| Andrew John Charles Ltd | Construction | 2025 |
| Andrew Stilton Limited | Professional & scientific | 2014 |
| Andrew Tart Motor Engineering Ltd | Wholesale & retail | 2011 |
| Andrews Asset Holdings Ltd | Real estate | 2024 |
| Andrews Laboratory Services Limited | Other services | 2006 |
| Andy Loos Holdings Limited | Financial services | 2021 |
| Andy Loos Limited | Other services | 1997 |
| Andy MAW Design Ltd | Information & communication | 2021 |
| Andy Oakes CNC Services Limited | Manufacturing | 2011 |
| Andy's Property Services Limited | Construction | 2017 |
| Angel Bank Garage Limited | Wholesale & retail | 2014 |
| Anglesey Bait Company Limited | Extraterritorial | 2005 |
| Angus Hoare Golf Ltd | Wholesale & retail | 2016 |
| Anriesin Ltd | Administrative & support | 2024 |
| ANS Transportation Ltd | Other services | 2020 |
| Ansaai Ltd | Hospitality | 2025 |
| Ansfied Ltd | Administrative & support | 2021 |
| Anti Slip Solutions Limited | Wholesale & retail | 2006 |
| Anypoint Services Ltd | Administrative & support | 2026 |
| Anzbiuer Ltd | Health & social care | 2024 |
| Apex & Aura Limited | Professional & scientific | 2026 |
| Apex SOX Ltd | Wholesale & retail | 2021 |
| APG Cargo Limited | Transport & logistics | 2004 |
| APG Limited | Extraterritorial | 1986 |
| APG Travel Limited | Administrative & support | 1996 |
| APG UK Limited | Administrative & support | 1998 |
| Aphex Holdings Limited | Financial services | 2019 |
| Aphex Warehouse Services Ltd | Construction | 2015 |
| Apna Punjab Farm Ltd | Agriculture & fishing | 2025 |
| Apollo & Luna Properties Ltd | Hospitality | 2026 |
| Apollo Marble & Granite Limited | Manufacturing | 2023 |
| Appyepos Limited | Administrative & support | 2022 |
| APS Medcare Ltd | Health & social care | 2026 |
| Apse Building Design Limited | Professional & scientific | 2015 |
| Apstorm Ltd | Information & communication | 2020 |
| APT Chemicals International Limited | Wholesale & retail | 2006 |
| APT Ingredients Ltd | Professional & scientific | 2025 |
| Apunte Alto Limited | Administrative & support | 2008 |
| APW Electrical Solutions Ltd | Construction | 2019 |
| Aqua 7 Limited | Real estate | 2021 |
| Aqua Telecom Midlands Ltd | Information & communication | 2014 |
| Aqua Water Systems Limited | Manufacturing | 1985 |
| Aquatic Wholesale Limited | Wholesale & retail | 2023 |
| ARA Construction Ltd | Construction | 2025 |
| Arachsys Internet Services Limited | Information & communication | 1998 |
| Arch Hill Residential Catering Ltd | Hospitality | 2020 |
| Archers Stores Ltd | Wholesale & retail | 2002 |
| Arctic Spas Ltd | Wholesale & retail | 2000 |
| Arden Consultancy Limited | Professional & scientific | 2024 |
| Ardisiart Ltd | Transport & logistics | 2022 |
| Areley Mews Management Company Limited | Households | 2002 |
| Arenarian Ltd | Transport & logistics | 2022 |
| Arlington Jones Limited | Financial services | 2025 |
| ARM Facilities LLP | | 2016 |
| ARM Windows and Doors Solutions Limited | Construction | 2025 |
| Arnaya Ltd | Information & communication | 2019 |
| Arnaya Property Ltd | Real estate | 2025 |
| Arnicarita Ltd | Administrative & support | 2020 |
| Arquette Holdings Limited | Real estate | 2021 |
| Arteng Limited | Manufacturing | 2022 |
| Artisan Construction Group Ltd | Construction | 2025 |
| Artspocket Ltd | Transport & logistics | 2019 |
| AS Geotrans Ltd | Transport & logistics | 2016 |
| Asbestos Environmental Surveyors Ltd | Professional & scientific | 2022 |
| Asbestos to Go (Services) Ltd | Water & waste | 2014 |
| Ashford Civil Engineering Ltd | Real estate | 2014 |
| Ashley Construction Limited | Construction | 2011 |
| Ashley Jones Consultancy Limited | Information & communication | 2020 |
| Ashleys Bakery Limited | Manufacturing | 2025 |
| Ashrab Ltd | Wholesale & retail | 2022 |
| Askgg Limited | Financial services | 2022 |
| ASL Ventures Ltd | Financial services | 2022 |
| Aspect Real Estate Ltd | Real estate | 2025 |
| Asromiux Ltd | Transport & logistics | 2023 |
| Associated Container Parts Ltd | Wholesale & retail | 2014 |
| Assured Installations Ltd | Construction | 2016 |
| Aston Sandford Ltd | Administrative & support | 2021 |
| Astoria Studio Ltd | Information & communication | 2023 |
| Asvorzium Ltd | Transport & logistics | 2023 |
| Atek Properties Ltd | Real estate | 2022 |
| Athena Building Contractors Limited | Construction | 2007 |
| Atkinson Chittick Limited | Professional & scientific | 2014 |
| ATL Recruitment Limited | Administrative & support | 2024 |
| Attain Auditing Limited | Professional & scientific | 2024 |
| Auchtertool Ltd | Transport & logistics | 2021 |
| Augusta Taurinorum Ltd | Administrative & support | 2022 |
| Augustus D Ltd | Real estate | 2009 |
| Auresa Accounting Limited | Professional & scientific | 2018 |
| Austyn Associates Limited | Professional & scientific | 2018 |
| Authentic Thai Massage Lounge Limited | Health & social care | 2024 |
| Autism Inclusion CIC | Education | 2012 |
| Auto Euro Trading Limited | Wholesale & retail | 2021 |
| Auto Solutions (GB) Limited | Wholesale & retail | 2006 |
| Auto Vehicle Specialists Limited | Wholesale & retail | 2003 |
| Automek Ltd | Wholesale & retail | 2019 |
| Autoweld Motor Services Limited | Wholesale & retail | 2017 |
| Auxilium Academy Group Ltd | Information & communication | 2025 |
| AV Carr Ltd | Transport & logistics | 2021 |
| AV Kane Ltd | Transport & logistics | 2021 |
| Avatar Bowling Limited | Hospitality | 2018 |