| Astral Estates Ltd | Real estate | 2026 |
| Astro Lettings Ltd | Real estate | 2011 |
| Astro Property Management Limited | Households | 2013 |
| Astro Residential Ltd | Households | 2015 |
| Astro Residential Properties, Lettings and Management Ltd | Real estate | 2018 |
| Astro SA Properties Ltd | Real estate | 2019 |
| Astute Integrated Services Ltd | Administrative & support | 2025 |
| Asutoro Group Ltd | Wholesale & retail | 2021 |
| ASW Spinal Experts Ltd | Health & social care | 2022 |
| Aswani Consulting Limited | Information & communication | 2026 |
| AT & PF Limited | Administrative & support | 2009 |
| AT Advisory Limited | Professional & scientific | 2025 |
| AT and Associates Limited | Information & communication | 2008 |
| AT DTC Limited | Wholesale & retail | 2026 |
| AT Gostenski Group Ltd | Financial services | 2025 |
| ATE Capital Limited | Real estate | 2024 |
| ATE Investment Limited | Information & communication | 2020 |
| Atelier Ventus Ltd | Wholesale & retail | 2025 |
| Atharva Modi Ltd | Real estate | 2023 |
| Athena Dynamix Limited | Administrative & support | 2022 |
| Athena IT Solutions Ltd | Information & communication | 2024 |
| Athis Endo Ltd | Health & social care | 2020 |
| Atinshola Ltd | Information & communication | 2015 |
| Atko Consultancy Ltd | Professional & scientific | 2023 |
| Atlantis Tanks Group Ltd | Wholesale & retail | 2016 |
| Atlantis Tanks Holdings Limited | Wholesale & retail | 2024 |
| Atlas Codes Ltd | Information & communication | 2018 |
| Atlas Consultants Ltd | Wholesale & retail | 2025 |
| Atlas Fortis Ltd | Wholesale & retail | 2025 |
| Atlas Strategic Solutions Limited | Administrative & support | 2019 |
| Atlas Talent Group Ltd | Professional & scientific | 2025 |
| Atmos Security Ltd | Real estate | 2022 |
| Atmosphee Ltd | Other services | 2023 |
| ATO Homes Ltd | Real estate | 2024 |
| Atomix Intelligent Finance Ltd | Financial services | 2022 |
| Atomix Investments Ltd | Financial services | 2026 |
| Aton Property Group Limited | Wholesale & retail | 2022 |
| Atozgas Ltd | Manufacturing | 2019 |
| ATP Locksmith Ltd | Manufacturing | 2025 |
| Atre Life Limited | Wholesale & retail | 2024 |
| Atrium Residential Limited | Real estate | 2004 |
| ATT Advanced Control Technology Ltd | Manufacturing | 2026 |
| Attain Tutors Limited | Education | 2020 |
| Attalus CC Ltd | Professional & scientific | 2026 |
| Attentive Property Services Ltd | Construction | 2024 |
| Attren. Ltd | Wholesale & retail | 2022 |
| Attribution Booster Ltd | Information & communication | 2025 |
| Attune Space Ltd | Professional & scientific | 2026 |
| ATW Valets Limited | Administrative & support | 2024 |
| Atxpert Ltd | Professional & scientific | 2024 |
| Atyang Ltd | Wholesale & retail | 2018 |
| AU Customs Ltd | Manufacturing | 2023 |
| Aubrey Powell Consulting (APC) Limited | Professional & scientific | 2025 |
| Auctionlens Limited | Information & communication | 2026 |
| Audacity International Ltd | Professional & scientific | 2026 |
| Audio Assistance Limited | Information & communication | 2026 |
| Audio Rebel Project CIC | Education | 2025 |
| Auditsphere Ltd | Information & communication | 2025 |
| AUF Group Ltd | Wholesale & retail | 2022 |
| Augmatic Ltd | Extraterritorial | 2024 |
| Augzy Ltd | Wholesale & retail | 2026 |
| Aunt Marys Ltd | Wholesale & retail | 2025 |
| Aura Psychology Ltd | Health & social care | 2023 |
| Aura&Lx Ltd | Wholesale & retail | 2026 |
| Aurae Club Ltd | Manufacturing | 2024 |
| Aurah Ltd | Other services | 2022 |
| Auralink Universe Ltd | Wholesale & retail | 2025 |
| Auramind Care Ltd | Health & social care | 2025 |
| Aurbi Limited | Wholesale & retail | 2012 |
| Aurelius Retail Limited | Wholesale & retail | 2024 |
| Aureon Estates Ltd | Real estate | 2023 |
| Aurestone Holding Limited | Financial services | 2026 |
| Aurestone Property Limited | Real estate | 2026 |
| Aurexus Group Ltd | Information & communication | 2026 |
| Auricle EAR Care Limited | Health & social care | 2026 |
| Auriga Industries Ltd | Professional & scientific | 2023 |
| Aurora Global Business Ltd | Manufacturing | 2026 |
| Aurora International Foundation CIC | Professional & scientific | 2026 |
| Aurora Investments Group Ltd | Real estate | 2025 |
| Aurora Shihtzu Ltd | Agriculture & fishing | 2026 |
| Aurorai Ltd | Information & communication | 2025 |
| Aurum Green Ltd | Professional & scientific | 2025 |
| Aurum Recruitment Ltd | Administrative & support | 2025 |
| Austar Global Limited | Wholesale & retail | 2017 |
| Auster Place Apartments (Brightwell Lakes) Residents Management Company Limited | Households | 2025 |
| Austin Knight Consulting Ltd. | Extraterritorial | 2014 |
| Austin Media Consulting Ltd | Administrative & support | 2014 |
| Austin Page Retail Ltd | Wholesale & retail | 2023 |
| Austin Professional Services (APS) Limited | Professional & scientific | 2025 |
| Authentic Sounds Limited | Information & communication | 2025 |
| Authenticallyou Ltd | Health & social care | 2021 |
| Authory-App Ltd | Wholesale & retail | 2023 |
| Autistic-Thoughts Ltd | Professional & scientific | 2021 |
| Auto Airports Executive Cars Ltd | Transport & logistics | 2025 |
| Auto Gearbox Repairs Ltd | Wholesale & retail | 2026 |
| Autocue Limited | Professional & scientific | 2009 |
| Autoferret Ltd | Wholesale & retail | 2026 |
| Autohub MD Limited | Information & communication | 2026 |
| Autolink Logistics Ltd | Transport & logistics | 2025 |
| Automatic Growth Limited | Professional & scientific | 2026 |