| Absorbio Ltd | Other services | 2023 |
| Abta 1 Limited | Administrative & support | 1989 |
| AC Engineering (Byfleet) Limited | Manufacturing | 2003 |
| AC Limo & Commercial Services Limited | Transport & logistics | 2002 |
| Academy Cleaning & Maintenance Limited | Administrative & support | 1997 |
| Acas Limited | Real estate | 1997 |
| Accent Film and Television Limited | Information & communication | 2003 |
| Access Support Services Limited | Administrative & support | 2003 |
| Accomco Limited | Real estate | 2006 |
| Accomsta Limited | Real estate | 2024 |
| Account on Time Limited | Financial services | 2014 |
| Accountancy First Limited | Professional & scientific | 1999 |
| Accountancy Team Limited | Professional & scientific | 2002 |
| Accounting Uncorked Ltd | Professional & scientific | 2006 |
| Accountingability Limited | Professional & scientific | 2008 |
| Accountingtax.Co.Uk Ltd | Real estate | 2002 |
| Accounts Completion Limited | Professional & scientific | 2002 |
| Accubizz Ltd | Information & communication | 1994 |
| Acegraphics Limited | | 1993 |
| Acetek Electrical Limited | Manufacturing | 2001 |
| Acipp HR & Bureau Payroll Ltd | Professional & scientific | 2023 |
| Acme Systems Ltd | Information & communication | 2003 |
| ACN Trading Limited | Wholesale & retail | 1997 |
| Acool Limited | Administrative & support | 2004 |
| Acorn Legacy Investments Ltd | Real estate | 2024 |
| Acornstone Limited | Financial services | 1998 |
| Acoustic Ceilings UK Ltd | Construction | 2004 |
| Acrecrown Corporation Ltd | Real estate | 2000 |
| ACT Cleaning Services Limited | Administrative & support | 2003 |
| Act&T Limited | Professional & scientific | 2006 |
| Actaeon Information Systems Ltd | Information & communication | 1998 |
| Actionpoint Solutions Limited | Information & communication | 1999 |
| Active Connect Ltd | Construction | 2002 |
| Active Link Limited | Information & communication | 1998 |
| Actual Electrical Limited | Construction | 2007 |
| Actuarial Solutions Limited | Information & communication | 1995 |
| Acumen Professional Services Limited | Professional & scientific | 2004 |
| Acupuncture Therapy Centre Limited | Health & social care | 2013 |
| AD Car Care Farnham Ltd | Other services | 2016 |
| AD Communications Trustees Ltd | Professional & scientific | 2024 |
| AD Design Associates Limited | Professional & scientific | 2005 |
| ADA Inmates Ltd | Information & communication | 2023 |
| Adams,May & Co.Limited | Real estate | 1954 |
| Adapt Retail Limited | Wholesale & retail | 2025 |
| Adaptus Ltd | Professional & scientific | 2002 |
| Adastral Garages Limited | | 1965 |
| Adayaalam | Professional & scientific | 2016 |
| Addiction Support and Care Agency (Asca) | Health & social care | 1994 |
| Addilon Limited | | 1983 |
| Adec Marine Limited | Manufacturing | 1984 |
| Adem Hair Design Limited | Other services | 2013 |
| ADF Developers Limited | Extraterritorial | 2019 |
| Adfield Limited | Other services | 2020 |
| ADH Management Services Limited | Professional & scientific | 2003 |
| Admiral Telecom Limited | Information & communication | 2006 |
| Adnitt Acoustic Trustees Limited | Professional & scientific | 2021 |
| Adnor Ltd. | Professional & scientific | 1965 |
| Adorn Jewellers Limited | Wholesale & retail | 2000 |
| Adstic (U.K.) Limited | Information & communication | 1992 |
| Advance Fabrication & Installat Ions Ltd | | 1981 |
| Advanced 2000 Limited | Construction | 1994 |
| Advanced Generics Limited | Other services | 2003 |
| Advanced Information Management Solutions Limited | Information & communication | 1996 |
| Advanced Minerals Limited | Manufacturing | 1990 |
| Advanced Technology Marketing Services Limited | Wholesale & retail | 2003 |
| Advancestart Property Management Limited | Households | 1992 |
| Adventure Leisure Limited | Arts & recreation | 1984 |
| Adventurean Ltd | Professional & scientific | 2000 |
| Advirt.Com Limited | Information & communication | 2008 |
| ADW Consulting Limited | Information & communication | 2003 |
| Adwest Holdings Limited | | 1991 |
| Aegan Real Estates Limited | Real estate | 2021 |
| Aequus Limited | Administrative & support | 2000 |
| Aeroservice UK Limited | Wholesale & retail | 2005 |
| Aerospace Developments (London) Limited | | 1977 |
| AF Beauty Kingston Ltd | Other services | 2016 |
| Afay Limited | Real estate | 1999 |
| AFL Group Limited | Professional & scientific | 2006 |
| Aftermarket Logistic Services Ltd | Professional & scientific | 2004 |
| Agara Ltd. | Real estate | 2020 |
| AGE UK Merton | Other services | 2004 |
| Agenda Trading Limited | Wholesale & retail | 2002 |
| Agilify Consulting Limited | Information & communication | 2024 |
| AGM Landscaping Limited | Administrative & support | 2016 |
| Agricultural & Groundscare Credit Limited | Financial services | 2006 |
| AGS Transportuk Ltd | Transport & logistics | 2017 |
| Agshathai Express Company Limited | Hospitality | 2023 |
| AGW RTM Company Limited | Real estate | 2015 |
| AH Commissioning Services Limited | Professional & scientific | 2007 |
| AH HA Software Limited | Information & communication | 2003 |
| Ahdem Ltd | Wholesale & retail | 2022 |
| AHG Investment Limited | Wholesale & retail | 2018 |
| AI and Code Consultants Limited | Information & communication | 2020 |
| AID to the Church in Need (United Kingdom) | Other services | 2003 |
| Air-Bilal Ltd | Professional & scientific | 2016 |
| Airbag MAN Limited | Extraterritorial | 2004 |
| Aircon Hire Limited | Administrative & support | 2001 |
| Aireville Investments Ltd. | Real estate | 1967 |
| Airplayer Ltd | Arts & recreation | 2006 |
| Airsphere Limited | Professional & scientific | 2017 |