| Alazen Ltd | Information & communication | 2012 |
| Albert Street (Fleet) Management Company Limited | Households | 2018 |
| Alchemy Consulting Group Limited | Professional & scientific | 2017 |
| Alchemy Property Solutions Limited | Real estate | 2013 |
| Alder Quarter Freehold Management Limited | Households | 2018 |
| Alexandra FOX Brokers Limited | Financial services | 2020 |
| Alexandra FOX Ltd | Professional & scientific | 2016 |
| Alfkub Logistics Limited | Transport & logistics | 2026 |
| Alison Collins Cars Ltd | Wholesale & retail | 2025 |
| Alison Sutton Consulting Ltd | Professional & scientific | 2015 |
| Alive Juice Limited | Manufacturing | 2024 |
| Alizarin Partnership Ltd | Administrative & support | 2018 |
| ALL Areas Hire Services Ltd | Administrative & support | 2004 |
| ALL BS Ltd | Transport & logistics | 2018 |
| ALL Solutions Group UK Ltd | Administrative & support | 2021 |
| ALL TOO Human Ltd | Professional & scientific | 2023 |
| Alliance Infrastructure Group Limited | Financial services | 2026 |
| Alpha Consultancy Limited | | 1991 |
| Alpha Electrical Contracting Ltd | Construction | 2017 |
| Alpine Property Portfolio Limited | Administrative & support | 2016 |
| Alternotion Consulting Ltd | Other services | 2007 |
| ALTF3 Ltd | Information & communication | 2019 |
| Altham Aviation Ltd | Professional & scientific | 2016 |
| AM Accountancy Ltd | Professional & scientific | 2023 |
| Amberwood Associates Limited | Professional & scientific | 2005 |
| Amcams Ltd | Professional & scientific | 2024 |
| Amco Housing Ltd | Real estate | 2014 |
| Amelia Creations Limited | Construction | 2024 |
| Amerrall Limited | Professional & scientific | 1998 |
| Amici Cafe (Fleet) Limited | Hospitality | 2017 |
| Amoha Consulting Limited | Information & communication | 2013 |
| Amolyn Ltd | Professional & scientific | 2007 |
| Amprop Limited | Construction | 1996 |
| Amso Data Solutions Limited | Information & communication | 2013 |
| Amzing Software Solutions Ltd | Information & communication | 2017 |
| AN EYE for Detail Limited | Construction | 2018 |
| Anaid Construction Ltd | Construction | 2023 |
| Anbrett Group Ltd | Financial services | 2025 |
| Ancells Park Management Company Limited | Real estate | 1987 |
| Anees Iqbal Co Limited | Wholesale & retail | 2024 |
| Angel Nails and Beauty Ltd | Other services | 2023 |
| Angshu Ltd | Real estate | 2024 |
| Animal Behaviour Consult Ltd | Other services | 2015 |
| Animotion-Academy Limited | Education | 2025 |
| Anite Limited | Professional & scientific | 1984 |
| Ankora Ltd | Construction | 2017 |
| Anteroom Limited | Professional & scientific | 2026 |
| Anthoria Ltd. | Professional & scientific | 2013 |
| Anville Sensors Ltd | Manufacturing | 2001 |
| Aperio Consultancy Ltd | Information & communication | 2025 |
| Apgp Ltd | Administrative & support | 2022 |
| Apollo Mental Health and Well-Being CIC | Extraterritorial | 2024 |
| Application Performance Ltd | Information & communication | 2004 |
| Aquaflame Plumbing Contractors Ltd | Construction | 2023 |
| Aqualogix Technology Limited | Information & communication | 2019 |
| Aquilaris Ltd | Wholesale & retail | 2026 |
| Aras Marketing Ltd | Information & communication | 2017 |
| Archetypal Limited | Manufacturing | 2022 |
| Ardent Automotive Engineering Ltd | Wholesale & retail | 2021 |
| Arena Bingo Ltd | Arts & recreation | 2018 |
| Aristotle Solutions Limited | Professional & scientific | 2008 |
| Armstrong House (Farnborough) Residents Management Company Limited | Households | 2015 |
| Armstrong Property 2023 Ltd | Real estate | 2023 |
| Aromacare Ltd | Extraterritorial | 2013 |
| Artmossphere Ltd | Administrative & support | 2009 |
| Arty Marketing Limited | Administrative & support | 2004 |
| Arula Companies Ltd | Wholesale & retail | 2025 |
| Arush Limited | Wholesale & retail | 2025 |
| Ascenditclimbing Ltd | Wholesale & retail | 2025 |
| ASD UK Limited | Construction | 2009 |
| ASH & Co Workshops Ltd | Education | 2020 |
| ASH Digital Limited | Information & communication | 2014 |
| Ashco Management Limited | Manufacturing | 2013 |
| Ashdell Road Management Company Limited | Other services | 2006 |
| Ashneer Grocery Ltd | Wholesale & retail | 2026 |
| Ashneer Properties Ltd | Real estate | 2026 |
| Ashway Management Limited | Real estate | 1989 |
| ASI Plumbing and Heating Ltd | Construction | 2019 |
| Asjs Property Limited | Real estate | 2025 |
| ASK Mandy Ltd | Education | 2022 |
| Aspect Global Limited | Real estate | 2016 |
| Aspire (Farnborough) Management Company Limited | Households | 2006 |
| Aspire HR Ltd | Professional & scientific | 2008 |
| Assessment Success Ltd | Professional & scientific | 2014 |
| Assured Financial Group Ltd | Financial services | 2019 |
| Assured Fire Safety Consultancy Limited | Financial services | 2019 |
| Asteri Consultants Limited | Professional & scientific | 2024 |
| Asure Technology Ltd | Extraterritorial | 2018 |
| Aswad Stone Ltd | Wholesale & retail | 2023 |
| Atlantis Transport Services Limited | Transport & logistics | 2021 |
| Attlee Carpets Limited | Construction | 2025 |
| Auns Solutions Ltd | Professional & scientific | 2017 |
| Auth Energy Limited | Professional & scientific | 2018 |
| Authentic Change Solutions Limited | Professional & scientific | 2016 |
| Autocars Southern Limited | Wholesale & retail | 2011 |
| Autospin Limited | | 2007 |
| Autotelica Ltd | Information & communication | 2024 |
| Autumn Ltd | Professional & scientific | 2011 |
| AV Elite Installations Ltd | Manufacturing | 2012 |
| AVC Consultancy Ltd | Professional & scientific | 2024 |