| Ashdown Clinic Limited | Health & social care | 1999 |
| Ashdown Lodge Care Home Limited | Health & social care | 2016 |
| Ashenden & Morrisroe Limited | Construction | 2011 |
| Ashenden Construction Limited | Construction | 1997 |
| Ashford & Sons Limited | Information & communication | 2014 |
| Ashley Properties UK Ltd | Real estate | 2007 |
| Ashty Limited | Real estate | 2021 |
| Ashure Waste Group Ltd | Water & waste | 2025 |
| Ashwood Lodge Management Company Limited | Households | 1987 |
| Ashwood Lodge Properties Limited | Real estate | 1997 |
| ASK Residential Properties Limited | Real estate | 2014 |
| Asma Investments Limited | Financial services | 2018 |
| ASN Trading Limited | Manufacturing | 2015 |
| Aspen Protect Limited | Administrative & support | 2023 |
| Aspen Rose Ltd | Administrative & support | 2021 |
| Asper Holdings Ltd | Real estate | 2019 |
| Asper Recruitment Ltd | Administrative & support | 2018 |
| Aspides Limited | Information & communication | 2023 |
| Assentum Limited | Real estate | 2017 |
| Asset Advisory & Management Ltd | Administrative & support | 2019 |
| Assets 1 Ltd | Real estate | 2020 |
| Assure Block Management Ltd | Real estate | 2018 |
| Assurity Advisory Ltd | Professional & scientific | 2026 |
| AST Inventory Ltd | Administrative & support | 2019 |
| Astuter Limited | Professional & scientific | 2019 |
| AT Legal Services Ltd | Professional & scientific | 2022 |
| AT Publishing Ltd | Information & communication | 2021 |
| AT Retail Ltd | Wholesale & retail | 2025 |
| Atavist Supplements Ltd | Wholesale & retail | 2020 |
| Atcon Consultants Limited | Professional & scientific | 2015 |
| Atelier 1 Limited | Professional & scientific | 1993 |
| Atelier Ciprian Zama Ltd | Construction | 2013 |
| ATG Furniture Ltd | Wholesale & retail | 2013 |
| Athans Dental Ltd | Health & social care | 2025 |
| Atina Caira Ltd | Administrative & support | 2018 |
| Atlantic International Movers Ltd | Professional & scientific | 2004 |
| Atlantis Industrial Ltd | Manufacturing | 2014 |
| Atlas Bookkeeping Limited | Professional & scientific | 2024 |
| Atomic Partnership Ltd | Arts & recreation | 1998 |
| ATS Development Solutions Limited | Administrative & support | 2015 |
| Attson Properties Limited | Real estate | 2017 |
| AU Conveyance Ltd | Transport & logistics | 2025 |
| Auchenkilns Park TL Ltd | Real estate | 2017 |
| Auckland Estates Limited | Real estate | 2019 |
| Aurora Properties (UK) Ltd | Real estate | 2012 |
| Aurora Properties Limited | Construction | 1995 |
| Aurora Revenue Collection Limited | Administrative & support | 2014 |
| Aurum Group Ltd | Construction | 2021 |
| Austintatious Limited | Manufacturing | 2017 |
| Autavia Transport Ltd | Transport & logistics | 2021 |
| Autism Spectrum Employment & Training Ltd | Education | 2026 |
| Autodelta (London) Limited | Wholesale & retail | 2010 |
| Autodelta Services Ltd | Wholesale & retail | 2026 |
| Autopilot Limited | Real estate | 1983 |
| Autostilo Restorations Limited | Wholesale & retail | 2018 |
| Autumn Breeze Developments Ltd | Real estate | 2019 |
| Autumn Breeze Group Ltd | Financial services | 2025 |
| Autumn Breeze Investments Limited | Real estate | 2017 |
| Autumn Money Ltd | Financial services | 2025 |
| Avakian Jewellery Limited | Administrative & support | 2011 |
| Avakian Limited | Administrative & support | 2011 |
| Avdc Design Limited | Professional & scientific | 2015 |
| Avia Advisory Limited | Administrative & support | 2018 |
| Aviana Media Limited | Arts & recreation | 2020 |
| Aviation Real Estate Limited | Real estate | 2023 |
| Avid Group Holdings Limited | Administrative & support | 2026 |
| Avid Networks Limited | Administrative & support | 2024 |
| Avid Overwatch Ltd | Administrative & support | 2025 |
| Avila Consultancy Limited | Professional & scientific | 1998 |
| Avivavisa Limited | Administrative & support | 2025 |
| Avrion Networks Limited | Information & communication | 2007 |
| AVT & Installation Limited | Construction | 2010 |
| Awoolfsson Osteopaths Ltd | Health & social care | 2002 |
| Awwecity Ltd | Information & communication | 2017 |
| AYG Group Limited | Administrative & support | 2023 |
| AZ Glass Ltd | Manufacturing | 2020 |
| Azhary Limited | Financial services | 2015 |
| Azhary Properties Ltd | Real estate | 2021 |
| Azhary Software Limited | Information & communication | 2016 |
| Azizi Cues Limited | Agriculture & fishing | 2015 |
| Azure Organisation Ltd | Administrative & support | 2021 |
| B & D Cleaning Services Limited | Administrative & support | 2013 |
| B & M Autocare Limited | Wholesale & retail | 2009 |
| B & P Freight Limited | Information & communication | 1997 |
| B & R Payroll Ltd | Professional & scientific | 2016 |
| B and M Partners Home Improvements Ltd | Construction | 2011 |
| B Wealth Services Limited | Financial services | 2014 |
| B-Jack Properties Ltd | Administrative & support | 2013 |
| B3 Kingston Ltd | Hospitality | 2025 |
| B4E Solutions Ltd | Construction | 2007 |
| Back to Front Vintage Ltd | Wholesale & retail | 2022 |
| Backlund Wellness Limited | Health & social care | 2006 |
| Bacon Ventures Ltd | Hospitality | 2025 |
| Bacrest Limited | Construction | 2008 |
| Baeche Limited | Hospitality | 2025 |
| Bagel Baby Ltd | Hospitality | 2020 |
| Bahweep (UK) Limited | Professional & scientific | 2009 |
| Bailey Campbell Limited | Other services | 2016 |
| Bakeebzlogistics Limited | Transport & logistics | 2016 |
| Bakers Dozen Studios Ltd | Other services | 2020 |