire Realty Ltd | Real estate | 2019 |
| Aspireed Advisors Ltd | Education | 2025 |
| Asrb Ltd | Health & social care | 2015 |
| Assembly & Packaging Services Ltd | Manufacturing | 1989 |
| Asset Properties (One) Limited | Real estate | 2008 |
| Assuredq Ltd | Professional & scientific | 2022 |
| Aston Information Security Limited | Administrative & support | 2004 |
| Astons (JWR) Ltd | Other services | 2017 |
| Astralis Capital Ltd | Financial services | 2024 |
| Astralyz Ltd | Information & communication | 2025 |
| Astrix Electrical Contractors Limited | Construction | 2006 |
| Astute Marketeers Ltd | Professional & scientific | 2013 |
| Asyz Intvestment & Trading Group Limited | Real estate | 2025 |
| Atalica Properties Limited | Construction | 2015 |
| ATD Research and Consultancy Ltd | Professional & scientific | 2015 |
| ATE Property Investments Limited | Real estate | 2026 |
| Atelier AU Limited | Professional & scientific | 2017 |
| ATI Pharmaceuticals Limited | Wholesale & retail | 2015 |
| Atkins Physiotherapy Consultants Limited | Health & social care | 2015 |
| Atlantica Transport Ltd | Transport & logistics | 2023 |
| Atlantis Builders Ltd | Construction | 2023 |
| Atlantis Consulting Ltd | Professional & scientific | 2017 |
| Atlas Rise Limited | Arts & recreation | 2023 |
| Atlas Transformation Limited | Information & communication | 2020 |
| Atma Croydon Ltd | Real estate | 2021 |
| Atoko Ltd | Manufacturing | 2018 |
| Atom Training and Recruitment Limited | Construction | 2008 |
| Atomgeo UK Limited | Information & communication | 2022 |
| Atoz Mart Ltd | Wholesale & retail | 2023 |
| Atraum Dunamis Ltd | Wholesale & retail | 2022 |
| Atrium Fitness Ltd | Arts & recreation | 2008 |
| Attune & Insight Ltd | Health & social care | 2026 |
| AUM (2020) Limited | Real estate | 2020 |
| Aura Care Solutions Ltd | Health & social care | 2025 |
| Aura Salon Furniture Ltd | Wholesale & retail | 2024 |
| Auralumeo Ltd | Wholesale & retail | 2025 |
| Aurevia Service Group Ltd | Administrative & support | 2026 |
| Aurora's Daisy Chain Ltd | Professional & scientific | 2026 |
| Auroras Properties Limited | Real estate | 2024 |
| Auryn Ltd | Professional & scientific | 2019 |
| Austin Eyewear LLP | | 2005 |
| Automotive Component Marketing Limited | Real estate | 1986 |
| Autoshine Global UK Ltd | Wholesale & retail | 2026 |
| Avades Consulting Limited | Information & communication | 2018 |
| Avalen Partners Limited | Financial services | 2026 |
| Avdeaf Lettings Limited | Real estate | 2016 |
| Avdime Limited | Financial services | 2013 |
| Aventio Ltd | Professional & scientific | 2014 |
| Aventurine Ltd | Real estate | 2020 |
| Aver House Developments Ltd | Construction | 2018 |
| Averra Capital Ltd | Health & social care | 2026 |
| Avicenna Health Limited | Health & social care | 2014 |
| Avintagefit Limited | Manufacturing | 2022 |
| Avitech Investments Limited | Real estate | 2018 |
| AVN Marine Solutions Limited | Administrative & support | 2019 |
| AVN Solutions (Holdings) Ltd | Administrative & support | 2023 |
| AVN Solutions (UK) Limited | Administrative & support | 2013 |
| Avocado Food Ltd | Wholesale & retail | 2017 |
| Avon Asset Management Limited | Real estate | 2013 |
| Avon Estates (Europe) Limited | Real estate | 2019 |
| Avon House Limited | Extraterritorial | 2018 |
| Avshine Lettings Limited | Real estate | 2016 |
| Avtone Properties Limited | Construction | 2012 |
| AVU Properties Limited | Real estate | 2025 |
| Awareness 360 Global | Education | 2026 |
| AWD Recruitment Limited | Administrative & support | 2006 |
| AX Contracting Ltd | Administrative & support | 2014 |
| Axis PM Limited | Professional & scientific | 2024 |
| AY Probuild Limited | Construction | 2026 |
| Ayaan TEJ Homes Ltd | Real estate | 2021 |
| Ayad Investments Ltd | Real estate | 2023 |
| Ayad Property Holdings Limited | Real estate | 2021 |
| Ayat Ayman Traders Limited | Wholesale & retail | 2026 |
| Ayatayman Transport Company Limited | Transport & logistics | 2024 |
| Ayesda BIO Limited | Professional & scientific | 2025 |