| AMN Consulting Limited | Professional & scientific | 2015 |
| Ample Cooling Limited | Manufacturing | 2021 |
| Amrose Scaffolding Ltd | Construction | 2018 |
| Anderson King Limited | Financial services | 1998 |
| Andreou Investments Limited | Real estate | 2014 |
| Andreou Property Management Services Ltd | Real estate | 2025 |
| Andrew Mark Associates Limited | Professional & scientific | 2022 |
| Andy Robinson Fabrications Limited | Manufacturing | 2002 |
| Andy Turner Decorators Limited | Construction | 2012 |
| Angel Decors Limited | Construction | 2015 |
| Angel Sitters UK Ltd | Health & social care | 2025 |
| Angels Academy Nursery and PRE School Ltd | Health & social care | 2020 |
| Angels Construct Ltd. | Construction | 2016 |
| Angels Messanger Limited | Transport & logistics | 2024 |
| Angus Way Limited | Wholesale & retail | 2025 |
| Anna Malone Coaching Ltd | Information & communication | 2024 |
| Annuko Limited | Wholesale & retail | 2018 |
| Anscar Accounting Limited | Professional & scientific | 2007 |
| Anton James Limited | Wholesale & retail | 2011 |
| Appleby Estates Ltd | Real estate | 2017 |
| Approved Waste Services Limited | Water & waste | 2024 |
| Appthebusiness Ltd | Information & communication | 2017 |
| Appunwrapped Ltd | Information & communication | 2021 |
| Aqua Mech Ltd | Wholesale & retail | 2024 |
| Aquacreed Afro-Carribean Foods Ltd | Wholesale & retail | 2024 |
| Aquarius Pool Services Ltd | Administrative & support | 2015 |
| AR Powerbi Solutions Limited | Professional & scientific | 2025 |
| Archery Consulting Limited | Professional & scientific | 2020 |
| Ardsheal Partners Ltd | Professional & scientific | 2025 |
| Arenafit Limited | Arts & recreation | 2016 |
| Arkael Consulting Ltd | Professional & scientific | 2022 |
| Armstrong Plastering Ltd | Construction | 2025 |
| Arrow Line Marketing Limited | Professional & scientific | 2008 |
| Arshami Ltd | Health & social care | 2026 |
| Art Image Library Limited | Information & communication | 2013 |
| Arteco System Ltd | Information & communication | 2025 |
| Artimagelibrary.Com Limited | Arts & recreation | 2014 |
| Arvida Engineering Limited | Administrative & support | 1996 |
| AS Consultants for Business Limited | Professional & scientific | 2015 |
| AS Live Media Ltd | Information & communication | 2011 |
| Ascot Wholesale Limited | Wholesale & retail | 2005 |
| Ashcroft Construction Limited | Construction | 2018 |
| Ashleigh Court (Surbiton) Limited | Households | 1998 |
| Ashley Homes Berkshire Ltd | Construction | 2019 |
| Ashley Homes One Limited | Construction | 2019 |
| Ashurst Property Ltd | Real estate | 2024 |
| Ashwhistle Limited | Professional & scientific | 2018 |
| ASJ Capital Ventures Limited | Financial services | 2022 |
| ASJ Consulting Ltd | Information & communication | 2022 |
| ASK Tilly Ltd | Hospitality | 2024 |
| ASP Trade Ltd | Construction | 2020 |
| Aspern Gold Limited | Wholesale & retail | 2003 |
| Aspex Property Development Limited | Construction | 2003 |
| Aspire Leasing Limited | Financial services | 2009 |
| Assert Property Services Limited | Construction | 2012 |
| Aston Barclay Chelmsford Limited | Wholesale & retail | 1959 |
| Aston Barclay Holdings Group Limited | Wholesale & retail | 2017 |
| Aston Barclay Holdings Limited | Wholesale & retail | 2002 |
| Aston Barclay Leeds Limited | Wholesale & retail | 1991 |
| Aston Barclay Limited | Wholesale & retail | 1982 |
| Aston Barclay Prees Heath Limited | Wholesale & retail | 1989 |
| Aston Barclay Westbury Limited | Wholesale & retail | 1965 |
| Astran Aggregates Ltd | Transport & logistics | 2025 |
| Atkinson Science Limited | Professional & scientific | 2014 |
| ATM Parts Company Limited | Information & communication | 2019 |
| Atom Access Limited | Construction | 1997 |
| Augmentum Ltd | Other services | 2023 |
| Auricl Limited | Professional & scientific | 2015 |
| Aurora 360 Limited | Extraterritorial | 2011 |
| Austin Mango Limited | Financial services | 1995 |
| Auto Solutions (Sandhurst) Ltd | Wholesale & retail | 2013 |
| Autobody by Butler Ltd | Wholesale & retail | 2025 |
| Autolink Limited | Extraterritorial | 1995 |
| Automation Installations Limited | Professional & scientific | 2011 |
| Autonatic Limited | Wholesale & retail | 2003 |
| Autos on Show Limited | Extraterritorial | 2017 |
| Autotrade International Limited | Construction | 1981 |
| Autotrade Limited | Wholesale & retail | 2017 |
| Autotrax Limited | Professional & scientific | 1994 |
| Autumn Cottage Childcare Limited | Health & social care | 2022 |
| Aviation & Marine Interiors Limited | Transport & logistics | 1985 |
| Avocet Cyber Services Limited | Information & communication | 2024 |
| Avvanti Ltd | Real estate | 2020 |
| Axiom Data Ltd | Information & communication | 2020 |
| Ayres Real Estate Limited | Real estate | 2024 |
| Azorius Limited | Information & communication | 2020 |
| B & M Fencing Limited | Construction | 1972 |
| B & V Cars Limited | Wholesale & retail | 2020 |
| B M R Countryside Limited | Administrative & support | 2007 |
| B. Jamieson Golf Advisors Limited | Arts & recreation | 1995 |
| B.K. Property Limited | Real estate | 2015 |
| Baby Sensory South West Limited | Education | 2016 |
| Baked PR Ltd | Professional & scientific | 2024 |
| Balance & Bloom Wellness Ltd | Hospitality | 2025 |
| Balanced Kids Ltd | Health & social care | 2005 |
| Barker Case Management Limited | Health & social care | 2026 |
| Barley Brothers Events Ltd | Hospitality | 2025 |
| Barrett's Roofing Ltd | Construction | 2024 |
| Barron Land Solutions Ltd | Professional & scientific | 2025 |
| Barton Wheeler Limited | Real estate | 2024 |