| Ashchurch House Limited | Health & social care | 1998 |
| Ashdene House Limited | Health & social care | 2000 |
| Ashfield Accountancy Ltd | Professional & scientific | 1993 |
| Ashfield Care Homes Limited | Health & social care | 1990 |
| Ashford House Limited | Health & social care | 1998 |
| Ashgables House Limited | Health & social care | 2006 |
| Ashgale House Limited | Health & social care | 2000 |
| Ashgate House Limited | Health & social care | 2000 |
| Ashglen House Limited | Health & social care | 2006 |
| Ashgold House Limited | Health & social care | 2000 |
| Ashingham House Limited | Health & social care | 2000 |
| Ashington House Limited | Health & social care | 1999 |
| Ashking House Limited | Health & social care | 2000 |
| Ashlane House Limited | Health & social care | 2001 |
| Ashlee Lodge Limited | Health & social care | 2001 |
| Ashley Homes Limited | Construction | 2005 |
| Ashley Irvin Limited | Administrative & support | 2013 |
| Ashley James Design Limited | Professional & scientific | 2023 |
| Ashley Services Garden Machinery Limited | Wholesale & retail | 2024 |
| Ashlong House Limited | Health & social care | 2000 |
| Ashmeadows House Limited | Health & social care | 2005 |
| Ashmount House Limited | Health & social care | 2006 |
| Ashpark House Limited | Health & social care | 1998 |
| Ashpoint House Limited | Health & social care | 2000 |
| Ashprime Properties Limited | Health & social care | 2010 |
| Ashriver House Limited | Health & social care | 2007 |
| Ashrose Plumbing and Heating Ltd | Construction | 2013 |
| Ashstone House Limited | Health & social care | 2001 |
| Ashtead House Limited | Health & social care | 1999 |
| Ashton Consulting Limited | Professional & scientific | 2000 |
| Ashurst House Limited | Health & social care | 2001 |
| Ashwest House Limited | Health & social care | 2001 |
| Ashwood Grange Residents Association Limited | Households | 1989 |
| Ashwood Grove Property Limited | Real estate | 2024 |
| Ashyew House Limited | Health & social care | 2000 |
| Asia Globe Inspection Services (Europe) Limited | Professional & scientific | 2012 |
| Asianjewellery Limited | Wholesale & retail | 2025 |
| ASK Advice Limited | Administrative & support | 2016 |
| Asknutrition Limited | Health & social care | 2002 |
| Aslfba Ltd | Wholesale & retail | 2025 |
| ASM Imperial Rugs Limited | Wholesale & retail | 2026 |
| ASN Services Limited | Information & communication | 2017 |
| Aspect Engineering London Limited | Manufacturing | 2017 |
| Aspect Roofing Services Limited | Construction | 2021 |
| Aspen Flooring Ltd | Wholesale & retail | 2008 |
| Aspen Marketing Group Limited | Professional & scientific | 2004 |
| Aspen Properties Limited | Financial services | 2018 |
| Aspen Wholesale Ltd | Wholesale & retail | 2026 |
| Aspire Architecture & Surveying Ltd | Professional & scientific | 2013 |
| ASQ Surrey Ltd | Real estate | 2021 |
| ASR Engineering Limited | Other services | 2009 |
| Asset Monetization Holdings Limited | Financial services | 2021 |
| Assist Eyecare Limited | Health & social care | 2015 |
| Association for Professional Executive Coaching & Supervision | Other services | 2005 |
| Assure Health Limited | Administrative & support | 2012 |
| AST Catering Ltd | Hospitality | 2025 |
| Aston Read Limited | Information & communication | 2005 |
| Astor Estates Limited | Real estate | 2014 |
| AT Collective Group Ltd | Wholesale & retail | 2026 |
| AT Quality Consultant Ltd | Professional & scientific | 2019 |
| AT Your Service Taxis Limited | Transport & logistics | 2014 |
| ATD Group Ltd | Construction | 2016 |
| Atelier Cars Woking Ltd | Transport & logistics | 2024 |
| Atelier Kisai Limited | Wholesale & retail | 2017 |
| ATG Entertainment Limited | Arts & recreation | 1991 |
| ATG London Limited | Arts & recreation | 2000 |
| ATG Productions Limited | Arts & recreation | 2014 |
| Atgp Shows Four Limited | Arts & recreation | 2022 |
| Atgp Shows One Limited | Arts & recreation | 2023 |
| Atgp Shows Three Limited | Arts & recreation | 2023 |
| Atgp Shows Two Limited | Arts & recreation | 2023 |
| Athena Accounting Consultancy Limited | Professional & scientific | 2024 |
| ATI SIP Trustees 1 Limited | Extraterritorial | 2015 |
| ATI SIP Trustees 2 Limited | Extraterritorial | 2015 |
| ATI UK Holdings Ltd | Financial services | 2021 |
| Atif Superstore Limited | Wholesale & retail | 2004 |
| Atiyah Enterprises Limited | Wholesale & retail | 2026 |
| Atkinson Greenfield Capital Limited | Real estate | 2025 |
| Atlantis Recruitment Ltd | Professional & scientific | 2025 |
| Atlas Bulk Carriers Limited | Wholesale & retail | 1989 |
| Atlas Rock Solutions Ltd | Information & communication | 2023 |
| Atmosflair Limited | Administrative & support | 2015 |
| Atom Universe Limited | Information & communication | 2014 |
| Atomic Trading Systems Limited | Information & communication | 2019 |
| Atoz Care Solutions Limited | Health & social care | 2025 |
| Atrium Air Conditioning Limited | Construction | 1994 |
| Atticus 7 Limited | Information & communication | 2012 |
| ATZ Sales and Lettings Ltd | Real estate | 2025 |
| Audio Design Limited | Wholesale & retail | 1995 |
| Aughtersons Limited | Professional & scientific | 2009 |
| Augmen Limited | Professional & scientific | 2021 |
| Augmynt Ltd | Health & social care | 2019 |
| Aukware Ltd | Wholesale & retail | 2021 |
| Aultone Limited | Construction | 1981 |
| AUM Enterprises Ltd | Wholesale & retail | 2024 |
| Auratecture Ltd | Information & communication | 2023 |
| Aurea LUX Limited | Real estate | 2025 |
| Aurevion Tech Limited | Wholesale & retail | 2026 |
| Auri Massage IL Limited | Other services | 2024 |
| Aurora Elite Group Ltd | Arts & recreation | 2026 |