| ARX Services Ltd | Wholesale & retail | 2022 |
| Asal Management Ltd | Professional & scientific | 2017 |
| Asal Motor Group Ltd | Wholesale & retail | 2017 |
| Asbjj Ltd | Arts & recreation | 2024 |
| Ascentra Consulting Limited | Information & communication | 2025 |
| Ashanti Events Ltd | Hospitality | 2020 |
| Ashbang Films Ltd | Information & communication | 2023 |
| Ashcroft Capital Europe Limited | Professional & scientific | 2024 |
| Ashicca Ltd | Wholesale & retail | 2022 |
| Ashleigh Residents (Horsham) Limited | Households | 2007 |
| Ashman Express Ltd | Wholesale & retail | 2020 |
| Ashton Davis Electrical Limited | Wholesale & retail | 1963 |
| Asiana Cars Limited | Other services | 2013 |
| Aslan Dynamics Limited | Administrative & support | 2025 |
| Aslans Property Development & Maintenance Ltd | Real estate | 2023 |
| Asmi Wellness Limited | Health & social care | 2025 |
| Aspect Construction Solutions Ltd | Construction | 2024 |
| Aspects Mediation Services Ltd | Administrative & support | 2025 |
| Aspire Commercial Contractors Ltd | Construction | 2010 |
| Aspire Facades Ltd | Construction | 2020 |
| Aspire Fire Doors Ltd | Construction | 2023 |
| Aspire Homebuild Ltd | Construction | 2019 |
| Association for Clinical Theological Training and Care Limited(The) | Education | 1962 |
| Assure Occupational Therapy Services Ltd | Health & social care | 2026 |
| Asten Limited | Wholesale & retail | 1998 |
| Aston Dove Limited | Construction | 1988 |
| Astounding Entertainment Ltd | Arts & recreation | 2022 |
| Astriza UK Ltd | Wholesale & retail | 2014 |
| Astute Property Acquisitions Corporation Limited | Financial services | 2016 |
| AT 3 Limited | Hospitality | 2025 |
| AT Cars Gatwick Ltd | Transport & logistics | 2021 |
| AT Scale Limited | Professional & scientific | 2017 |
| ATA Groundworks Ltd | Administrative & support | 2024 |
| ATC Group Limited | Professional & scientific | 2000 |
| Athelstan Management Company Limited | Real estate | 2004 |
| Athene Management LLP | | 2009 |
| Atlantic Picture Company Ltd | Information & communication | 2006 |
| Atlantic Solway Holdings Limited | Professional & scientific | 2013 |
| Atms Services Ltd | Wholesale & retail | 2025 |
| Atms Support Ltd | Wholesale & retail | 2026 |
| Ato&Mir Ltd | Hospitality | 2025 |
| Atoyota (Holdings) Limited | Professional & scientific | 2000 |
| Ats-One Limited | Transport & logistics | 2014 |
| Attollere Ltd | Professional & scientific | 2018 |
| Au&P Services Ltd | Administrative & support | 2025 |
| Aukers Ltd | Real estate | 2023 |
| Aura GAS Ltd | Construction | 2025 |
| Aurelius Accelerate Limited | Professional & scientific | 2010 |
| AUTO66 Ltd | Wholesale & retail | 2022 |
| Automatics Tooling Company Limited | Manufacturing | 1952 |
| Automotive Xpress Ltd | Wholesale & retail | 2023 |
| Autone Solutions Ltd | Information & communication | 2026 |
| Autoquest Redhill Limited | Wholesale & retail | 2017 |
| Autoshield JOG Limited | Wholesale & retail | 2013 |
| Autoteck Accessories Ltd. | Wholesale & retail | 2017 |
| AV8 Productions Limited | Professional & scientific | 2004 |
| Avanir Boba Ltd | Wholesale & retail | 2025 |
| Avanos Medical UK Limited | Wholesale & retail | 2014 |
| Avenue Building Company Limited | Construction | 1998 |
| Avenue Court Limited | Households | 2007 |
| Avery Drive Management Company Limited | Households | 2019 |
| AVI Construction Group Ltd | Real estate | 2020 |
| Avisado Care Limited | Health & social care | 2020 |
| Awesome Props Ltd | Information & communication | 2014 |
| AX Creative Ltd | Professional & scientific | 2023 |
| AXA Assistance (U.K.) Limited | Financial services | 1991 |
| AXA Travel Insurance Limited | Financial services | 2010 |
| Axiom Testing Ltd | Information & communication | 2026 |
| Axyle Corporation Ltd | Information & communication | 2021 |
| AY Clark Limited | Professional & scientific | 2014 |
| Ayambrar Limited | Wholesale & retail | 2023 |
| Azar(Uk) Limited | Construction | 2022 |
| B & L Utilities Ltd. | Construction | 2015 |
| B & R Management Limited | Financial services | 1990 |
| B Inspired Property Solutions Limited | Construction | 2024 |
| B&Eks Social Work Limited | Professional & scientific | 2023 |
| B&F Wharf Developments Limited | Real estate | 2024 |
| B&L Lift Laminations Ltd | Construction | 2025 |
| B.D.J. Estates Limited | Administrative & support | 2000 |
| B2G Leisure Limited | Hospitality | 2016 |
| Bailey C Limited | Extraterritorial | 2012 |
| Bailey Housing Consultancy LLP | | 2012 |
| Baines ORR (London) Limited | Wholesale & retail | 1970 |
| Balglad Residents Company Limited | Households | 1977 |
| Ball Transport Ltd | Administrative & support | 2025 |
| Ballast Nedam Construction Limited | Construction | 2017 |
| Ballast Nedam UK Ltd | Financial services | 2022 |
| Balmoral Health Solutions Ltd | Wholesale & retail | 2025 |
| Bamboo Club Ltd | Wholesale & retail | 2019 |
| Bamboo HUT Catering Limited | Hospitality | 2013 |
| Bamrec Limited | Professional & scientific | 2018 |
| Bantony Ltd | Health & social care | 2012 |
| Banwait Property Limited | Real estate | 2020 |
| Bar TUR Photo Award / Picturestories Fund | Professional & scientific | 2023 |
| Barkwear London Ltd | Manufacturing | 2025 |
| Barry Hair Fashions Limited | Other services | 2007 |
| Baseline Airconditioning UK Ltd | Construction | 2014 |
| Basic Healthcare Ltd | Health & social care | 2019 |
| BAT Construction Services Limited | Professional & scientific | 2019 |
| BAT Property Limited | Construction | 2021 |