| Aslan Holding Ltd | Real estate | 2026 |
| Aslan Mona Ltd | Construction | 2026 |
| Aslan Property 1 Ltd | Real estate | 2025 |
| Aslanlar Catering Ltd | Hospitality | 2020 |
| ASM London Construction Limited | Construction | 2019 |
| ASM Plumbing & Maintenance Ltd | Construction | 2026 |
| Asman Catering Ltd | Hospitality | 2026 |
| Aspecta Limited | Professional & scientific | 2023 |
| Aspen Grove Limited | Health & social care | 2025 |
| Aspex Residents Association Limited | Households | 2005 |
| Aspire Building and Property Services Ltd | Construction | 2023 |
| Aspire Technologies Software Ltd | Administrative & support | 2016 |
| Aspired Marketing Media Ltd | Manufacturing | 2024 |
| Asprey Capital Limited | Financial services | 2016 |
| ASQ Properties Limited | Real estate | 2016 |
| ASR Capital Ltd | Administrative & support | 2018 |
| ASR Global Co Limited | Manufacturing | 2020 |
| Asrx Ltd | Administrative & support | 2024 |
| Assembly of GOD Missions UK Limited | Other services | 2023 |
| Asset Advisory Ltd | Construction | 2025 |
| ASSETSPHERES@19 Ltd | Information & communication | 2019 |
| Assist Builder Ltd | Construction | 2023 |
| Assist Learning Limited | Education | 2016 |
| Assist to Grow Limited | Health & social care | 2022 |
| Associated Recycling Equipment Limited | Manufacturing | 2025 |
| Associated Response Monthly Ltd | Construction | 2024 |
| Assured Cleaning Solutions Ltd | Administrative & support | 2010 |
| Astech Interiors Limited | Manufacturing | 2002 |
| Astley House Management Company Limited | Real estate | 1997 |
| Aston Cruz Ace & Carter Limited | Real estate | 2017 |
| Astrida Limited | Real estate | 2010 |
| Astute Associates Ltd | Administrative & support | 2022 |
| AT London Ltd | Wholesale & retail | 2025 |
| Atakav Ltd | Other services | 2021 |
| Atar Legal Services Ltd | Professional & scientific | 2019 |
| Atay Limited | Real estate | 2009 |
| ATC Survey Ltd | Administrative & support | 2020 |
| Ates Bakery Ltd | Manufacturing | 2025 |
| Ates ET Ltd | Wholesale & retail | 2026 |
| Atevolve Limited | Other services | 2024 |
| Athalia Ltd | Manufacturing | 2024 |
| Athingofbeauti Ltd | Manufacturing | 2018 |
| Athlyx Ltd | Wholesale & retail | 2025 |
| Athos London Ltd | Other services | 2026 |
| ATI Property Solutions Ltd | Construction | 2023 |
| Atid Estates Ltd | Real estate | 2026 |
| Atif & Imran (A&I) UK Ltd | Wholesale & retail | 2020 |
| Atitoks Limited | Health & social care | 2014 |
| Atlantic Distributions London Limited | Administrative & support | 2011 |
| Atlantic Education Ltd | Information & communication | 2019 |
| Atlantic Property Investments Limited | Real estate | 1995 |
| Atlantic Property Management Limited | Administrative & support | 1998 |
| Atlas Business Utilities Limited | Energy | 2024 |
| Atlas G + M Ltd | Construction | 2018 |
| Atlas London 2018 Ltd | Administrative & support | 2018 |
| Atlas OIL Ltd | Water & waste | 2025 |
| Atlas Property Maintenance Ltd | Households | 2024 |
| Atlas Transport Logistics Limited | Transport & logistics | 2026 |
| Atlas World Foods Limited | Wholesale & retail | 2026 |
| ATM Construction Limited | Construction | 2008 |
| Atos Financial LP | | 2016 |
| ATP Property Solutions Ltd | Construction | 2025 |
| ATS Football Ltd | Arts & recreation | 2023 |
| Attigo Academy Trust | Education | 2018 |
| Attleborough Kebab Limited | Hospitality | 2026 |
| AU Decorating Limited | Construction | 2023 |
| Auctoritas Consulting Limited | Professional & scientific | 2014 |
| Audi Transport Ltd | Transport & logistics | 2025 |
| Auntie's Street Food Ltd | Hospitality | 2025 |
| Aura Essences Ltd | Wholesale & retail | 2019 |
| Aura Hair & Beauty Studio Limited | Other services | 2025 |
| Aura Streaming Ltd | Information & communication | 2025 |
| Aurelia Trade Ltd | Wholesale & retail | 2025 |
| Aurora Capital Venture Limited | Real estate | 2022 |
| Aurora's Glow Ltd | Manufacturing | 2026 |
| Austin Butler Ltd. | Administrative & support | 2015 |
| Australplay Ltd | Other services | 2015 |
| Austrian Ltd | Wholesale & retail | 2023 |
| Authentic Logistics Limited | Transport & logistics | 2020 |
| Authentic Origins Limited | Wholesale & retail | 2025 |
| Authentic RAY Logistics Limited | Administrative & support | 2024 |
| Auto Assist Plus Ltd | Construction | 2018 |
| Auto Cat Limited | Wholesale & retail | 2019 |
| Auto Junior Car Ltd | Wholesale & retail | 2025 |
| Auto Repair Group Ltd | Wholesale & retail | 2018 |
| Auto Technic London Limited | Wholesale & retail | 2019 |
| Automotive Components Specialist Ltd | Wholesale & retail | 2011 |
| Autotube.Vip Ltd | Information & communication | 2026 |
| Autoxai Community C.I.C. | Information & communication | 2025 |
| Autumn Money Group Ltd | Financial services | 2025 |
| AV Unlimited UK Ltd | Administrative & support | 2022 |
| AVA Properties London Ltd | Real estate | 2025 |
| Ava-M Property Ltd | Real estate | 2022 |
| Avaka Limited | Real estate | 2021 |
| Avant Real Estates Ltd | Real estate | 2022 |
| Avaris Investments Limited | Real estate | 2025 |
| Avatarya Ltd | Wholesale & retail | 2023 |
| AVC 2018 Ltd | Manufacturing | 2018 |
| AVC Enterprise (London) Ltd | Professional & scientific | 2025 |
| AVE Ciya Ltd | Wholesale & retail | 2026 |