| Animal Dynamics Limited | Professional & scientific | 2015 |
| Anna Louise Aesthetics Ltd | Other services | 2024 |
| Annabanana Limited | Professional & scientific | 2020 |
| Anthology Partners Ltd | Information & communication | 2007 |
| Anthony Associates Limited | Professional & scientific | 2011 |
| Antony Cribb Ltd. | Administrative & support | 2014 |
| Anvil Dental Laboratory Ltd | Health & social care | 2017 |
| AOG Assist Ltd | Transport & logistics | 2024 |
| Aonc Limited | Other services | 2014 |
| AP Tours Ltd | Administrative & support | 2021 |
| Apex Business Solutions Ltd | Professional & scientific | 2023 |
| Apex Telecom Ltd | Information & communication | 2019 |
| Apiafi Associates Limited | Administrative & support | 2009 |
| Apollo Actuarial Ltd | Professional & scientific | 2023 |
| Apollo Submarine Cable System Limited | Information & communication | 2004 |
| Apple Print & Creative Holdings Limited | Manufacturing | 2014 |
| Apple Print and Creative Limited | Extraterritorial | 2013 |
| Apple Print Holdings Limited | Manufacturing | 2008 |
| Apple Print Limited | Manufacturing | 1986 |
| Applied Consumer Neuroscience Labs Ltd. | Professional & scientific | 2016 |
| April’S Baker Limited | Manufacturing | 2019 |
| Aqua Moving Services LLP | | 2009 |
| Aqualoc Limited | Administrative & support | 1999 |
| Aquila Construction Limited | Construction | 2011 |
| AR Car Cleaning Ltd | Administrative & support | 2020 |
| AR PM Consulting Limited | Information & communication | 2015 |
| Aramoor Limited | Financial services | 2025 |
| ARB Assets Limited | Administrative & support | 2013 |
| Arborite Tree Services Limited | Agriculture & fishing | 2008 |
| Arbris Limited | Real estate | 2019 |
| ARC Windows Limited | Construction | 2024 |
| Arc-Hq Ltd | Real estate | 2011 |
| Arcady Consultancy Limited | Administrative & support | 2007 |
| Arcanus Limited | Information & communication | 2025 |
| Arch Partnership UK Limited | Information & communication | 2022 |
| Archseeker Ltd | Real estate | 2022 |
| Area Sweep Limited | Administrative & support | 2017 |
| Arelcome Advisory Limited | Information & communication | 2017 |
| Arena Travel Limited | Transport & logistics | 1992 |
| Argo Transport Ltd | Transport & logistics | 2013 |
| Argonaut Solutions Ltd | Professional & scientific | 2009 |
| Aria 51 (Property Holdings) Ltd | Real estate | 2020 |
| Ariane Education Ltd | Education | 2021 |
| Ariel Biblical Studies UK Ltd | Other services | 2025 |
| Arisedata Infotech Ltd | Information & communication | 2020 |
| ARK Architects Limited | Professional & scientific | 2012 |
| ARK Biosciences Ltd | Professional & scientific | 2025 |
| ARK Exports Ltd | Professional & scientific | 2022 |
| Arkero Ltd | Financial services | 2025 |
| Arkev Developments Ltd | Construction | 2025 |
| Aroy Consultancy Limited | Real estate | 2025 |
| Arra Design Consultants Limited | Professional & scientific | 2014 |
| Arrow (Newbury) Ltd | Wholesale & retail | 1995 |
| Arrow Limited | Wholesale & retail | 2008 |
| Art Lana Publishing Ltd | Information & communication | 2016 |
| Artemis Pro Ltd | Information & communication | 2024 |
| Artemis X Solutions Limited | Professional & scientific | 2024 |
| Artifax the Picture Framers Ltd | Wholesale & retail | 2009 |
| Artknit Studios London Limited | Wholesale & retail | 2025 |
| Aruch Ltd | Professional & scientific | 2017 |
| AS (Tapes) Limited | Professional & scientific | 2009 |
| As&Ist Limited | Other services | 2025 |
| Asap Auto Services Limited | Wholesale & retail | 2022 |
| Ascarlethaze Limited | Wholesale & retail | 2025 |
| Ascend Care Limited | Wholesale & retail | 2018 |
| Ascending Growth Limited | Professional & scientific | 2022 |
| Ascensia Diabetes Care UK Limited | Administrative & support | 2015 |
| Ascentae Limited | Other services | 2016 |
| Aseko Ltd | Wholesale & retail | 2019 |
| ASH Management Associates Ltd | Information & communication | 2011 |
| Ashbag Investments Ltd | Financial services | 2025 |
| Ashlie Brombley Ltd | Information & communication | 2019 |
| Ashmine Ltd | Wholesale & retail | 2013 |
| Ashmore Services (Newbury) Limited | Construction | 2001 |
| Asia Leaf Services Ltd | Wholesale & retail | 2004 |
| Asil Investments Limited | Administrative & support | 2018 |
| Asil Properties Limited | Real estate | 2025 |
| Askr Enterprises Ltd | Information & communication | 2024 |
| Aspire Equine Limited | Agriculture & fishing | 2022 |
| Assynia Limited | Extraterritorial | 2001 |
| Asterisq AI Limited | Professional & scientific | 2022 |
| Asteroid Pictures Ltd | Information & communication | 2022 |
| Astor Films Ltd | Information & communication | 2022 |
| AT Property Investment Limited | Real estate | 2005 |
| Athens Technology Partners Limited | Administrative & support | 2002 |
| Atif Khan Consultants Limited | Information & communication | 2009 |
| Atkins and Potts Limited | Manufacturing | 2004 |
| Atlantic View Limited | Real estate | 2024 |
| Atlantis Children's Books Limited | Information & communication | 2011 |
| Atlas Employment Ltd | Administrative & support | 2013 |
| ATR Solutions Ltd | Construction | 2020 |
| Auchterlonie Consulting Limited | Professional & scientific | 2015 |
| Audax Atelier Ltd | Wholesale & retail | 2025 |
| Audet Magna Ltd | Professional & scientific | 2018 |
| August Property Investment Ltd | Real estate | 2023 |
| August Third Holdings Limited | Financial services | 2023 |
| Aulë Ltd | Information & communication | 2020 |
| Auriga (Europe) Limited | Extraterritorial | 2016 |
| Austin-Reason Limited | Other services | 2016 |
| Auto Lane Garages Ltd | Wholesale & retail | 2014 |