| Ametrik Limited | Professional & scientific | 2004 |
| AMG North East Limited | Real estate | 1997 |
| AMG Projects Limited | Real estate | 2001 |
| AMI Services Limited | Real estate | 2005 |
| Amilforce Limited | | 1983 |
| Amish Ltd | Hospitality | 2007 |
| Amlogan Consulting Limited | Information & communication | 2006 |
| Ammacare Solutions Ltd | Health & social care | 2026 |
| Amos Butler Limited | Information & communication | 2002 |
| Ample Security Systems Limited | Administrative & support | 1999 |
| Ampurias Ventures Limited | Professional & scientific | 2018 |
| Amsu Limited | Information & communication | 2005 |
| Amtax Interactive Solutions Limited | Professional & scientific | 1995 |
| ANA Zenic Design Ltd | Wholesale & retail | 2003 |
| Anaesthetic Associates Limited | Health & social care | 2001 |
| Analytical Decisions Limited | Professional & scientific | 2001 |
| Analytical Simulation Consultancy Limited | Professional & scientific | 1996 |
| Anan Limited | Wholesale & retail | 1996 |
| Anavo Care (Hailsham) Limited | Health & social care | 2025 |
| Anavo Care II Ltd | Financial services | 2025 |
| Anavo Care OHF Limited | Financial services | 2025 |
| Andalucia.Com Limited | Information & communication | 2001 |
| Andarta Advisory Ltd | Professional & scientific | 2024 |
| Andion IT Limited | Information & communication | 2004 |
| Ando Stores Limited | Wholesale & retail | 2006 |
| Andre Films Ltd | Extraterritorial | 2016 |
| Andrea Storey Designs Ltd | Professional & scientific | 2003 |
| Andrew F WYE Limited | Professional & scientific | 2005 |
| Andrew Goddon Limited | Professional & scientific | 2007 |
| Andy's Barbers Limited | Other services | 2003 |
| Andy's Rigging Ltd | Information & communication | 2020 |
| Angel Plastics Limited | Administrative & support | 2007 |
| Angel Ramblings Limited | Extraterritorial | 2005 |
| Anglechange Limited | Professional & scientific | 1987 |
| Anglers Residents Company Limited(The) | Households | 1966 |
| Anglian Service Team Limited | Administrative & support | 1999 |
| Anglo Foreign Affairs Limited | Professional & scientific | 1993 |
| Anglo Sound & Vision Limited | Wholesale & retail | 1998 |
| Anglo-Dutch Engineering Company Limited | Wholesale & retail | 1965 |
| Animal Tracks Productions Limited | Information & communication | 1985 |
| Anjash Limited | Real estate | 2006 |
| ANM Home Solutions Limited | Construction | 2018 |
| Anmi Properties Limited | Real estate | 2010 |
| Annabray Limited | Extraterritorial | 1990 |
| Anne Lloyd Consultants | | 1986 |
| Anngar Limited | Professional & scientific | 2007 |
| Anoils Ltd | Construction | 2017 |
| Anoils Properties Limited | Real estate | 2019 |
| ANR UK Ltd | Wholesale & retail | 2026 |
| Ansam Autocentre Limited | Wholesale & retail | 2001 |
| Anshel Limited | Wholesale & retail | 2005 |
| Antaris Technology Limited | Information & communication | 1997 |
| Anthony Alexandra Associates Limited | Administrative & support | 2013 |
| Anthony Petroleum Co Limited | Wholesale & retail | 2005 |
| Anthony Rose Limited | Information & communication | 1996 |
| Antique Buildings Limited | Professional & scientific | 1983 |
| Anton's Limited | Wholesale & retail | 2002 |
| Antron Care Limited | Construction | 1991 |
| Antwi Associates Limited | Information & communication | 2005 |
| Anycom Ltd | Wholesale & retail | 2002 |
| Aoife B Ltd | Hospitality | 2013 |
| AP Technical Consultancy Limited | Information & communication | 2015 |
| Aparajita Limited | Information & communication | 2005 |
| Apex Brickcutters Limited | Manufacturing | 2003 |
| Apex Global Services Limited | Professional & scientific | 1998 |
| Apex Heating Co. Limited(The) | Wholesale & retail | 1982 |
| Apex Medical Ultrasound Ltd | Health & social care | 2023 |
| Apollo Business Research Limited | Professional & scientific | 2001 |
| Apollo Designer Ltd | Information & communication | 2020 |
| Apollo Event Consultants Ltd | Arts & recreation | 2002 |
| Appendown Limited | | 1979 |
| Applebee Property LLP | | 2026 |
| Applicity Limited | Information & communication | 2007 |
| Applied Energy Limited | Professional & scientific | 1996 |
| Apricoto Limited | Wholesale & retail | 2006 |
| April Close Residents Limited | Households | 1992 |
| APX Associates Limited | Hospitality | 1995 |
| Aqua BDS Limited | Health & social care | 2010 |
| Aqua Paradiso Limited | Construction | 1999 |
| Aquanaut Scuba and Snorkelling Centre Limited | Wholesale & retail | 2007 |
| Aquatech Water Treatment Products and Services Ltd | Water & waste | 2002 |
| Aqueous Logic Limited | Manufacturing | 1995 |
| AR Concepts Limited | Professional & scientific | 1998 |
| AR Consulting Group Limited | Administrative & support | 2005 |
| AR Consulting Limited | Professional & scientific | 1996 |
| Arabella Health Staffing Limited | Administrative & support | 2005 |
| Arabica Services Limited | Administrative & support | 2002 |
| Aralia House Management Limited | Households | 1989 |
| Aran Home Ltd | Real estate | 1999 |
| Arana Properties Limited | Real estate | 2022 |
| Arbor Consulting Limited | Professional & scientific | 1998 |
| Archcomp Limited | Information & communication | 1998 |
| Archiserve Design Limited | Professional & scientific | 2001 |
| Architectural Design and Surveying Ltd | Professional & scientific | 2020 |
| Archway Motors Limited | Wholesale & retail | 2006 |
| Ardvale Properties Limited | Construction | 1972 |
| Areaview (Southern) Limited | Extraterritorial | 2004 |
| Arem Investments Limited | Real estate | 1999 |
| Argentine Northern Finance Company Limited | Professional & scientific | 1908 |
| Arikaa PVT Ltd | Health & social care | 2023 |