| Anjin Consultancy Ltd | Information & communication | 2015 |
| Annabeth Limited | Hospitality | 1976 |
| Annie Barker Media Limited | Information & communication | 2018 |
| Antony Roberts Estate Agents Limited | Real estate | 1998 |
| Anugraha Beneficial Holdings & Investments Ltd | Real estate | 2025 |
| Aperiter Ltd | Information & communication | 2026 |
| Apex Networks Holdings Limited | Financial services | 2017 |
| Apex Networks Limited | Information & communication | 2005 |
| Apex UK Distributors Limited | Wholesale & retail | 2024 |
| Aphl 2 Limited | Administrative & support | 2018 |
| Apollo II Limited | Wholesale & retail | 2007 |
| Apothany Ltd. | Information & communication | 2021 |
| Appetite 4 Recruitment Ltd | Administrative & support | 2003 |
| Appetite 4 Work Limited | Administrative & support | 2015 |
| Appliance Expert Ltd | Manufacturing | 2009 |
| Apro Project Services Limited | Real estate | 2012 |
| Aqaversant Ltd | Information & communication | 2021 |
| Aquaplus Limited | Professional & scientific | 2015 |
| Aquaurum Ltd | Professional & scientific | 2012 |
| Aquila Property Limited | Construction | 2023 |
| Arakoola Investments Limited | Financial services | 2026 |
| Arbb Ltd | Professional & scientific | 2024 |
| Arbortech Limited | Agriculture & fishing | 2012 |
| Arbour (Priorsfield) Management Company Limited | Households | 2000 |
| ARC Project Services (London) Limited | Professional & scientific | 2016 |
| Arch Corporation Limited | Extraterritorial | 2013 |
| Arcturus Analytics Limited | Information & communication | 2013 |
| Area Holdings Limited | Real estate | 2016 |
| Area Project Management Ltd | Professional & scientific | 2002 |
| Argor LED Lighting Ltd | Wholesale & retail | 2014 |
| ARK BC Limited | Professional & scientific | 2013 |
| ARK Investment Advisers Ltd | Financial services | 2020 |
| ARK Quantity Surveying Ltd | Professional & scientific | 2024 |
| Aroma 26 Limited | Hospitality | 2025 |
| Arsp Property Investment Ltd | Financial services | 2021 |
| Art Intense Ltd | Arts & recreation | 2021 |
| Art of DOM Ltd | Arts & recreation | 2024 |
| Artene Limited | Information & communication | 2023 |
| Artillery Road Group Limited | Households | 2020 |
| Arun Ventura Limited | Information & communication | 2023 |
| Arvendale Ltd | Information & communication | 2026 |
| Arvy Construction & Renovations Ltd | Extraterritorial | 2023 |
| Asepsis Innovations Ltd | Education | 2026 |
| Ashley Capital Limited | Real estate | 2017 |
| Asilia Africa UK Ltd | Administrative & support | 2019 |
| ASO Pro Ltd | Construction | 2023 |
| Asobi-K Design Ltd | Information & communication | 2015 |
| ASP Building and Renovation Ltd | Construction | 2021 |
| Aspect Wealth Ltd | Professional & scientific | 2019 |
| Aspire Pharma Limited | Wholesale & retail | 2009 |
| Asset FLO Limited | Information & communication | 2025 |
| Assetlogic International Ltd | Information & communication | 2021 |
| Assetwide Limited | Wholesale & retail | 2010 |
| Assumpsit Consultancy Ltd | Professional & scientific | 2011 |
| Astel Ventures Ltd | Administrative & support | 2020 |
| Astuta Ltd | Professional & scientific | 2011 |
| Atheldene Estates Limited | Real estate | 2004 |
| Atlantic Technology Limited | Manufacturing | 2016 |
| Atlas Design Ltd | Real estate | 2022 |
| Atlas Seven Productions Ltd | Information & communication | 2024 |
| Atom MQ Services Limited | Information & communication | 2016 |
| Atomusicality LLP | | 2019 |
| Auga Technologies Limited | Information & communication | 2006 |
| Aura Life Limited | Information & communication | 2019 |
| Auriga Labs Limited | Information & communication | 2003 |
| Austell Investments Limited | Administrative & support | 1994 |
| Austen Estates Group Ltd | Financial services | 2021 |
| Austen Estates Limited | Real estate | 2016 |
| Australasian and General Securities Limited | Administrative & support | 1971 |
| AUT Tick Ltd | Information & communication | 2024 |
| Authentic Apartments Ltd | Real estate | 2024 |
| Authenticity Works Ltd | Administrative & support | 2026 |
| Authors of Change Ltd | Extraterritorial | 2012 |
| Auto Cruising Ltd | Financial services | 2025 |
| Automotion Events Ltd | Administrative & support | 2019 |
| Avectra Aircraft Developement Ltd | Manufacturing | 2016 |
| Aveley Conveyancing Limited | Professional & scientific | 2005 |
| Avendiss Consulting Ltd | Professional & scientific | 2025 |
| Aviadev Ltd | Transport & logistics | 2018 |
| Aviation Technologies Ltd | Professional & scientific | 2023 |
| AVJ Coaching and Consultancy Ltd | Health & social care | 2026 |
| Avocado Residential Limited | Real estate | 2021 |
| Avyay Aerial Manned Vehicle Development Ltd | Manufacturing | 2019 |
| Awaire Ltd | Information & communication | 2026 |
| Axion International Ltd | Professional & scientific | 2026 |
| Axtell Limited | Manufacturing | 2014 |
| Ayat Management Services Ltd | Financial services | 2024 |
| Ayna Real Estate Limited | Real estate | 2024 |
| Azizi Developments UK Ltd | Real estate | 2024 |
| Azure Ctech Ltd | Financial services | 2024 |
| B & D Clays Limited | Wholesale & retail | 2017 |
| B V a Roofing Limited | Construction | 2025 |
| B-Custom Ltd | Construction | 2021 |
| B. & D. Clays and Chemicals Limited | Wholesale & retail | 1974 |
| B.L. Vision Service (Farncombe) Limited | Wholesale & retail | 1965 |
| BAD BOY Lanyards Ltd | Manufacturing | 2021 |
| Baden Powell Court Management Company Limited | Households | 2004 |
| Bailey Building and Loan Limited | Real estate | 2024 |
| Bailey Investing Limited | Health & social care | 2021 |
| Bakehouse Mews Limited | Households | 2009 |