| Andre LE LEU Physiotherapy Limited | Health & social care | 2015 |
| Andrea & Weil Property Company Ltd | Real estate | 2023 |
| Andrew Boothby Planning Consultant Ltd | Professional & scientific | 2026 |
| Andrew Damonte Design Limited | Professional & scientific | 2015 |
| Andrew Hacker Limited | Information & communication | 2013 |
| Andrew Hextall Limited | Health & social care | 2003 |
| Andrew R Currie Ltd | Professional & scientific | 2018 |
| Andrew Robert LEE Limited | Professional & scientific | 2017 |
| Andrews Martin & Co. Limited | Real estate | 1994 |
| Andy Mattin Consulting Ltd | Professional & scientific | 2019 |
| Angel Hands Ltd | Health & social care | 2010 |
| Angel of Education Limited | Education | 2019 |
| Angela Williams, Consulting, Advisory and Interim Services Limited | Administrative & support | 2016 |
| Angelina Filippone Ltd | Professional & scientific | 2024 |
| Angels DEN Funding Limited | Administrative & support | 2013 |
| Angiepam Care Ltd | Health & social care | 2022 |
| Anglo Asia Education Limited | Education | 2026 |
| Anglo Overseas Developments Limited | Real estate | 1995 |
| ANI Homes Ltd | Real estate | 2021 |
| Animalism Limited | Professional & scientific | 2013 |
| Aniseed Twist Limited | Information & communication | 2023 |
| Ankaa Auxivo LLP | | 2023 |
| Anna Korving Limited | Professional & scientific | 2016 |
| Annables by Davis Limited | Construction | 2026 |
| Anne-Marie Consulting Limited | Professional & scientific | 2007 |
| Annek Limited | Construction | 2018 |
| Announcement Productions Ltd | Arts & recreation | 2011 |
| Another String Properties Ltd | Real estate | 2025 |
| Anslow-Ryan Ltd | Administrative & support | 2023 |
| Ansonby Group Ltd | Financial services | 2023 |
| Anta Properties Ltd | Real estate | 2020 |
| Anterior Developments Limited | Construction | 2010 |
| Anterior Homes Limited | Construction | 2010 |
| Anthony Reynolds Gallery Limited | Wholesale & retail | 1991 |
| Anthropos Digital Care Limited | Information & communication | 2016 |
| Anticg I GP Limited | Financial services | 2021 |
| Anticg I LP | | 2022 |
| Anticg I Second GP LLP | | 2022 |
| Antler Home Developments Limited | Construction | 2024 |
| Antobeta Limited | Transport & logistics | 2019 |
| Anugraha Homes Limited | Hospitality | 2018 |
| Anyhome Limited | Real estate | 1986 |
| Anything Pet Limited | Information & communication | 2024 |
| Anything YOU CAN DO Limited | Wholesale & retail | 2015 |
| AO Consulting Europe Limited | Other services | 2017 |
| AOC Franchising Ltd | Administrative & support | 2025 |
| AON Projects Limited | Information & communication | 2019 |
| AOS Productions Limited | Arts & recreation | 2020 |
| AP SD Sixty Five Limited | Wholesale & retail | 2025 |
| Apache Associates Limited | Administrative & support | 2009 |
| APC Labs Ltd | Wholesale & retail | 2023 |
| Aperta Invest Ltd | Households | 2020 |
| Aperture Laboratories Ltd | Professional & scientific | 2019 |
| Apex Consulting Ltd | Professional & scientific | 2016 |
| Apex Support Services Limited | Real estate | 1997 |
| Apgar Games Ltd | Information & communication | 2024 |
| Aphelion Software Limited | Information & communication | 2007 |
| Aphex Heating Engineers Ltd | Construction | 2020 |
| Aplek Limited | Professional & scientific | 2020 |
| Apola Express Ltd | Information & communication | 2001 |
| Apollo Insolvency Limited | Other services | 2015 |
| Apollo Janitorial Supplies Limited | Wholesale & retail | 1977 |
| Apollo Leisure Sports Supplies Limited | Wholesale & retail | 1998 |
| App Tech Productions Limited | Wholesale & retail | 2021 |
| Appache Ltd | Information & communication | 2025 |
| Apple Taxis Limited | Transport & logistics | 2024 |
| Appletrees Childcare Limited | Professional & scientific | 2009 |
| Apptimized Limited | Information & communication | 2016 |
| Apptimized Software Limited | Information & communication | 2010 |
| Apption Ltd | Information & communication | 2024 |
| Apricity Financial Planning Ltd | Financial services | 2022 |
| Aprit Foods Ltd | Professional & scientific | 2022 |
| Aprit WFL Consulting Limited | Professional & scientific | 2025 |
| Aqua Co Properties Limited | Real estate | 2015 |
| Aqua District Ltd | Administrative & support | 2025 |
| Aqua-Tox Ltd | Health & social care | 2022 |
| Aquarius Computer Supplies Ltd | Wholesale & retail | 2007 |
| Aquila Grove Management Limited | Households | 2020 |
| Aquilas Ltd | Administrative & support | 2003 |
| Aqwa Management Ltd | Professional & scientific | 2025 |
| AR & AM Ltd | Manufacturing | 2025 |
| AR Car Specialist Limited | Wholesale & retail | 2025 |
| AR Smart Services Ltd | Wholesale & retail | 2025 |
| ARA Capital Partners Limited | Professional & scientific | 2021 |
| Arabic Gems Ltd | Education | 2023 |
| Arbitraze Ltd | Wholesale & retail | 2026 |
| Arborel (Holding) Limited | Administrative & support | 2009 |
| ARC Business Consulting Services Limited | Administrative & support | 2019 |
| ARC Pharma (UK) Limited | Professional & scientific | 2013 |
| Arcade Associates Limited | Other services | 1997 |
| Arch Shoreditch Ltd | Other services | 2018 |
| Archangel AI Ltd | Administrative & support | 2026 |
| Archer Maintenance Limited | Administrative & support | 2022 |
| Archers Enterprise Ltd | Professional & scientific | 2025 |
| Archetypal Apothecary Ltd | Administrative & support | 2023 |
| Archibuild Ltd | Construction | 2017 |
| Architechlabz Ltd | Information & communication | 2026 |
| Architectural Intelligence Limited | Extraterritorial | 2016 |
| Archway Technology Partners Ltd | Administrative & support | 2026 |
| Arcn Designs Ltd | Manufacturing | 2017 |