| Ashmead Homes Limited | Real estate | 2019 |
| Ashmeadow Property Management Company Limited | Households | 2005 |
| Ashniya Limited | Real estate | 2018 |
| Ashore Property Management Ltd | Real estate | 2018 |
| Ashpri Limited | Health & social care | 2010 |
| Ashtree Villa Limited | Real estate | 2024 |
| Ashurst Associates Limited | Other services | 2019 |
| Ashwell Convenience Store T/As Hauxton Village Store Ltd | Wholesale & retail | 2019 |
| Ashwell Road Developments Ltd | Hospitality | 2025 |
| Ashwood Carwash Ltd | Administrative & support | 2026 |
| Ashwood Chiropractic Clinic Limited | Health & social care | 2014 |
| Ashwood Kitchens & Interiors Limited | Construction | 2026 |
| Asia Mini Market Ltd | Wholesale & retail | 2019 |
| Asia MM Ltd | Wholesale & retail | 2023 |
| Asiagkos Ltd | Wholesale & retail | 2025 |
| Asil Property Ltd | Real estate | 2026 |
| ASK Invest Ltd | Real estate | 2021 |
| ASK Pro IT Solutions Ltd | Information & communication | 2022 |
| Askari Medical Ltd | Health & social care | 2025 |
| Askari Properties Ltd | Real estate | 2024 |
| Askium Limited | Information & communication | 2010 |
| Askkd Investment Limited | Real estate | 2023 |
| Askkd Limited | Real estate | 2014 |
| Askyourway Ltd | Hospitality | 2020 |
| ASM Care Ltd | Health & social care | 2025 |
| ASN Globe Enterprises Ltd | Wholesale & retail | 2024 |
| ASO Fast Food Ltd | Hospitality | 2023 |
| Asons Trader Private Ltd | Wholesale & retail | 2025 |
| Aspenwood Holdings Ltd | Real estate | 2024 |
| Asper International Limited | Wholesale & retail | 2018 |
| Aspire Parkour Academy Ltd | Education | 2019 |
| Asprey Facilities Ltd | Real estate | 2019 |
| Asqit Ltd | Information & communication | 2018 |
| ASR Autobreakers Ltd | Wholesale & retail | 2015 |
| Asset Bridge Ltd | Financial services | 2025 |
| Asset Earning Power Arena (Aepa) Ltd | Construction | 2021 |
| Asset Earning Power Group (Aepg) Ltd | Construction | 2020 |
| Asset Earning Power Land (Aepl) Ltd | Construction | 2021 |
| Asset Earning Power Residential (Aepr) Ltd | Construction | 2021 |
| Asset House Management Ltd | Administrative & support | 2025 |
| Asset Investing Ltd | Hospitality | 2018 |
| Assigned Healthcare Solutions Limited | Health & social care | 2023 |
| Assisted Transit Ltd | Transport & logistics | 2024 |
| Assl Ltd | Administrative & support | 2025 |
| Associated Cars & Commercials Ltd | Wholesale & retail | 2003 |
| Associated Catering Equipment Limited | Manufacturing | 2022 |
| Associated Taxis Ltd | Transport & logistics | 2019 |
| Association of Fencing Industries | Other services | 2016 |
| Association of Manufacturers of Power Generating Systems (Amps) | Other services | 1989 |
| Assure GAS Solutions Limited | Professional & scientific | 2014 |
| Assured 24/7 Ltd | Health & social care | 2011 |
| Assured Accountants Limited | Professional & scientific | 2021 |
| Assured Quality Solutions Ltd | Professional & scientific | 2009 |
| AST Carcare Limited | Wholesale & retail | 2021 |
| AST96 Limited | Wholesale & retail | 2022 |
| ASTAR1 Care Agency Limited | Health & social care | 2022 |
| Aste Ltd | Wholesale & retail | 2023 |
| Astoria Accountants Limited | Professional & scientific | 2024 |
| Astrocade Ltd | Arts & recreation | 2025 |
| Asynmi Ltd | Professional & scientific | 2024 |
| Aszm Ltd | Real estate | 2023 |
| AT Bespoke Installs Limited | Construction | 2025 |
| AT Express Ltd | Wholesale & retail | 2019 |
| AT Extranutri Ltd | Wholesale & retail | 2023 |
| AT Home Services Cambs Ltd. | Other services | 2010 |
| AT Installation Services Limited | Construction | 2019 |
| AT Primebio Ltd | Wholesale & retail | 2025 |
| ATAL123 Ltd | Hospitality | 2026 |
| ATB Electrical Services Ltd | Manufacturing | 2008 |
| ATD Vehicle Specialists Ltd | Wholesale & retail | 2021 |
| Atelier 109 Limited | Wholesale & retail | 2003 |
| ATH Project Solutions Ltd | Information & communication | 2021 |
| Athelstan Solutions Ltd | Information & communication | 2021 |
| Athena & Marie Ltd | Health & social care | 2015 |
| Athos Development Services Ltd | Financial services | 2020 |
| Atif Enterprises Ltd | Wholesale & retail | 2025 |
| Atlantic Cedar Limited | Professional & scientific | 2005 |
| Atlantic Couriers Ltd | Transport & logistics | 2020 |
| Atlantic Developers Ltd | Construction | 2022 |
| Atlantic Ltd Store Limited | Wholesale & retail | 2023 |
| Atlas Care Services Ltd | Health & social care | 2007 |
| Atlas Engineering LLC Limited | Information & communication | 2020 |
| Atlas GEO- Data Ltd | Professional & scientific | 2014 |
| Atlas Mapping Limited | Information & communication | 2010 |
| Atnep Brand Ltd | Wholesale & retail | 2024 |
| Atolla Swim Limited | Wholesale & retail | 2026 |
| Atom Minds Ltd | Information & communication | 2025 |
| Atomatic Limited | Information & communication | 2016 |
| Atomcamp Limited | Information & communication | 2024 |
| Atomic Goats Ltd | Information & communication | 2026 |
| Atora Terra Ltd | Real estate | 2023 |
| Atoz Plumbing Ltd | Construction | 2022 |
| ATP Access Platforms Ltd | Construction | 1997 |
| ATS Internet Consultancy Limited | Information & communication | 2003 |
| Attagrata Ltd | Information & communication | 2025 |
| Attah Innovation Group Limited | Administrative & support | 2023 |
| Atwal Solutions Ltd | Transport & logistics | 2011 |
| ATZ Medical Ltd | Health & social care | 2015 |
| Au-Yeung and Tsang Holding Limited | Manufacturing | 2025 |
| Aubrey Helm Ltd | Professional & scientific | 2020 |